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</style></head><body class="is-2-column"><nav class="navbar navbar-main"><div class="container navbar-container"><div class="navbar-brand justify-content-center"><a class="navbar-item navbar-logo" href="/"><img src="/img/logo.svg" alt="ForgotDream 的博客" height="28"></a></div><div class="navbar-menu"><div class="navbar-start"><a class="navbar-item is-active" href="/">Home</a><a class="navbar-item" href="/archives">Archives</a><a class="navbar-item" href="/categories">Categories</a><a class="navbar-item" href="/tags">Tags</a><a class="navbar-item" href="/about">About</a></div><div class="navbar-end"><a class="navbar-item" target="_blank" rel="noopener" title="Download on GitHub" href="https://github.com/ForgotDream/blog"><i class="fab fa-github"></i></a><a class="navbar-item search" title="搜索" href="javascript:;"><i class="fas fa-search"></i></a></div></div></div></nav><section class="section"><div class="container"><div class="columns"><div class="column order-2 column-main is-8-tablet is-8-desktop is-8-widescreen"><div class="card"><article class="card-content article" role="article"><div class="article-meta is-size-7 is-uppercase level is-mobile"><div class="level-left"><span class="level-item"><time dateTime="2024-01-29T00:23:05.000Z" title="2024/1/29 08:23:05">2024-01-29</time>发表</span><span class="level-item"><time dateTime="2024-01-29T01:28:11.357Z" title="2024/1/29 09:28:11">2024-01-29</time>更新</span><span class="level-item"><a class="link-muted" href="/categories/%E6%B8%B8%E8%AE%B0/">游记</a></span><span class="level-item">12 分钟读完 (大约1765个字)</span></div></div><p class="title is-3 is-size-4-mobile"><a class="link-muted" href="/2024/01/29/PKUWC-2024-%E6%B8%B8%E8%AE%B0/">PKUWC 2024 游记</a></p><div class="content"><p>省流:打的一坨屎。不过我本来就是去旅游的,感觉还比较平衡!</p>
<p>25 号上午 7:35 出发,坐动车前往重庆,不过中间在宜昌东站转了一次车,到重庆的时候已经是傍晚了。在动车上把《只有我不在的城市》看完了,感觉非常震撼,前边的节奏非常好,就是最后结局感觉还是有点仓促,是不是改成 24 集的话会好很多?总归还是感谢 ckain 的推荐!</p>
<p>订的酒店有点阴间,离育才有大概二十分钟的脚程。</p>
<p>晚上一个人打车前往洪崖洞,然后跟 ckain 与 kernel_panic 体验了下重庆的 “微微辣” 火锅,非常震撼!</p>
<p>然后就是 Day 1 了!</p>
<p>上午开幕式,云浅坐在我旁边!第一次见到本人啊,感觉非常帅。</p>
<p>然后育才本校的 DaydreamWarrior 同学坐在我的比较靠右的位置,遂跟他一起离场。</p>
<p>开幕式搞完了之后还有拍照的环节。发现粥群群友 AlphaDrawer 站在我旁边遂交换徽章并收到了签名!</p>
<p>然后试机,发现电脑配置非常厉害啊,不知道评测机咋样。</p>
<p>试机题据说多年没换过了,感觉没啥水平,因为既然我都会做,那这道题目的难度显然不会超过普及组 T3。</p>
<p>出来之后面到了 DitaMirika,老哥人真的很好啊!</p>
<p>中午还碰到了 irris 跟 nalemy,多亏有老哥带我随机游走啊/ll,准备午休的时候还看到了可爱的 yinhee/se/se/se。</p>
<p>然后就是非常厉害的比赛啊。T1 写了 3 个小时,最后喜提一百分了。</p>
<p>比较厉害的是我 T1 的规律是在猜了两个多小时之后花十分钟写了个暴力打表之后一眼看出来的,写完之后我一直在怀疑我前两个多小时都干了些啥。不过还好不是省选,这也算是个很好的教训了吧!T3 没看懂,然后发现读懂题意就有 40 分了。T2 是神秘的 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.566ex;" xmlns="http://www.w3.org/2000/svg" width="5.832ex" height="2.452ex" role="img" focusable="false" viewBox="0 -833.9 2577.6 1083.9"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="mi"><path data-c="1D442" d="M740 435Q740 320 676 213T511 42T304 -22Q207 -22 138 35T51 201Q50 209 50 244Q50 346 98 438T227 601Q351 704 476 704Q514 704 524 703Q621 689 680 617T740 435ZM637 476Q637 565 591 615T476 665Q396 665 322 605Q242 542 200 428T157 216Q157 126 200 73T314 19Q404 19 485 98T608 313Q637 408 637 476Z"></path></g><g data-mml-node="mo" transform="translate(763,0)"><path data-c="28" d="M94 250Q94 319 104 381T127 488T164 576T202 643T244 695T277 729T302 750H315H319Q333 750 333 741Q333 738 316 720T275 667T226 581T184 443T167 250T184 58T225 -81T274 -167T316 -220T333 -241Q333 -250 318 -250H315H302L274 -226Q180 -141 137 -14T94 250Z"></path></g><g data-mml-node="msup" transform="translate(1152,0)"><g data-mml-node="mi"><path data-c="1D45B" d="M21 287Q22 293 24 303T36 341T56 388T89 425T135 442Q171 442 195 424T225 390T231 369Q231 367 232 367L243 378Q304 442 382 442Q436 442 469 415T503 336T465 179T427 52Q427 26 444 26Q450 26 453 27Q482 32 505 65T540 145Q542 153 560 153Q580 153 580 145Q580 144 576 130Q568 101 554 73T508 17T439 -10Q392 -10 371 17T350 73Q350 92 386 193T423 345Q423 404 379 404H374Q288 404 229 303L222 291L189 157Q156 26 151 16Q138 -11 108 -11Q95 -11 87 -5T76 7T74 17Q74 30 112 180T152 343Q153 348 153 366Q153 405 129 405Q91 405 66 305Q60 285 60 284Q58 278 41 278H27Q21 284 21 287Z"></path></g><g data-mml-node="mn" transform="translate(633,363) scale(0.707)"><path data-c="35" d="M164 157Q164 133 148 117T109 101H102Q148 22 224 22Q294 22 326 82Q345 115 345 210Q345 313 318 349Q292 382 260 382H254Q176 382 136 314Q132 307 129 306T114 304Q97 304 95 310Q93 314 93 485V614Q93 664 98 664Q100 666 102 666Q103 666 123 658T178 642T253 634Q324 634 389 662Q397 666 402 666Q410 666 410 648V635Q328 538 205 538Q174 538 149 544L139 546V374Q158 388 169 396T205 412T256 420Q337 420 393 355T449 201Q449 109 385 44T229 -22Q148 -22 99 32T50 154Q50 178 61 192T84 210T107 214Q132 214 148 197T164 157Z"></path></g></g><g data-mml-node="mo" transform="translate(2188.6,0)"><path data-c="29" d="M60 749L64 750Q69 750 74 750H86L114 726Q208 641 251 514T294 250Q294 182 284 119T261 12T224 -76T186 -143T145 -194T113 -227T90 -246Q87 -249 86 -250H74Q66 -250 63 -250T58 -247T55 -238Q56 -237 66 -225Q221 -64 221 250T66 725Q56 737 55 738Q55 746 60 749Z"></path></g></g></g></svg></mjx-container> DP,感觉一股 atc 味,不过 11 分的暴力都没写,非常失败,主要是赛时一直在想高斯消元有关的做法,结果 1) 忘了板子怎么写了; 2) 这个做法本来就是假的,因为有很多自由元,根本算不了一点。</p>
<p>晚上聚餐!由于 Day 0 晚上是我去的 kernel_panic 那边,所以这天晚上换他们来我这边!顺便还邀请到了 DitaMirika 一起来!</p>
<p>在万象城里随机游走,结果一直都没怎么找到吃饭的地方,最后选了一家烤肉店点了个四人套餐,感觉吃得还是挺饱的。这天晚上没有出钱,钱是 DitaMirika 的妈妈出的,唉太感谢了。</p>
<p>然后老哥貌似对湖北人都挺熟的,尤其是 hsy 那边的,感觉他比我们三个正经湖北人都熟啊!且还听到了 “我感觉上 IGM 不难” 的这种批话,狠狠膜拜了。zyz master when/ll,怨念啊,都是怨念。</p>
<p>晚上加训战地 5,然后发生了非常不好的事情:手机屏幕摔坏了。摔了之后还没啥感觉,只是有一部分断触点,结果第二天早上一看我草整个屏幕都黑了,根本用不了,直接要了我的半条老命。</p>
<p>Day 2 上午是讲座,P 这边的是有关编程语言的啊!感觉非常的有趣,我还是第一次知道 逻辑式编程 这个概念,后边的 代码标注 啥的感觉也挺有意思的。PPT 上的演示语言貌似是 Haskell,结束之后稍微看了下 Real World Haskell,感觉非常有意思!</p>
<p>中午因为没手机,所以就一直粘着 DitaMirika,真是麻烦老哥了/wq。</p>
<p>下午比赛。T1 一开始一直在写神秘随机化,结果发现如果写的好的话只有最后一个包过不了!遂调参怒交 21 发。但最后随便写了个贪心居然过了?就是从和为 5 的一直贪到和为 9 的,然后随便写写就对了?然后开 T2,想了很久感觉一点思路都没有,于是把 18pts 的暴力写了,然后找规律写了个 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.186ex;" xmlns="http://www.w3.org/2000/svg" width="6.135ex" height="1.692ex" role="img" focusable="false" viewBox="0 -666 2711.6 748"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="mi"><path data-c="1D45A" d="M21 287Q22 293 24 303T36 341T56 388T88 425T132 442T175 435T205 417T221 395T229 376L231 369Q231 367 232 367L243 378Q303 442 384 442Q401 442 415 440T441 433T460 423T475 411T485 398T493 385T497 373T500 364T502 357L510 367Q573 442 659 442Q713 442 746 415T780 336Q780 285 742 178T704 50Q705 36 709 31T724 26Q752 26 776 56T815 138Q818 149 821 151T837 153Q857 153 857 145Q857 144 853 130Q845 101 831 73T785 17T716 -10Q669 -10 648 17T627 73Q627 92 663 193T700 345Q700 404 656 404H651Q565 404 506 303L499 291L466 157Q433 26 428 16Q415 -11 385 -11Q372 -11 364 -4T353 8T350 18Q350 29 384 161L420 307Q423 322 423 345Q423 404 379 404H374Q288 404 229 303L222 291L189 157Q156 26 151 16Q138 -11 108 -11Q95 -11 87 -5T76 7T74 17Q74 30 112 181Q151 335 151 342Q154 357 154 369Q154 405 129 405Q107 405 92 377T69 316T57 280Q55 278 41 278H27Q21 284 21 287Z"></path></g><g data-mml-node="mo" transform="translate(1155.8,0)"><path data-c="3D" d="M56 347Q56 360 70 367H707Q722 359 722 347Q722 336 708 328L390 327H72Q56 332 56 347ZM56 153Q56 168 72 173H708Q722 163 722 153Q722 140 707 133H70Q56 140 56 153Z"></path></g><g data-mml-node="mn" transform="translate(2211.6,0)"><path data-c="32" d="M109 429Q82 429 66 447T50 491Q50 562 103 614T235 666Q326 666 387 610T449 465Q449 422 429 383T381 315T301 241Q265 210 201 149L142 93L218 92Q375 92 385 97Q392 99 409 186V189H449V186Q448 183 436 95T421 3V0H50V19V31Q50 38 56 46T86 81Q115 113 136 137Q145 147 170 174T204 211T233 244T261 278T284 308T305 340T320 369T333 401T340 431T343 464Q343 527 309 573T212 619Q179 619 154 602T119 569T109 550Q109 549 114 549Q132 549 151 535T170 489Q170 464 154 447T109 429Z"></path></g></g></g></svg></mjx-container> 的包,一共有 28pts,据说是大众分。开始 T3 的时候只剩一个小时了,由于我是 STL 苦手所以我最低档暴力就写了 30min,结果 15pts 的板子 Segment Tree Beats 没写完就结束了。</p>
<p><img src="https://www.z4a.net/images/2024/01/29/2024-01-29_09-05.png" alt="2024-01-29_09-05.png"></p>
<p>感觉总结下来,两天的比赛主要还是策略问题,尤其是第一天,我自认为按我的水平冲到大众分 151 是没有任何问题的,但是 T1 的策略失误直接导致时间上的大失败,最后暴力都没拼完。第二天相对比较正常,但是还是在 T2 上分配了过多的时间,导致 T3 15pts 没写完。</p>
<p>如果发挥正常的话是不是能上 300 啊?天知道啊,马后炮没有任何意义啊!只能说幸好不是省选,不然真就抱憾终生了。</p>
<p>晚上聚餐啊!一共十二个人,他们分别是:</p>
<p><img src="https://www.z4a.net/images/2024/01/29/2024-01-29_09-13.png" alt="2024-01-29_09-13.png"></p>
<p>因为没手机,所以只好一直粘着 DaydreamWarrior,好人一生平安/ll。</p>
<p>晚上正好碰到了粥的冬日前瞻直播,结果直接变成粥批同好会了,感觉跟他们交流会暴露我云玩的本质,根本插不进嘴。于是我们这桌就提前离场了。</p>
<p>晚上接着加训战地 5。感觉酒店网络的 ping 虽然高点,但是 loss 比较正常,玩起来还是可以接受的。</p>
<p>第二天早起回家了,还是动车,不过这次没有转车。在车上把《昨日之歌》看完了,据说原作是从 99 年连载到 15 年的漫画,感觉很厉害啊!不过感觉最后陆生跟小晴那一段还是有点仓促,而且陆生跟榀子看得确实,额,非常的折磨,不过总体上还是蛮厉害的感觉。到家的时候已经四点了。</p>
<p>徽章还有一堆没换,不过我没有 WC,估计是换不出去了。</p>
<p>徽章的照片等我回家再说。</p>
</div></article></div><div class="card"><article class="card-content article" role="article"><div class="article-meta is-size-7 is-uppercase level is-mobile"><div class="level-left"><span class="level-item"><time dateTime="2024-01-22T06:59:46.000Z" title="2024/1/22 14:59:46">2024-01-22</time>发表</span><span class="level-item"><time dateTime="2024-01-22T07:11:47.880Z" title="2024/1/22 15:11:47">2024-01-22</time>更新</span><span class="level-item"><a class="link-muted" href="/categories/%E9%A2%98%E8%A7%A3/">题解</a><span> / </span><a class="link-muted" href="/categories/%E9%A2%98%E8%A7%A3/Luogu/">Luogu</a></span><span class="level-item">3 分钟读完 (大约514个字)</span></div></div><p class="title is-3 is-size-4-mobile"><a class="link-muted" href="/2024/01/22/P2414-NOI2011-%E9%98%BF%E7%8B%B8%E7%9A%84%E6%89%93%E5%AD%97%E6%9C%BA/">P2414 [NOI2011] 阿狸的打字机</a></p><div class="content"><p>题意类似多模式串匹配,因此我们考虑建出 AC 自动机,然后离线下来,将询问挂到文本串对应的 AC 自动机的节点上。</p>
<p>然后就很好做了,我们考虑对 fail 树进行 DFS,容易得到模式串被文本串匹配的次数就是文本串对应的节点位于模式串末尾节点子树内部的个数,这个我们直接用 BIT 处理即可。</p>
<figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br><span class="line">68</span><br><span class="line">69</span><br><span class="line">70</span><br><span class="line">71</span><br><span class="line">72</span><br><span class="line">73</span><br><span class="line">74</span><br><span class="line">75</span><br><span class="line">76</span><br><span class="line">77</span><br><span class="line">78</span><br><span class="line">79</span><br><span class="line">80</span><br><span class="line">81</span><br><span class="line">82</span><br><span class="line">83</span><br><span class="line">84</span><br><span class="line">85</span><br><span class="line">86</span><br><span class="line">87</span><br><span class="line">88</span><br><span class="line">89</span><br><span class="line">90</span><br><span class="line">91</span><br><span class="line">92</span><br><span class="line">93</span><br><span class="line">94</span><br><span class="line">95</span><br><span class="line">96</span><br><span class="line">97</span><br><span class="line">98</span><br><span class="line">99</span><br><span class="line">100</span><br><span class="line">101</span><br><span class="line">102</span><br><span class="line">103</span><br><span class="line">104</span><br><span class="line">105</span><br><span class="line">106</span><br><span class="line">107</span><br><span class="line">108</span><br><span class="line">109</span><br><span class="line">110</span><br><span class="line">111</span><br><span class="line">112</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string"><bits/stdc++.h></span></span></span><br><span class="line"></span><br><span class="line"><span class="keyword">using</span> i64 = <span class="type">long</span> <span class="type">long</span>;</span><br><span class="line"><span class="keyword">using</span> pii = std::pair<<span class="type">int</span>, <span class="type">int</span>>;</span><br><span class="line"></span><br><span class="line"><span class="keyword">constexpr</span> <span class="type">int</span> N = <span class="number">2e5</span> + <span class="number">50</span>;</span><br><span class="line"></span><br><span class="line">std::string s;</span><br><span class="line"><span class="type">int</span> m;</span><br><span class="line">std::vector<pii> qry[N];</span><br><span class="line"></span><br><span class="line"><span class="keyword">struct</span> <span class="title class_">ACAM</span> {</span><br><span class="line"> <span class="type">int</span> ch[N][<span class="number">26</span>], nxt[N], cnt, fa[N], end[N], to[N];</span><br><span class="line"> <span class="type">int</span> tr[N][<span class="number">26</span>];</span><br><span class="line"> <span class="function"><span class="type">void</span> <span class="title">eval</span><span class="params">(<span class="type">const</span> std::string_view &s)</span> </span>{</span><br><span class="line"> <span class="type">int</span> p = <span class="number">0</span>, sc = <span class="number">0</span>;</span><br><span class="line"> <span class="keyword">for</span> (<span class="keyword">auto</span> c : s) {</span><br><span class="line"> <span class="keyword">if</span> (c == <span class="string">'B'</span>) {</span><br><span class="line"> p = fa[p];</span><br><span class="line"> } <span class="keyword">else</span> <span class="keyword">if</span> (c == <span class="string">'P'</span>) {</span><br><span class="line"> end[p] = ++sc, to[sc] = p;</span><br><span class="line"> } <span class="keyword">else</span> {</span><br><span class="line"> <span class="keyword">if</span> (!ch[p][c - <span class="string">'a'</span>]) ch[p][c - <span class="string">'a'</span>] = ++cnt;</span><br><span class="line"> fa[ch[p][c - <span class="string">'a'</span>]] = p, p = ch[p][c - <span class="string">'a'</span>];</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> <span class="function"><span class="type">void</span> <span class="title">build</span><span class="params">()</span> </span>{</span><br><span class="line"> std::queue<<span class="type">int</span>> q;</span><br><span class="line"> <span class="keyword">for</span> (<span class="type">int</span> i = <span class="number">0</span>; i < <span class="number">26</span>; i++) {</span><br><span class="line"> <span class="keyword">if</span> (ch[<span class="number">0</span>][i]) q.<span class="built_in">push</span>(ch[<span class="number">0</span>][i]);</span><br><span class="line"> tr[<span class="number">0</span>][i] = ch[<span class="number">0</span>][i];</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">while</span> (!q.<span class="built_in">empty</span>()) {</span><br><span class="line"> <span class="type">int</span> u = q.<span class="built_in">front</span>();</span><br><span class="line"> q.<span class="built_in">pop</span>();</span><br><span class="line"> <span class="keyword">for</span> (<span class="type">int</span> i = <span class="number">0</span>; i < <span class="number">26</span>; i++) {</span><br><span class="line"> <span class="type">int</span> &v = ch[u][i];</span><br><span class="line"> tr[u][i] = v;</span><br><span class="line"> <span class="keyword">if</span> (!v) v = ch[nxt[u]][i];</span><br><span class="line"> <span class="keyword">else</span> nxt[v] = ch[nxt[u]][i], q.<span class="built_in">push</span>(v);</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line">} ac;</span><br><span class="line"></span><br><span class="line"><span class="type">int</span> dfn[N], siz[N], clk;</span><br><span class="line">std::vector<<span class="type">int</span>> adj[N];</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="type">int</span> <span class="title">in</span><span class="params">(<span class="type">int</span> u)</span> </span>{ <span class="keyword">return</span> dfn[u]; }</span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="type">int</span> <span class="title">out</span><span class="params">(<span class="type">int</span> u)</span> </span>{ <span class="keyword">return</span> dfn[u] + siz[u] - <span class="number">1</span>; }</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">dfs</span><span class="params">(<span class="type">int</span> u)</span> </span>{</span><br><span class="line"> dfn[u] = ++clk, siz[u] = <span class="number">1</span>;</span><br><span class="line"> <span class="keyword">for</span> (<span class="keyword">auto</span> v : adj[u]) <span class="built_in">dfs</span>(v), siz[u] += siz[v];</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"><span class="keyword">struct</span> <span class="title class_">BIT</span> {</span><br><span class="line"> <span class="type">int</span> tree[N];</span><br><span class="line"> <span class="function"><span class="type">void</span> <span class="title">modify</span><span class="params">(<span class="type">int</span> u, <span class="type">int</span> val)</span> </span>{</span><br><span class="line"> <span class="keyword">for</span> (<span class="type">int</span> i = u; i <= clk; i += i & -i) tree[i] += val;</span><br><span class="line"> }</span><br><span class="line"> <span class="function"><span class="type">int</span> <span class="title">query</span><span class="params">(<span class="type">int</span> u)</span> </span>{</span><br><span class="line"> <span class="type">int</span> res = <span class="number">0</span>;</span><br><span class="line"> <span class="keyword">for</span> (<span class="type">int</span> i = u; i; i -= i & -i) res += tree[i];</span><br><span class="line"> <span class="keyword">return</span> res;</span><br><span class="line"> }</span><br><span class="line"> <span class="function"><span class="type">int</span> <span class="title">query</span><span class="params">(<span class="type">int</span> l, <span class="type">int</span> r)</span> </span>{ <span class="keyword">return</span> <span class="built_in">query</span>(r) - <span class="built_in">query</span>(l - <span class="number">1</span>); }</span><br><span class="line">} bit;</span><br><span class="line"></span><br><span class="line"><span class="type">int</span> ans[N];</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">calc</span><span class="params">(<span class="type">int</span> u)</span> </span>{</span><br><span class="line"> bit.<span class="built_in">modify</span>(dfn[u], <span class="number">1</span>);</span><br><span class="line"> <span class="keyword">if</span> (ac.end[u]) {</span><br><span class="line"> <span class="keyword">for</span> (<span class="keyword">auto</span> [x, i] : qry[ac.end[u]]) {</span><br><span class="line"> ans[i] = bit.<span class="built_in">query</span>(<span class="built_in">in</span>(ac.to[x]), <span class="built_in">out</span>(ac.to[x]));</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">for</span> (<span class="type">int</span> i = <span class="number">0</span>; i < <span class="number">26</span>; i++) {</span><br><span class="line"> <span class="keyword">if</span> (!ac.tr[u][i]) <span class="keyword">continue</span>;</span><br><span class="line"> <span class="built_in">calc</span>(ac.tr[u][i]);</span><br><span class="line"> }</span><br><span class="line"> bit.<span class="built_in">modify</span>(dfn[u], <span class="number">-1</span>);</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">solve</span><span class="params">()</span> </span>{</span><br><span class="line"> std::cin >> s;</span><br><span class="line"> ac.<span class="built_in">eval</span>(s), ac.<span class="built_in">build</span>();</span><br><span class="line"></span><br><span class="line"> <span class="keyword">for</span> (<span class="type">int</span> i = <span class="number">1</span>; i <= ac.cnt; i++) adj[ac.nxt[i]].<span class="built_in">push_back</span>(i);</span><br><span class="line"> <span class="built_in">dfs</span>(<span class="number">0</span>);</span><br><span class="line"></span><br><span class="line"> std::cin >> m;</span><br><span class="line"> <span class="keyword">for</span> (<span class="type">int</span> i = <span class="number">1</span>, x, y; i <= m; i++) {</span><br><span class="line"> std::cin >> x >> y;</span><br><span class="line"> qry[y].<span class="built_in">emplace_back</span>(x, i);</span><br><span class="line"> }</span><br><span class="line"></span><br><span class="line"> <span class="built_in">calc</span>(<span class="number">0</span>);</span><br><span class="line"> <span class="keyword">for</span> (<span class="type">int</span> i = <span class="number">1</span>; i <= m; i++) std::cout << ans[i] << <span class="string">"\n"</span>;</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">signed</span> <span class="title">main</span><span class="params">()</span> </span>{</span><br><span class="line"> std::cin.<span class="built_in">tie</span>(<span class="literal">nullptr</span>)-><span class="built_in">sync_with_stdio</span>(<span class="literal">false</span>);</span><br><span class="line"></span><br><span class="line"> <span class="type">int</span> t = <span class="number">1</span>;</span><br><span class="line"> <span class="comment">// std::cin >> t;</span></span><br><span class="line"> <span class="keyword">while</span> (t--) <span class="built_in">solve</span>();</span><br><span class="line"></span><br><span class="line"> <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">}</span><br></pre></td></tr></table></figure>
</div></article></div><div class="card"><article class="card-content article" role="article"><div class="article-meta is-size-7 is-uppercase level is-mobile"><div class="level-left"><span class="level-item"><time dateTime="2024-01-22T06:48:59.000Z" title="2024/1/22 14:48:59">2024-01-22</time>发表</span><span class="level-item"><time dateTime="2024-01-22T07:00:32.326Z" title="2024/1/22 15:00:32">2024-01-22</time>更新</span><span class="level-item"><a class="link-muted" href="/categories/%E9%A2%98%E8%A7%A3/">题解</a><span> / </span><a class="link-muted" href="/categories/%E9%A2%98%E8%A7%A3/Luogu/">Luogu</a></span><span class="level-item">3 分钟读完 (大约519个字)</span></div></div><p class="title is-3 is-size-4-mobile"><a class="link-muted" href="/2024/01/22/P3346-ZJOI2015-%E8%AF%B8%E7%A5%9E%E7%9C%B7%E9%A1%BE%E7%9A%84%E5%B9%BB%E6%83%B3%E4%B9%A1/">P3346 [ZJOI2015] 诸神眷顾的幻想乡</a></p><div class="content"><p>这东西天然构成一棵字典树,考虑建出广义 SAM 来做。</p>
<p>但是发现如果钦定某一个节点为根的话,则只能统计出从这个节点出发的所有串,并不能包含所有的串。但是我们注意到题目保证叶子数不超过 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.05ex;" xmlns="http://www.w3.org/2000/svg" width="2.262ex" height="1.557ex" role="img" focusable="false" viewBox="0 -666 1000 688"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="mn"><path data-c="32" d="M109 429Q82 429 66 447T50 491Q50 562 103 614T235 666Q326 666 387 610T449 465Q449 422 429 383T381 315T301 241Q265 210 201 149L142 93L218 92Q375 92 385 97Q392 99 409 186V189H449V186Q448 183 436 95T421 3V0H50V19V31Q50 38 56 46T86 81Q115 113 136 137Q145 147 170 174T204 211T233 244T261 278T284 308T305 340T320 369T333 401T340 431T343 464Q343 527 309 573T212 619Q179 619 154 602T119 569T109 550Q109 549 114 549Q132 549 151 535T170 489Q170 464 154 447T109 429Z"></path><path data-c="30" d="M96 585Q152 666 249 666Q297 666 345 640T423 548Q460 465 460 320Q460 165 417 83Q397 41 362 16T301 -15T250 -22Q224 -22 198 -16T137 16T82 83Q39 165 39 320Q39 494 96 585ZM321 597Q291 629 250 629Q208 629 178 597Q153 571 145 525T137 333Q137 175 145 125T181 46Q209 16 250 16Q290 16 318 46Q347 76 354 130T362 333Q362 478 354 524T321 597Z" transform="translate(500,0)"></path></g></g></g></svg></mjx-container> 个,因此我们可以依次枚举每一个叶子节点作为字典树的根,然后将从这个节点出发的点全部都塞到广义 SAM 里边去,容易发现这样搞虽然可能会重,但一定不会漏,而我们求的是本质不同子串的数量,因此重复的串并不影响答案。</p>
<figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br><span class="line">68</span><br><span class="line">69</span><br><span class="line">70</span><br><span class="line">71</span><br><span class="line">72</span><br><span class="line">73</span><br><span class="line">74</span><br><span class="line">75</span><br><span class="line">76</span><br><span class="line">77</span><br><span class="line">78</span><br><span class="line">79</span><br><span class="line">80</span><br><span class="line">81</span><br><span class="line">82</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string"><bits/stdc++.h></span></span></span><br><span class="line"></span><br><span class="line"><span class="keyword">using</span> i64 = <span class="type">long</span> <span class="type">long</span>;</span><br><span class="line"></span><br><span class="line"><span class="comment">// 增量构造吧,直接拉出来不是很好写</span></span><br><span class="line"></span><br><span class="line"><span class="keyword">constexpr</span> <span class="type">int</span> N = <span class="number">4e6</span> + <span class="number">50</span>;</span><br><span class="line"></span><br><span class="line"><span class="type">int</span> n, c, a[N];</span><br><span class="line">std::vector<<span class="type">int</span>> adj[N];</span><br><span class="line"><span class="type">int</span> deg[N];</span><br><span class="line"></span><br><span class="line"><span class="keyword">struct</span> <span class="title class_">GSAM</span> {</span><br><span class="line"> <span class="type">int</span> ch[N][<span class="number">10</span>], link[N], len[N], cnt = <span class="number">1</span>;</span><br><span class="line"> <span class="function"><span class="type">int</span> <span class="title">expand</span><span class="params">(<span class="type">int</span> lst, <span class="type">int</span> d)</span> </span>{</span><br><span class="line"> <span class="type">int</span> cur = ch[lst][d];</span><br><span class="line"> <span class="keyword">if</span> (len[cur]) <span class="keyword">return</span> cur;</span><br><span class="line"> len[cur] = len[lst] + <span class="number">1</span>;</span><br><span class="line"> <span class="type">int</span> p = link[lst];</span><br><span class="line"> <span class="keyword">for</span> (; p && !ch[p][d]; p = link[p]) ch[p][d] = cur;</span><br><span class="line"> <span class="keyword">if</span> (!p) {</span><br><span class="line"> link[cur] = <span class="number">1</span>;</span><br><span class="line"> } <span class="keyword">else</span> {</span><br><span class="line"> <span class="type">int</span> q = ch[p][d];</span><br><span class="line"> <span class="keyword">if</span> (len[p] + <span class="number">1</span> == len[q]) {</span><br><span class="line"> link[cur] = q;</span><br><span class="line"> } <span class="keyword">else</span> {</span><br><span class="line"> <span class="type">int</span> tmp = ++cnt;</span><br><span class="line"> len[tmp] = len[p] + <span class="number">1</span>, link[tmp] = link[q];</span><br><span class="line"> <span class="keyword">for</span> (<span class="type">int</span> i = <span class="number">0</span>; i < c; i++) ch[tmp][i] = len[ch[q][i]] ? ch[q][i] : <span class="number">0</span>;</span><br><span class="line"> <span class="keyword">for</span> (; p && ch[p][d] == q; p = link[p]) ch[p][d] = tmp;</span><br><span class="line"> link[cur] = link[q] = tmp;</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">return</span> cur;</span><br><span class="line"> }</span><br><span class="line"> <span class="function"><span class="type">void</span> <span class="title">build</span><span class="params">()</span> </span>{</span><br><span class="line"> std::queue<std::pair<<span class="type">int</span>, <span class="type">int</span>>> q;</span><br><span class="line"> <span class="keyword">for</span> (<span class="type">int</span> i = <span class="number">0</span>; i < c; i++) <span class="keyword">if</span> (ch[<span class="number">1</span>][i]) q.<span class="built_in">emplace</span>(<span class="number">1</span>, i);</span><br><span class="line"> <span class="keyword">while</span> (!q.<span class="built_in">empty</span>()) {</span><br><span class="line"> <span class="keyword">auto</span> [u, d] = q.<span class="built_in">front</span>();</span><br><span class="line"> q.<span class="built_in">pop</span>(), u = <span class="built_in">expand</span>(u, d);</span><br><span class="line"> <span class="keyword">for</span> (<span class="type">int</span> i = <span class="number">0</span>; i < c; i++) <span class="keyword">if</span> (ch[u][i]) q.<span class="built_in">emplace</span>(u, i);</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line">} gsam;</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">dfs</span><span class="params">(<span class="type">int</span> u, <span class="type">int</span> frm, <span class="type">int</span> p)</span> </span>{</span><br><span class="line"> <span class="keyword">if</span> (!gsam.ch[p][a[u]]) gsam.ch[p][a[u]] = ++gsam.cnt;</span><br><span class="line"> p = gsam.ch[p][a[u]];</span><br><span class="line"> <span class="keyword">for</span> (<span class="keyword">auto</span> v : adj[u]) {</span><br><span class="line"> <span class="keyword">if</span> (v == frm) <span class="keyword">continue</span>;</span><br><span class="line"> <span class="built_in">dfs</span>(v, u, p);</span><br><span class="line"> }</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">solve</span><span class="params">()</span> </span>{</span><br><span class="line"> std::cin >> n >> c;</span><br><span class="line"> <span class="keyword">for</span> (<span class="type">int</span> i = <span class="number">1</span>; i <= n; i++) std::cin >> a[i];</span><br><span class="line"> <span class="keyword">for</span> (<span class="type">int</span> i = <span class="number">1</span>, u, v; i < n; i++) {</span><br><span class="line"> std::cin >> u >> v;</span><br><span class="line"> adj[u].<span class="built_in">push_back</span>(v), adj[v].<span class="built_in">push_back</span>(u);</span><br><span class="line"> deg[u]++, deg[v]++;</span><br><span class="line"> }</span><br><span class="line"></span><br><span class="line"> <span class="keyword">for</span> (<span class="type">int</span> i = <span class="number">1</span>; i <= n; i++) <span class="keyword">if</span> (deg[i] == <span class="number">1</span>) <span class="built_in">dfs</span>(i, <span class="number">0</span>, <span class="number">1</span>);</span><br><span class="line"> gsam.<span class="built_in">build</span>();</span><br><span class="line"></span><br><span class="line"> i64 ans = <span class="number">0</span>;</span><br><span class="line"> <span class="keyword">for</span> (<span class="type">int</span> i = <span class="number">1</span>; i <= gsam.cnt; i++) ans += gsam.len[i] - gsam.len[gsam.link[i]];</span><br><span class="line"> std::cout << ans << <span class="string">"\n"</span>;</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">signed</span> <span class="title">main</span><span class="params">()</span> </span>{</span><br><span class="line"> std::cin.<span class="built_in">tie</span>(<span class="literal">nullptr</span>)-><span class="built_in">sync_with_stdio</span>(<span class="literal">false</span>);</span><br><span class="line"></span><br><span class="line"> <span class="type">int</span> t = <span class="number">1</span>;</span><br><span class="line"> <span class="comment">// std::cin >> t;</span></span><br><span class="line"> <span class="keyword">while</span> (t--) <span class="built_in">solve</span>();</span><br><span class="line"></span><br><span class="line"> <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">}</span><br></pre></td></tr></table></figure>
</div></article></div><div class="card"><article class="card-content article" role="article"><div class="article-meta is-size-7 is-uppercase level is-mobile"><div class="level-left"><span class="level-item"><time dateTime="2024-01-22T06:26:19.000Z" title="2024/1/22 14:26:19">2024-01-22</time>发表</span><span class="level-item"><time dateTime="2024-01-22T07:00:19.946Z" title="2024/1/22 15:00:19">2024-01-22</time>更新</span><span class="level-item"><a class="link-muted" href="/categories/%E9%A2%98%E8%A7%A3/">题解</a><span> / </span><a class="link-muted" href="/categories/%E9%A2%98%E8%A7%A3/Luogu/">Luogu</a></span><span class="level-item">5 分钟读完 (大约729个字)</span></div></div><p class="title is-3 is-size-4-mobile"><a class="link-muted" href="/2024/01/22/P2178-NOI2015-%E5%93%81%E9%85%92%E5%A4%A7%E4%BC%9A/">P2178 [NOI2015] 品酒大会</a></p><div class="content"><p>首先容易得知两个 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.025ex;" xmlns="http://www.w3.org/2000/svg" width="1.02ex" height="1.025ex" role="img" focusable="false" viewBox="0 -442 451 453"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="mi"><path data-c="1D45F" d="M21 287Q22 290 23 295T28 317T38 348T53 381T73 411T99 433T132 442Q161 442 183 430T214 408T225 388Q227 382 228 382T236 389Q284 441 347 441H350Q398 441 422 400Q430 381 430 363Q430 333 417 315T391 292T366 288Q346 288 334 299T322 328Q322 376 378 392Q356 405 342 405Q286 405 239 331Q229 315 224 298T190 165Q156 25 151 16Q138 -11 108 -11Q95 -11 87 -5T76 7T74 17Q74 30 114 189T154 366Q154 405 128 405Q107 405 92 377T68 316T57 280Q55 278 41 278H27Q21 284 21 287Z"></path></g></g></g></svg></mjx-container> 相似的子串一定是 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.186ex;" xmlns="http://www.w3.org/2000/svg" width="4.917ex" height="1.692ex" role="img" focusable="false" viewBox="0 -666 2173.4 748"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="mi"><path data-c="1D45F" d="M21 287Q22 290 23 295T28 317T38 348T53 381T73 411T99 433T132 442Q161 442 183 430T214 408T225 388Q227 382 228 382T236 389Q284 441 347 441H350Q398 441 422 400Q430 381 430 363Q430 333 417 315T391 292T366 288Q346 288 334 299T322 328Q322 376 378 392Q356 405 342 405Q286 405 239 331Q229 315 224 298T190 165Q156 25 151 16Q138 -11 108 -11Q95 -11 87 -5T76 7T74 17Q74 30 114 189T154 366Q154 405 128 405Q107 405 92 377T68 316T57 280Q55 278 41 278H27Q21 284 21 287Z"></path></g><g data-mml-node="mo" transform="translate(673.2,0)"><path data-c="2212" d="M84 237T84 250T98 270H679Q694 262 694 250T679 230H98Q84 237 84 250Z"></path></g><g data-mml-node="mn" transform="translate(1673.4,0)"><path data-c="31" d="M213 578L200 573Q186 568 160 563T102 556H83V602H102Q149 604 189 617T245 641T273 663Q275 666 285 666Q294 666 302 660V361L303 61Q310 54 315 52T339 48T401 46H427V0H416Q395 3 257 3Q121 3 100 0H88V46H114Q136 46 152 46T177 47T193 50T201 52T207 57T213 61V578Z"></path></g></g></g></svg></mjx-container> 相似的,这是一个类似后缀包含的结构,我们可以很自然的联想到 SAM。</p>
<p>由于是后缀,因此我们考虑对反串建出 SAM,则容易知道两个后缀的最大相似度即为其对应节点在 link 树上的 LCA 的 <code>len</code>,也即是 LCP 的长度,根据经典套路我们可以考虑枚举 link 树上的每一个节点作为 LCA 来计算贡献。容易知道两个后缀的 LCP 对应节点为 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.025ex;" xmlns="http://www.w3.org/2000/svg" width="1.294ex" height="1.025ex" role="img" focusable="false" viewBox="0 -442 572 453"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="mi"><path data-c="1D462" d="M21 287Q21 295 30 318T55 370T99 420T158 442Q204 442 227 417T250 358Q250 340 216 246T182 105Q182 62 196 45T238 27T291 44T328 78L339 95Q341 99 377 247Q407 367 413 387T427 416Q444 431 463 431Q480 431 488 421T496 402L420 84Q419 79 419 68Q419 43 426 35T447 26Q469 29 482 57T512 145Q514 153 532 153Q551 153 551 144Q550 139 549 130T540 98T523 55T498 17T462 -8Q454 -10 438 -10Q372 -10 347 46Q345 45 336 36T318 21T296 6T267 -6T233 -11Q189 -11 155 7Q103 38 103 113Q103 170 138 262T173 379Q173 380 173 381Q173 390 173 393T169 400T158 404H154Q131 404 112 385T82 344T65 302T57 280Q55 278 41 278H27Q21 284 21 287Z"></path></g></g></g></svg></mjx-container> 时,后缀所对应的两个节点一定是分别位于 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.025ex;" xmlns="http://www.w3.org/2000/svg" width="1.294ex" height="1.025ex" role="img" focusable="false" viewBox="0 -442 572 453"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="mi"><path data-c="1D462" d="M21 287Q21 295 30 318T55 370T99 420T158 442Q204 442 227 417T250 358Q250 340 216 246T182 105Q182 62 196 45T238 27T291 44T328 78L339 95Q341 99 377 247Q407 367 413 387T427 416Q444 431 463 431Q480 431 488 421T496 402L420 84Q419 79 419 68Q419 43 426 35T447 26Q469 29 482 57T512 145Q514 153 532 153Q551 153 551 144Q550 139 549 130T540 98T523 55T498 17T462 -8Q454 -10 438 -10Q372 -10 347 46Q345 45 336 36T318 21T296 6T267 -6T233 -11Q189 -11 155 7Q103 38 103 113Q103 170 138 262T173 379Q173 380 173 381Q173 390 173 393T169 400T158 404H154Q131 404 112 385T82 344T65 302T57 280Q55 278 41 278H27Q21 284 21 287Z"></path></g></g></g></svg></mjx-container> 的不同子树内部的,因此很容易就能求出最大相似度为某一定值的后缀对数,又根据我们一开始得到的结论,我们只需要做一个后缀和就能得到相似度可以为某一个值的后缀对数。</p>
<p>再来考虑如何求最大值,根据上边的思路,我们只需要维护一棵子树内 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.357ex;" xmlns="http://www.w3.org/2000/svg" width="1.937ex" height="1.355ex" role="img" focusable="false" viewBox="0 -441 856 598.8"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="msub"><g data-mml-node="mi"><path data-c="1D44E" d="M33 157Q33 258 109 349T280 441Q331 441 370 392Q386 422 416 422Q429 422 439 414T449 394Q449 381 412 234T374 68Q374 43 381 35T402 26Q411 27 422 35Q443 55 463 131Q469 151 473 152Q475 153 483 153H487Q506 153 506 144Q506 138 501 117T481 63T449 13Q436 0 417 -8Q409 -10 393 -10Q359 -10 336 5T306 36L300 51Q299 52 296 50Q294 48 292 46Q233 -10 172 -10Q117 -10 75 30T33 157ZM351 328Q351 334 346 350T323 385T277 405Q242 405 210 374T160 293Q131 214 119 129Q119 126 119 118T118 106Q118 61 136 44T179 26Q217 26 254 59T298 110Q300 114 325 217T351 328Z"></path></g><g data-mml-node="mi" transform="translate(562,-150) scale(0.707)"><path data-c="1D456" d="M184 600Q184 624 203 642T247 661Q265 661 277 649T290 619Q290 596 270 577T226 557Q211 557 198 567T184 600ZM21 287Q21 295 30 318T54 369T98 420T158 442Q197 442 223 419T250 357Q250 340 236 301T196 196T154 83Q149 61 149 51Q149 26 166 26Q175 26 185 29T208 43T235 78T260 137Q263 149 265 151T282 153Q302 153 302 143Q302 135 293 112T268 61T223 11T161 -11Q129 -11 102 10T74 74Q74 91 79 106T122 220Q160 321 166 341T173 380Q173 404 156 404H154Q124 404 99 371T61 287Q60 286 59 284T58 281T56 279T53 278T49 278T41 278H27Q21 284 21 287Z"></path></g></g></g></g></svg></mjx-container> 的最大值、次大值、最小值、次小值即可求出答案,最后再做一个后缀 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.025ex;" xmlns="http://www.w3.org/2000/svg" width="4.21ex" height="1.038ex" role="img" focusable="false" viewBox="0 -448 1861 459"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="mo"><path data-c="6D" d="M41 46H55Q94 46 102 60V68Q102 77 102 91T102 122T103 161T103 203Q103 234 103 269T102 328V351Q99 370 88 376T43 385H25V408Q25 431 27 431L37 432Q47 433 65 434T102 436Q119 437 138 438T167 441T178 442H181V402Q181 364 182 364T187 369T199 384T218 402T247 421T285 437Q305 442 336 442Q351 442 364 440T387 434T406 426T421 417T432 406T441 395T448 384T452 374T455 366L457 361L460 365Q463 369 466 373T475 384T488 397T503 410T523 422T546 432T572 439T603 442Q729 442 740 329Q741 322 741 190V104Q741 66 743 59T754 49Q775 46 803 46H819V0H811L788 1Q764 2 737 2T699 3Q596 3 587 0H579V46H595Q656 46 656 62Q657 64 657 200Q656 335 655 343Q649 371 635 385T611 402T585 404Q540 404 506 370Q479 343 472 315T464 232V168V108Q464 78 465 68T468 55T477 49Q498 46 526 46H542V0H534L510 1Q487 2 460 2T422 3Q319 3 310 0H302V46H318Q379 46 379 62Q380 64 380 200Q379 335 378 343Q372 371 358 385T334 402T308 404Q263 404 229 370Q202 343 195 315T187 232V168V108Q187 78 188 68T191 55T200 49Q221 46 249 46H265V0H257L234 1Q210 2 183 2T145 3Q42 3 33 0H25V46H41Z"></path><path data-c="61" d="M137 305T115 305T78 320T63 359Q63 394 97 421T218 448Q291 448 336 416T396 340Q401 326 401 309T402 194V124Q402 76 407 58T428 40Q443 40 448 56T453 109V145H493V106Q492 66 490 59Q481 29 455 12T400 -6T353 12T329 54V58L327 55Q325 52 322 49T314 40T302 29T287 17T269 6T247 -2T221 -8T190 -11Q130 -11 82 20T34 107Q34 128 41 147T68 188T116 225T194 253T304 268H318V290Q318 324 312 340Q290 411 215 411Q197 411 181 410T156 406T148 403Q170 388 170 359Q170 334 154 320ZM126 106Q126 75 150 51T209 26Q247 26 276 49T315 109Q317 116 318 175Q318 233 317 233Q309 233 296 232T251 223T193 203T147 166T126 106Z" transform="translate(833,0)"></path><path data-c="78" d="M201 0Q189 3 102 3Q26 3 17 0H11V46H25Q48 47 67 52T96 61T121 78T139 96T160 122T180 150L226 210L168 288Q159 301 149 315T133 336T122 351T113 363T107 370T100 376T94 379T88 381T80 383Q74 383 44 385H16V431H23Q59 429 126 429Q219 429 229 431H237V385Q201 381 201 369Q201 367 211 353T239 315T268 274L272 270L297 304Q329 345 329 358Q329 364 327 369T322 376T317 380T310 384L307 385H302V431H309Q324 428 408 428Q487 428 493 431H499V385H492Q443 385 411 368Q394 360 377 341T312 257L296 236L358 151Q424 61 429 57T446 50Q464 46 499 46H516V0H510H502Q494 1 482 1T457 2T432 2T414 3Q403 3 377 3T327 1L304 0H295V46H298Q309 46 320 51T331 63Q331 65 291 120L250 175Q249 174 219 133T185 88Q181 83 181 74Q181 63 188 55T206 46Q208 46 208 23V0H201Z" transform="translate(1333,0)"></path></g></g></g></svg></mjx-container> 即可。</p>
<figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br><span class="line">68</span><br><span class="line">69</span><br><span class="line">70</span><br><span class="line">71</span><br><span class="line">72</span><br><span class="line">73</span><br><span class="line">74</span><br><span class="line">75</span><br><span class="line">76</span><br><span class="line">77</span><br><span class="line">78</span><br><span class="line">79</span><br><span class="line">80</span><br><span class="line">81</span><br><span class="line">82</span><br><span class="line">83</span><br><span class="line">84</span><br><span class="line">85</span><br><span class="line">86</span><br><span class="line">87</span><br><span class="line">88</span><br><span class="line">89</span><br><span class="line">90</span><br><span class="line">91</span><br><span class="line">92</span><br><span class="line">93</span><br><span class="line">94</span><br><span class="line">95</span><br><span class="line">96</span><br><span class="line">97</span><br><span class="line">98</span><br><span class="line">99</span><br><span class="line">100</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string"><bits/stdc++.h></span></span></span><br><span class="line"></span><br><span class="line"><span class="keyword">using</span> i64 = <span class="type">long</span> <span class="type">long</span>;</span><br><span class="line"></span><br><span class="line"><span class="keyword">constexpr</span> <span class="type">int</span> N = <span class="number">1e6</span> + <span class="number">50</span>;</span><br><span class="line"></span><br><span class="line"><span class="type">int</span> cnt[N];</span><br><span class="line"></span><br><span class="line"><span class="keyword">struct</span> <span class="title class_">SAM</span> {</span><br><span class="line"> <span class="type">int</span> ch[N][<span class="number">26</span>], len[N], link[N], cnt = <span class="number">1</span>, lst = <span class="number">1</span>;</span><br><span class="line"> <span class="function"><span class="type">int</span> <span class="title">expand</span><span class="params">(<span class="type">char</span> c)</span> </span>{</span><br><span class="line"> <span class="type">int</span> cur = ++cnt, d = c - <span class="string">'a'</span>;</span><br><span class="line"> len[cur] = len[lst] + <span class="number">1</span>, ::cnt[cur] = <span class="number">1</span>;</span><br><span class="line"> <span class="type">int</span> p = lst;</span><br><span class="line"> <span class="keyword">for</span> (; p && !ch[p][d]; p = link[p]) ch[p][d] = cur;</span><br><span class="line"> <span class="keyword">if</span> (!p) {</span><br><span class="line"> link[cur] = <span class="number">1</span>;</span><br><span class="line"> } <span class="keyword">else</span> {</span><br><span class="line"> <span class="type">int</span> q = ch[p][d];</span><br><span class="line"> <span class="keyword">if</span> (len[p] + <span class="number">1</span> == len[q]) {</span><br><span class="line"> link[cur] = q;</span><br><span class="line"> } <span class="keyword">else</span> {</span><br><span class="line"> <span class="type">int</span> tmp = ++cnt;</span><br><span class="line"> len[tmp] = len[p] + <span class="number">1</span>, link[tmp] = link[q];</span><br><span class="line"> <span class="built_in">memcpy</span>(ch[tmp], ch[q], <span class="built_in">sizeof</span>(ch[tmp]));</span><br><span class="line"> <span class="keyword">for</span> (; p && ch[p][d] == q; p = link[p]) ch[p][d] = tmp;</span><br><span class="line"> link[cur] = link[q] = tmp;</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">return</span> lst = cur;</span><br><span class="line"> }</span><br><span class="line">} sam;</span><br><span class="line"></span><br><span class="line"><span class="type">int</span> n, a[N];</span><br><span class="line"><span class="type">char</span> s[N];</span><br><span class="line"></span><br><span class="line">std::vector<<span class="type">int</span>> adj[N];</span><br><span class="line">i64 sum[N];</span><br><span class="line"><span class="type">int</span> mx[N], smx[N], mn[N], smn[N]; <span class="comment">// `s` stands for `semi`</span></span><br><span class="line"></span><br><span class="line">i64 ans[N];</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="type">void</span> <span class="title">chkmax</span><span class="params">(<span class="type">int</span> u, <span class="type">int</span> w)</span> </span>{</span><br><span class="line"> <span class="keyword">if</span> (w >= mx[u]) smx[u] = mx[u], mx[u] = w;</span><br><span class="line"> <span class="keyword">else</span> <span class="keyword">if</span> (w > smx[u]) smx[u] = w;</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="type">void</span> <span class="title">chkmin</span><span class="params">(<span class="type">int</span> u, <span class="type">int</span> w)</span> </span>{</span><br><span class="line"> <span class="keyword">if</span> (w <= mn[u]) smn[u] = mn[u], mn[u] = w;</span><br><span class="line"> <span class="keyword">else</span> <span class="keyword">if</span> (w < smn[u]) smn[u] = w;</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">dfs</span><span class="params">(<span class="type">int</span> u)</span> </span>{</span><br><span class="line"> <span class="type">int</span> t = <span class="number">0</span>;</span><br><span class="line"> <span class="keyword">for</span> (<span class="keyword">auto</span> v : adj[u]) {</span><br><span class="line"> <span class="built_in">dfs</span>(v), t += cnt[v];</span><br><span class="line"> <span class="built_in">chkmax</span>(u, mx[v]), <span class="built_in">chkmax</span>(u, smx[v]);</span><br><span class="line"> <span class="built_in">chkmin</span>(u, mn[v]), <span class="built_in">chkmin</span>(u, smn[v]);</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">if</span> (t + cnt[u] < <span class="number">2</span>) <span class="keyword">return</span> cnt[u] += t, <span class="built_in">void</span>();</span><br><span class="line"> i64 &p = ans[sam.len[u]];</span><br><span class="line"> p = std::<span class="built_in">max</span>({p, <span class="number">1ll</span> * mx[u] * smx[u], <span class="number">1ll</span> * mn[u] * smn[u]});</span><br><span class="line"> <span class="keyword">for</span> (<span class="keyword">auto</span> v : adj[u]) {</span><br><span class="line"> sum[sam.len[u]] += <span class="number">1ll</span> * cnt[u] * cnt[v];</span><br><span class="line"> cnt[u] += cnt[v];</span><br><span class="line"> }</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">solve</span><span class="params">()</span> </span>{</span><br><span class="line"> <span class="built_in">memset</span>(mx, <span class="number">-0x3f</span>, <span class="built_in">sizeof</span>(mx)), <span class="built_in">memset</span>(smx, <span class="number">-0x3f</span>, <span class="built_in">sizeof</span>(mx));</span><br><span class="line"> <span class="built_in">memset</span>(mn, <span class="number">0x3f</span>, <span class="built_in">sizeof</span>(mn)), <span class="built_in">memset</span>(smn, <span class="number">0x3f</span>, <span class="built_in">sizeof</span>(mn));</span><br><span class="line"> <span class="built_in">memset</span>(ans, <span class="number">-0x3f</span>, <span class="built_in">sizeof</span>(ans));</span><br><span class="line"> </span><br><span class="line"> std::cin >> n >> (s + <span class="number">1</span>);</span><br><span class="line"> <span class="keyword">for</span> (<span class="type">int</span> i = <span class="number">1</span>; i <= n; i++) std::cin >> a[i];</span><br><span class="line"></span><br><span class="line"> <span class="keyword">for</span> (<span class="type">int</span> i = n; i >= <span class="number">1</span>; i--) {</span><br><span class="line"> <span class="type">int</span> p = sam.<span class="built_in">expand</span>(s[i]);</span><br><span class="line"> mx[p] = mn[p] = a[i];</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">for</span> (<span class="type">int</span> i = <span class="number">2</span>; i <= sam.cnt; i++) adj[sam.link[i]].<span class="built_in">push_back</span>(i);</span><br><span class="line"></span><br><span class="line"> <span class="built_in">dfs</span>(<span class="number">1</span>);</span><br><span class="line"> <span class="keyword">for</span> (<span class="type">int</span> i = n - <span class="number">1</span>; ~i; i--) {</span><br><span class="line"> sum[i] += sum[i + <span class="number">1</span>];</span><br><span class="line"> ans[i] = std::<span class="built_in">max</span>(ans[i], ans[i + <span class="number">1</span>]);</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">for</span> (<span class="type">int</span> i = <span class="number">0</span>; i < n; i++) {</span><br><span class="line"> std::cout << sum[i] << <span class="string">" "</span> << (sum[i] ? ans[i] : <span class="number">0</span>) << <span class="string">"\n"</span>;</span><br><span class="line"> }</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">signed</span> <span class="title">main</span><span class="params">()</span> </span>{</span><br><span class="line"> std::cin.<span class="built_in">tie</span>(<span class="literal">nullptr</span>)-><span class="built_in">sync_with_stdio</span>(<span class="literal">false</span>);</span><br><span class="line"></span><br><span class="line"> <span class="type">int</span> t = <span class="number">1</span>;</span><br><span class="line"> <span class="comment">// std::cin >> t;</span></span><br><span class="line"> <span class="keyword">while</span> (t--) <span class="built_in">solve</span>();</span><br><span class="line"> </span><br><span class="line"> <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">}</span><br></pre></td></tr></table></figure>
</div></article></div><div class="card"><article class="card-content article" role="article"><div class="article-meta is-size-7 is-uppercase level is-mobile"><div class="level-left"><span class="level-item"><time dateTime="2024-01-21T10:23:58.000Z" title="2024/1/21 18:23:58">2024-01-21</time>发表</span><span class="level-item"><time dateTime="2024-01-22T07:00:07.126Z" title="2024/1/22 15:00:07">2024-01-22</time>更新</span><span class="level-item"><a class="link-muted" href="/categories/%E9%A2%98%E8%A7%A3/">题解</a><span> / </span><a class="link-muted" href="/categories/%E9%A2%98%E8%A7%A3/Codeforces/">Codeforces</a></span><span class="level-item">5 分钟读完 (大约785个字)</span></div></div><p class="title is-3 is-size-4-mobile"><a class="link-muted" href="/2024/01/21/CF1073G-Yet-Another-LCP-Problem/">CF1073G Yet Another LCP Problem</a></p><div class="content"><p>还算有点意思。</p>
<p>把原字符串倒过来建一个 SAM,则我们熟知两个后缀的 LCP 就是其对应节点在 link 树上 LCA 的 <code>len</code> 值。</p>
<p>然后考虑 DP。这类问题的普遍套路是钦定某一个点是 LCA 然后对每个点计算贡献。我们设 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.464ex;" xmlns="http://www.w3.org/2000/svg" width="1.848ex" height="2.059ex" role="img" focusable="false" viewBox="0 -705 817 910"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="msub"><g data-mml-node="mi"><path data-c="1D453" d="M118 -162Q120 -162 124 -164T135 -167T147 -168Q160 -168 171 -155T187 -126Q197 -99 221 27T267 267T289 382V385H242Q195 385 192 387Q188 390 188 397L195 425Q197 430 203 430T250 431Q298 431 298 432Q298 434 307 482T319 540Q356 705 465 705Q502 703 526 683T550 630Q550 594 529 578T487 561Q443 561 443 603Q443 622 454 636T478 657L487 662Q471 668 457 668Q445 668 434 658T419 630Q412 601 403 552T387 469T380 433Q380 431 435 431Q480 431 487 430T498 424Q499 420 496 407T491 391Q489 386 482 386T428 385H372L349 263Q301 15 282 -47Q255 -132 212 -173Q175 -205 139 -205Q107 -205 81 -186T55 -132Q55 -95 76 -78T118 -61Q162 -61 162 -103Q162 -122 151 -136T127 -157L118 -162Z"></path></g><g data-mml-node="mi" transform="translate(523,-150) scale(0.707)"><path data-c="1D456" d="M184 600Q184 624 203 642T247 661Q265 661 277 649T290 619Q290 596 270 577T226 557Q211 557 198 567T184 600ZM21 287Q21 295 30 318T54 369T98 420T158 442Q197 442 223 419T250 357Q250 340 236 301T196 196T154 83Q149 61 149 51Q149 26 166 26Q175 26 185 29T208 43T235 78T260 137Q263 149 265 151T282 153Q302 153 302 143Q302 135 293 112T268 61T223 11T161 -11Q129 -11 102 10T74 74Q74 91 79 106T122 220Q160 321 166 341T173 380Q173 404 156 404H154Q124 404 99 371T61 287Q60 286 59 284T58 281T56 279T53 278T49 278T41 278H27Q21 284 21 287Z"></path></g></g></g></g></svg></mjx-container> 表示 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.025ex;" xmlns="http://www.w3.org/2000/svg" width="0.781ex" height="1.52ex" role="img" focusable="false" viewBox="0 -661 345 672"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="mi"><path data-c="1D456" d="M184 600Q184 624 203 642T247 661Q265 661 277 649T290 619Q290 596 270 577T226 557Q211 557 198 567T184 600ZM21 287Q21 295 30 318T54 369T98 420T158 442Q197 442 223 419T250 357Q250 340 236 301T196 196T154 83Q149 61 149 51Q149 26 166 26Q175 26 185 29T208 43T235 78T260 137Q263 149 265 151T282 153Q302 153 302 143Q302 135 293 112T268 61T223 11T161 -11Q129 -11 102 10T74 74Q74 91 79 106T122 220Q160 321 166 341T173 380Q173 404 156 404H154Q124 404 99 371T61 287Q60 286 59 284T58 281T56 279T53 278T49 278T41 278H27Q21 284 21 287Z"></path></g></g></g></svg></mjx-container> 子树内属于集合 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: 0;" xmlns="http://www.w3.org/2000/svg" width="1.697ex" height="1.62ex" role="img" focusable="false" viewBox="0 -716 750 716"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="mi"><path data-c="1D434" d="M208 74Q208 50 254 46Q272 46 272 35Q272 34 270 22Q267 8 264 4T251 0Q249 0 239 0T205 1T141 2Q70 2 50 0H42Q35 7 35 11Q37 38 48 46H62Q132 49 164 96Q170 102 345 401T523 704Q530 716 547 716H555H572Q578 707 578 706L606 383Q634 60 636 57Q641 46 701 46Q726 46 726 36Q726 34 723 22Q720 7 718 4T704 0Q701 0 690 0T651 1T578 2Q484 2 455 0H443Q437 6 437 9T439 27Q443 40 445 43L449 46H469Q523 49 533 63L521 213H283L249 155Q208 86 208 74ZM516 260Q516 271 504 416T490 562L463 519Q447 492 400 412L310 260L413 259Q516 259 516 260Z"></path></g></g></g></svg></mjx-container> 的点的个数,<mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.464ex;" xmlns="http://www.w3.org/2000/svg" width="1.819ex" height="1.464ex" role="img" focusable="false" viewBox="0 -442 804 647"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="msub"><g data-mml-node="mi"><path data-c="1D454" d="M311 43Q296 30 267 15T206 0Q143 0 105 45T66 160Q66 265 143 353T314 442Q361 442 401 394L404 398Q406 401 409 404T418 412T431 419T447 422Q461 422 470 413T480 394Q480 379 423 152T363 -80Q345 -134 286 -169T151 -205Q10 -205 10 -137Q10 -111 28 -91T74 -71Q89 -71 102 -80T116 -111Q116 -121 114 -130T107 -144T99 -154T92 -162L90 -164H91Q101 -167 151 -167Q189 -167 211 -155Q234 -144 254 -122T282 -75Q288 -56 298 -13Q311 35 311 43ZM384 328L380 339Q377 350 375 354T369 368T359 382T346 393T328 402T306 405Q262 405 221 352Q191 313 171 233T151 117Q151 38 213 38Q269 38 323 108L331 118L384 328Z"></path></g><g data-mml-node="mi" transform="translate(510,-150) scale(0.707)"><path data-c="1D456" d="M184 600Q184 624 203 642T247 661Q265 661 277 649T290 619Q290 596 270 577T226 557Q211 557 198 567T184 600ZM21 287Q21 295 30 318T54 369T98 420T158 442Q197 442 223 419T250 357Q250 340 236 301T196 196T154 83Q149 61 149 51Q149 26 166 26Q175 26 185 29T208 43T235 78T260 137Q263 149 265 151T282 153Q302 153 302 143Q302 135 293 112T268 61T223 11T161 -11Q129 -11 102 10T74 74Q74 91 79 106T122 220Q160 321 166 341T173 380Q173 404 156 404H154Q124 404 99 371T61 287Q60 286 59 284T58 281T56 279T53 278T49 278T41 278H27Q21 284 21 287Z"></path></g></g></g></g></svg></mjx-container> 表示 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.462ex;" xmlns="http://www.w3.org/2000/svg" width="0.932ex" height="1.957ex" role="img" focusable="false" viewBox="0 -661 412 865"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="mi"><path data-c="1D457" d="M297 596Q297 627 318 644T361 661Q378 661 389 651T403 623Q403 595 384 576T340 557Q322 557 310 567T297 596ZM288 376Q288 405 262 405Q240 405 220 393T185 362T161 325T144 293L137 279Q135 278 121 278H107Q101 284 101 286T105 299Q126 348 164 391T252 441Q253 441 260 441T272 442Q296 441 316 432Q341 418 354 401T367 348V332L318 133Q267 -67 264 -75Q246 -125 194 -164T75 -204Q25 -204 7 -183T-12 -137Q-12 -110 7 -91T53 -71Q70 -71 82 -81T95 -112Q95 -148 63 -167Q69 -168 77 -168Q111 -168 139 -140T182 -74L193 -32Q204 11 219 72T251 197T278 308T289 365Q289 372 288 376Z"></path></g></g></g></svg></mjx-container> 子树内属于集合 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: 0;" xmlns="http://www.w3.org/2000/svg" width="1.717ex" height="1.545ex" role="img" focusable="false" viewBox="0 -683 759 683"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="mi"><path data-c="1D435" d="M231 637Q204 637 199 638T194 649Q194 676 205 682Q206 683 335 683Q594 683 608 681Q671 671 713 636T756 544Q756 480 698 429T565 360L555 357Q619 348 660 311T702 219Q702 146 630 78T453 1Q446 0 242 0Q42 0 39 2Q35 5 35 10Q35 17 37 24Q42 43 47 45Q51 46 62 46H68Q95 46 128 49Q142 52 147 61Q150 65 219 339T288 628Q288 635 231 637ZM649 544Q649 574 634 600T585 634Q578 636 493 637Q473 637 451 637T416 636H403Q388 635 384 626Q382 622 352 506Q352 503 351 500L320 374H401Q482 374 494 376Q554 386 601 434T649 544ZM595 229Q595 273 572 302T512 336Q506 337 429 337Q311 337 310 336Q310 334 293 263T258 122L240 52Q240 48 252 48T333 46Q422 46 429 47Q491 54 543 105T595 229Z"></path></g></g></g></svg></mjx-container> 的点的个数,显然一对合法的点的 LCA 是 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.025ex;" xmlns="http://www.w3.org/2000/svg" width="0.781ex" height="1.52ex" role="img" focusable="false" viewBox="0 -661 345 672"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="mi"><path data-c="1D456" d="M184 600Q184 624 203 642T247 661Q265 661 277 649T290 619Q290 596 270 577T226 557Q211 557 198 567T184 600ZM21 287Q21 295 30 318T54 369T98 420T158 442Q197 442 223 419T250 357Q250 340 236 301T196 196T154 83Q149 61 149 51Q149 26 166 26Q175 26 185 29T208 43T235 78T260 137Q263 149 265 151T282 153Q302 153 302 143Q302 135 293 112T268 61T223 11T161 -11Q129 -11 102 10T74 74Q74 91 79 106T122 220Q160 321 166 341T173 380Q173 404 156 404H154Q124 404 99 371T61 287Q60 286 59 284T58 281T56 279T53 278T49 278T41 278H27Q21 284 21 287Z"></path></g></g></g></svg></mjx-container> 当且仅当它们在 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.025ex;" xmlns="http://www.w3.org/2000/svg" width="0.781ex" height="1.52ex" role="img" focusable="false" viewBox="0 -661 345 672"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="mi"><path data-c="1D456" d="M184 600Q184 624 203 642T247 661Q265 661 277 649T290 619Q290 596 270 577T226 557Q211 557 198 567T184 600ZM21 287Q21 295 30 318T54 369T98 420T158 442Q197 442 223 419T250 357Q250 340 236 301T196 196T154 83Q149 61 149 51Q149 26 166 26Q175 26 185 29T208 43T235 78T260 137Q263 149 265 151T282 153Q302 153 302 143Q302 135 293 112T268 61T223 11T161 -11Q129 -11 102 10T74 74Q74 91 79 106T122 220Q160 321 166 341T173 380Q173 404 156 404H154Q124 404 99 371T61 287Q60 286 59 284T58 281T56 279T53 278T49 278T41 278H27Q21 284 21 287Z"></path></g></g></g></svg></mjx-container> 的不同子树中,因此,我们便有如下方程:</p>
<p><mjx-container class="MathJax" jax="SVG" display="true"><svg style="vertical-align: -3.222ex;" xmlns="http://www.w3.org/2000/svg" width="49.409ex" height="5.371ex" role="img" focusable="false" viewBox="0 -950 21838.7 2374.1"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="mi"><path data-c="1D44E" d="M33 157Q33 258 109 349T280 441Q331 441 370 392Q386 422 416 422Q429 422 439 414T449 394Q449 381 412 234T374 68Q374 43 381 35T402 26Q411 27 422 35Q443 55 463 131Q469 151 473 152Q475 153 483 153H487Q506 153 506 144Q506 138 501 117T481 63T449 13Q436 0 417 -8Q409 -10 393 -10Q359 -10 336 5T306 36L300 51Q299 52 296 50Q294 48 292 46Q233 -10 172 -10Q117 -10 75 30T33 157ZM351 328Q351 334 346 350T323 385T277 405Q242 405 210 374T160 293Q131 214 119 129Q119 126 119 118T118 106Q118 61 136 44T179 26Q217 26 254 59T298 110Q300 114 325 217T351 328Z"></path></g><g data-mml-node="mi" transform="translate(529,0)"><path data-c="1D45B" d="M21 287Q22 293 24 303T36 341T56 388T89 425T135 442Q171 442 195 424T225 390T231 369Q231 367 232 367L243 378Q304 442 382 442Q436 442 469 415T503 336T465 179T427 52Q427 26 444 26Q450 26 453 27Q482 32 505 65T540 145Q542 153 560 153Q580 153 580 145Q580 144 576 130Q568 101 554 73T508 17T439 -10Q392 -10 371 17T350 73Q350 92 386 193T423 345Q423 404 379 404H374Q288 404 229 303L222 291L189 157Q156 26 151 16Q138 -11 108 -11Q95 -11 87 -5T76 7T74 17Q74 30 112 180T152 343Q153 348 153 366Q153 405 129 405Q91 405 66 305Q60 285 60 284Q58 278 41 278H27Q21 284 21 287Z"></path></g><g data-mml-node="mi" transform="translate(1129,0)"><path data-c="1D460" d="M131 289Q131 321 147 354T203 415T300 442Q362 442 390 415T419 355Q419 323 402 308T364 292Q351 292 340 300T328 326Q328 342 337 354T354 372T367 378Q368 378 368 379Q368 382 361 388T336 399T297 405Q249 405 227 379T204 326Q204 301 223 291T278 274T330 259Q396 230 396 163Q396 135 385 107T352 51T289 7T195 -10Q118 -10 86 19T53 87Q53 126 74 143T118 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<p>直接做会退化成 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.566ex;" xmlns="http://www.w3.org/2000/svg" width="5.959ex" height="2.262ex" role="img" focusable="false" viewBox="0 -750 2634 1000"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="TeXAtom" data-mjx-texclass="ORD"><g data-mml-node="mi"><path data-c="4F" d="M308 428Q289 428 289 438Q289 457 318 508T378 593Q417 638 475 671T599 705Q688 705 732 643T777 483Q777 380 733 285T620 123T464 18T293 -22Q188 -22 123 51T58 245Q58 327 87 403T159 533T249 626T333 685T388 705Q404 705 404 693Q404 674 363 649Q333 632 304 606T239 537T181 429T158 290Q158 179 214 114T364 48Q489 48 583 165T677 438Q677 473 670 505T648 568T601 617T528 636Q518 636 513 635Q486 629 460 600T419 544T392 490Q383 470 372 459Q341 430 308 428Z"></path></g></g><g data-mml-node="mo" transform="translate(796,0)"><path data-c="28" d="M94 250Q94 319 104 381T127 488T164 576T202 643T244 695T277 729T302 750H315H319Q333 750 333 741Q333 738 316 720T275 667T226 581T184 443T167 250T184 58T225 -81T274 -167T316 -220T333 -241Q333 -250 318 -250H315H302L274 -226Q180 -141 137 -14T94 250Z"></path></g><g data-mml-node="mi" transform="translate(1185,0)"><path data-c="1D45E" d="M33 157Q33 258 109 349T280 441Q340 441 372 389Q373 390 377 395T388 406T404 418Q438 442 450 442Q454 442 457 439T460 434Q460 425 391 149Q320 -135 320 -139Q320 -147 365 -148H390Q396 -156 396 -157T393 -175Q389 -188 383 -194H370Q339 -192 262 -192Q234 -192 211 -192T174 -192T157 -193Q143 -193 143 -185Q143 -182 145 -170Q149 -154 152 -151T172 -148Q220 -148 230 -141Q238 -136 258 -53T279 32Q279 33 272 29Q224 -10 172 -10Q117 -10 75 30T33 157ZM352 326Q329 405 277 405Q242 405 210 374T160 293Q131 214 119 129Q119 126 119 118T118 106Q118 61 136 44T179 26Q233 26 290 98L298 109L352 326Z"></path></g><g data-mml-node="mi" transform="translate(1645,0)"><path data-c="1D45B" d="M21 287Q22 293 24 303T36 341T56 388T89 425T135 442Q171 442 195 424T225 390T231 369Q231 367 232 367L243 378Q304 442 382 442Q436 442 469 415T503 336T465 179T427 52Q427 26 444 26Q450 26 453 27Q482 32 505 65T540 145Q542 153 560 153Q580 153 580 145Q580 144 576 130Q568 101 554 73T508 17T439 -10Q392 -10 371 17T350 73Q350 92 386 193T423 345Q423 404 379 404H374Q288 404 229 303L222 291L189 157Q156 26 151 16Q138 -11 108 -11Q95 -11 87 -5T76 7T74 17Q74 30 112 180T152 343Q153 348 153 366Q153 405 129 405Q91 405 66 305Q60 285 60 284Q58 278 41 278H27Q21 284 21 287Z"></path></g><g data-mml-node="mo" transform="translate(2245,0)"><path data-c="29" d="M60 749L64 750Q69 750 74 750H86L114 726Q208 641 251 514T294 250Q294 182 284 119T261 12T224 -76T186 -143T145 -194T113 -227T90 -246Q87 -249 86 -250H74Q66 -250 63 -250T58 -247T55 -238Q56 -237 66 -225Q221 -64 221 250T66 725Q56 737 55 738Q55 746 60 749Z"></path></g></g></g></svg></mjx-container>,但考虑到 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.566ex;" xmlns="http://www.w3.org/2000/svg" width="5.721ex" height="2.262ex" role="img" focusable="false" viewBox="0 -750 2528.7 1000"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="mo"><path data-c="2211" d="M61 748Q64 750 489 750H913L954 640Q965 609 976 579T993 533T999 516H979L959 517Q936 579 886 621T777 682Q724 700 655 705T436 710H319Q183 710 183 709Q186 706 348 484T511 259Q517 250 513 244L490 216Q466 188 420 134T330 27L149 -187Q149 -188 362 -188Q388 -188 436 -188T506 -189Q679 -189 778 -162T936 -43Q946 -27 959 6H999L913 -249L489 -250Q65 -250 62 -248Q56 -246 56 -239Q56 -234 118 -161Q186 -81 245 -11L428 206Q428 207 242 462L57 717L56 728Q56 744 61 748Z"></path></g><g data-mml-node="mo" transform="translate(1222.7,0) translate(0 -0.5)"><path data-c="7C" d="M139 -249H137Q125 -249 119 -235V251L120 737Q130 750 139 750Q152 750 159 735V-235Q151 -249 141 -249H139Z"></path></g><g data-mml-node="mi" transform="translate(1500.7,0)"><path data-c="1D434" d="M208 74Q208 50 254 46Q272 46 272 35Q272 34 270 22Q267 8 264 4T251 0Q249 0 239 0T205 1T141 2Q70 2 50 0H42Q35 7 35 11Q37 38 48 46H62Q132 49 164 96Q170 102 345 401T523 704Q530 716 547 716H555H572Q578 707 578 706L606 383Q634 60 636 57Q641 46 701 46Q726 46 726 36Q726 34 723 22Q720 7 718 4T704 0Q701 0 690 0T651 1T578 2Q484 2 455 0H443Q437 6 437 9T439 27Q443 40 445 43L449 46H469Q523 49 533 63L521 213H283L249 155Q208 86 208 74ZM516 260Q516 271 504 416T490 562L463 519Q447 492 400 412L310 260L413 259Q516 259 516 260Z"></path></g><g data-mml-node="mo" transform="translate(2250.7,0) translate(0 -0.5)"><path data-c="7C" d="M139 -249H137Q125 -249 119 -235V251L120 737Q130 750 139 750Q152 750 159 735V-235Q151 -249 141 -249H139Z"></path></g></g></g></svg></mjx-container> 及 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.566ex;" xmlns="http://www.w3.org/2000/svg" width="5.741ex" height="2.262ex" role="img" focusable="false" viewBox="0 -750 2537.7 1000"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="mo"><path data-c="2211" d="M61 748Q64 750 489 750H913L954 640Q965 609 976 579T993 533T999 516H979L959 517Q936 579 886 621T777 682Q724 700 655 705T436 710H319Q183 710 183 709Q186 706 348 484T511 259Q517 250 513 244L490 216Q466 188 420 134T330 27L149 -187Q149 -188 362 -188Q388 -188 436 -188T506 -189Q679 -189 778 -162T936 -43Q946 -27 959 6H999L913 -249L489 -250Q65 -250 62 -248Q56 -246 56 -239Q56 -234 118 -161Q186 -81 245 -11L428 206Q428 207 242 462L57 717L56 728Q56 744 61 748Z"></path></g><g data-mml-node="mo" transform="translate(1222.7,0) translate(0 -0.5)"><path data-c="7C" d="M139 -249H137Q125 -249 119 -235V251L120 737Q130 750 139 750Q152 750 159 735V-235Q151 -249 141 -249H139Z"></path></g><g data-mml-node="mi" transform="translate(1500.7,0)"><path data-c="1D435" d="M231 637Q204 637 199 638T194 649Q194 676 205 682Q206 683 335 683Q594 683 608 681Q671 671 713 636T756 544Q756 480 698 429T565 360L555 357Q619 348 660 311T702 219Q702 146 630 78T453 1Q446 0 242 0Q42 0 39 2Q35 5 35 10Q35 17 37 24Q42 43 47 45Q51 46 62 46H68Q95 46 128 49Q142 52 147 61Q150 65 219 339T288 628Q288 635 231 637ZM649 544Q649 574 634 600T585 634Q578 636 493 637Q473 637 451 637T416 636H403Q388 635 384 626Q382 622 352 506Q352 503 351 500L320 374H401Q482 374 494 376Q554 386 601 434T649 544ZM595 229Q595 273 572 302T512 336Q506 337 429 337Q311 337 310 336Q310 334 293 263T258 122L240 52Q240 48 252 48T333 46Q422 46 429 47Q491 54 543 105T595 229Z"></path></g><g data-mml-node="mo" transform="translate(2259.7,0) translate(0 -0.5)"><path data-c="7C" d="M139 -249H137Q125 -249 119 -235V251L120 737Q130 750 139 750Q152 750 159 735V-235Q151 -249 141 -249H139Z"></path></g></g></g></svg></mjx-container> 的量级都为 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.05ex;" xmlns="http://www.w3.org/2000/svg" width="7.147ex" height="2.005ex" role="img" focusable="false" viewBox="0 -864 3159 886"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="mn"><path data-c="32" d="M109 429Q82 429 66 447T50 491Q50 562 103 614T235 666Q326 666 387 610T449 465Q449 422 429 383T381 315T301 241Q265 210 201 149L142 93L218 92Q375 92 385 97Q392 99 409 186V189H449V186Q448 183 436 95T421 3V0H50V19V31Q50 38 56 46T86 81Q115 113 136 137Q145 147 170 174T204 211T233 244T261 278T284 308T305 340T320 369T333 401T340 431T343 464Q343 527 309 573T212 619Q179 619 154 602T119 569T109 550Q109 549 114 549Q132 549 151 535T170 489Q170 464 154 447T109 429Z"></path></g><g data-mml-node="mo" transform="translate(722.2,0)"><path data-c="D7" d="M630 29Q630 9 609 9Q604 9 587 25T493 118L389 222L284 117Q178 13 175 11Q171 9 168 9Q160 9 154 15T147 29Q147 36 161 51T255 146L359 250L255 354Q174 435 161 449T147 471Q147 480 153 485T168 490Q173 490 175 489Q178 487 284 383L389 278L493 382Q570 459 587 475T609 491Q630 491 630 471Q630 464 620 453T522 355L418 250L522 145Q606 61 618 48T630 29Z"></path></g><g data-mml-node="msup" transform="translate(1722.4,0)"><g data-mml-node="mn"><path data-c="31" d="M213 578L200 573Q186 568 160 563T102 556H83V602H102Q149 604 189 617T245 641T273 663Q275 666 285 666Q294 666 302 660V361L303 61Q310 54 315 52T339 48T401 46H427V0H416Q395 3 257 3Q121 3 100 0H88V46H114Q136 46 152 46T177 47T193 50T201 52T207 57T213 61V578Z"></path><path data-c="30" d="M96 585Q152 666 249 666Q297 666 345 640T423 548Q460 465 460 320Q460 165 417 83Q397 41 362 16T301 -15T250 -22Q224 -22 198 -16T137 16T82 83Q39 165 39 320Q39 494 96 585ZM321 597Q291 629 250 629Q208 629 178 597Q153 571 145 525T137 333Q137 175 145 125T181 46Q209 16 250 16Q290 16 318 46Q347 76 354 130T362 333Q362 478 354 524T321 597Z" transform="translate(500,0)"></path></g><g data-mml-node="mn" transform="translate(1033,393.1) scale(0.707)"><path data-c="35" d="M164 157Q164 133 148 117T109 101H102Q148 22 224 22Q294 22 326 82Q345 115 345 210Q345 313 318 349Q292 382 260 382H254Q176 382 136 314Q132 307 129 306T114 304Q97 304 95 310Q93 314 93 485V614Q93 664 98 664Q100 666 102 666Q103 666 123 658T178 642T253 634Q324 634 389 662Q397 666 402 666Q410 666 410 648V635Q328 538 205 538Q174 538 149 544L139 546V374Q158 388 169 396T205 412T256 420Q337 420 393 355T449 201Q449 109 385 44T229 -22Q148 -22 99 32T50 154Q50 178 61 192T84 210T107 214Q132 214 148 197T164 157Z"></path></g></g></g></g></svg></mjx-container>,因此我们可以考虑建出虚树然后再 DP,这样复杂度就对了。</p>
<p>注意清空虚树的邻接表以及 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.464ex;" xmlns="http://www.w3.org/2000/svg" width="1.244ex" height="2.059ex" role="img" focusable="false" viewBox="0 -705 550 910"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="mi"><path data-c="1D453" d="M118 -162Q120 -162 124 -164T135 -167T147 -168Q160 -168 171 -155T187 -126Q197 -99 221 27T267 267T289 382V385H242Q195 385 192 387Q188 390 188 397L195 425Q197 430 203 430T250 431Q298 431 298 432Q298 434 307 482T319 540Q356 705 465 705Q502 703 526 683T550 630Q550 594 529 578T487 561Q443 561 443 603Q443 622 454 636T478 657L487 662Q471 668 457 668Q445 668 434 658T419 630Q412 601 403 552T387 469T380 433Q380 431 435 431Q480 431 487 430T498 424Q499 420 496 407T491 391Q489 386 482 386T428 385H372L349 263Q301 15 282 -47Q255 -132 212 -173Q175 -205 139 -205Q107 -205 81 -186T55 -132Q55 -95 76 -78T118 -61Q162 -61 162 -103Q162 -122 151 -136T127 -157L118 -162Z"></path></g></g></g></svg></mjx-container> 与 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.464ex;" xmlns="http://www.w3.org/2000/svg" width="1.079ex" height="1.464ex" role="img" focusable="false" viewBox="0 -442 477 647"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="mi"><path data-c="1D454" d="M311 43Q296 30 267 15T206 0Q143 0 105 45T66 160Q66 265 143 353T314 442Q361 442 401 394L404 398Q406 401 409 404T418 412T431 419T447 422Q461 422 470 413T480 394Q480 379 423 152T363 -80Q345 -134 286 -169T151 -205Q10 -205 10 -137Q10 -111 28 -91T74 -71Q89 -71 102 -80T116 -111Q116 -121 114 -130T107 -144T99 -154T92 -162L90 -164H91Q101 -167 151 -167Q189 -167 211 -155Q234 -144 254 -122T282 -75Q288 -56 298 -13Q311 35 311 43ZM384 328L380 339Q377 350 375 354T369 368T359 382T346 393T328 402T306 405Q262 405 221 352Q191 313 171 233T151 117Q151 38 213 38Q269 38 323 108L331 118L384 328Z"></path></g></g></g></svg></mjx-container>。</p>
<figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br><span class="line">68</span><br><span class="line">69</span><br><span class="line">70</span><br><span class="line">71</span><br><span class="line">72</span><br><span class="line">73</span><br><span class="line">74</span><br><span class="line">75</span><br><span class="line">76</span><br><span class="line">77</span><br><span class="line">78</span><br><span class="line">79</span><br><span class="line">80</span><br><span class="line">81</span><br><span class="line">82</span><br><span class="line">83</span><br><span class="line">84</span><br><span class="line">85</span><br><span class="line">86</span><br><span class="line">87</span><br><span class="line">88</span><br><span class="line">89</span><br><span class="line">90</span><br><span class="line">91</span><br><span class="line">92</span><br><span class="line">93</span><br><span class="line">94</span><br><span class="line">95</span><br><span class="line">96</span><br><span class="line">97</span><br><span class="line">98</span><br><span class="line">99</span><br><span class="line">100</span><br><span class="line">101</span><br><span class="line">102</span><br><span class="line">103</span><br><span class="line">104</span><br><span class="line">105</span><br><span class="line">106</span><br><span class="line">107</span><br><span class="line">108</span><br><span class="line">109</span><br><span class="line">110</span><br><span class="line">111</span><br><span class="line">112</span><br><span class="line">113</span><br><span class="line">114</span><br><span class="line">115</span><br><span class="line">116</span><br><span class="line">117</span><br><span class="line">118</span><br><span class="line">119</span><br><span class="line">120</span><br><span class="line">121</span><br><span class="line">122</span><br><span class="line">123</span><br><span class="line">124</span><br><span class="line">125</span><br><span class="line">126</span><br><span class="line">127</span><br><span class="line">128</span><br><span class="line">129</span><br><span class="line">130</span><br><span class="line">131</span><br><span class="line">132</span><br><span class="line">133</span><br><span class="line">134</span><br><span class="line">135</span><br><span class="line">136</span><br><span class="line">137</span><br><span class="line">138</span><br><span class="line">139</span><br><span class="line">140</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string"><bits/stdc++.h></span></span></span><br><span class="line"></span><br><span class="line"><span class="keyword">using</span> i64 = <span class="type">long</span> <span class="type">long</span>;</span><br><span class="line"><span class="keyword">using</span> u32 = <span class="type">unsigned</span>;</span><br><span class="line"></span><br><span class="line"><span class="keyword">template</span> <<span class="keyword">typename</span> T = <span class="type">int</span>></span><br><span class="line"><span class="keyword">inline</span> T <span class="built_in">read</span>() {</span><br><span class="line"> T res;</span><br><span class="line"> std::cin >> res;</span><br><span class="line"> <span class="keyword">return</span> res;</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"><span class="keyword">constexpr</span> <span class="type">int</span> N = <span class="number">4e5</span> + <span class="number">50</span>;</span><br><span class="line"></span><br><span class="line"><span class="type">int</span> n, m;</span><br><span class="line"><span class="type">char</span> s[N];</span><br><span class="line"></span><br><span class="line"><span class="type">int</span> pos[N];</span><br><span class="line"></span><br><span class="line"><span class="keyword">struct</span> <span class="title class_">SAM</span> {</span><br><span class="line"> <span class="type">int</span> ch[N][<span class="number">26</span>], link[N], len[N], cnt = <span class="number">1</span>, lst = <span class="number">1</span>;</span><br><span class="line"> <span class="function"><span class="type">int</span> <span class="title">expand</span><span class="params">(<span class="type">int</span> d)</span> </span>{</span><br><span class="line"> <span class="type">int</span> cur = ++cnt;</span><br><span class="line"> len[cur] = len[lst] + <span class="number">1</span>;</span><br><span class="line"> <span class="type">int</span> p = lst;</span><br><span class="line"> <span class="keyword">for</span> (; p && !ch[p][d]; p = link[p]) ch[p][d] = cur;</span><br><span class="line"> <span class="keyword">if</span> (!p) {</span><br><span class="line"> link[cur] = <span class="number">1</span>;</span><br><span class="line"> } <span class="keyword">else</span> {</span><br><span class="line"> <span class="type">int</span> q = ch[p][d];</span><br><span class="line"> <span class="keyword">if</span> (len[p] + <span class="number">1</span> == len[q]) {</span><br><span class="line"> link[cur] = q;</span><br><span class="line"> } <span class="keyword">else</span> {</span><br><span class="line"> <span class="type">int</span> tmp = ++cnt;</span><br><span class="line"> len[tmp] = len[p] + <span class="number">1</span>, link[tmp] = link[q];</span><br><span class="line"> <span class="built_in">memcpy</span>(ch[tmp], ch[q], <span class="built_in">sizeof</span>(ch[q]));</span><br><span class="line"> <span class="keyword">for</span> (; p && ch[p][d] == q; p = link[p]) ch[p][d] = tmp;</span><br><span class="line"> link[cur] = link[q] = tmp;</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">return</span> lst = cur;</span><br><span class="line"> }</span><br><span class="line">} sam;</span><br><span class="line"></span><br><span class="line">std::vector<<span class="type">int</span>> adj[N];</span><br><span class="line"></span><br><span class="line"><span class="keyword">namespace</span> LCA {</span><br><span class="line"></span><br><span class="line"><span class="type">int</span> dfn[N], clk;</span><br><span class="line"><span class="type">int</span> st[<span class="number">20</span>][N];</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">dfs</span><span class="params">(<span class="type">int</span> u, <span class="type">int</span> frm)</span> </span>{</span><br><span class="line"> st[<span class="number">0</span>][dfn[u] = ++clk] = frm;</span><br><span class="line"> <span class="keyword">for</span> (<span class="keyword">auto</span> v : adj[u]) {</span><br><span class="line"> <span class="keyword">if</span> (v == frm) <span class="keyword">continue</span>;</span><br><span class="line"> <span class="built_in">dfs</span>(v, u);</span><br><span class="line"> } </span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="type">int</span> <span class="title">cmp</span><span class="params">(<span class="type">int</span> u, <span class="type">int</span> v)</span> </span>{ <span class="keyword">return</span> dfn[u] < dfn[v] ? u : v; }</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">init</span><span class="params">()</span> </span>{</span><br><span class="line"> <span class="built_in">dfs</span>(<span class="number">1</span>, <span class="number">0</span>);</span><br><span class="line"> <span class="keyword">for</span> (<span class="type">int</span> i = <span class="number">1</span>; i <= std::__lg(clk); i++) {</span><br><span class="line"> <span class="keyword">for</span> (<span class="type">int</span> j = <span class="number">1</span>; j <= clk - (<span class="number">1</span> << i) + <span class="number">1</span>; j++) {</span><br><span class="line"> st[i][j] = <span class="built_in">cmp</span>(st[i - <span class="number">1</span>][j], st[i - <span class="number">1</span>][j + (<span class="number">1</span> << (i - <span class="number">1</span>))]);</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="type">int</span> <span class="title">queryLCA</span><span class="params">(<span class="type">int</span> u, <span class="type">int</span> v)</span> </span>{</span><br><span class="line"> <span class="keyword">if</span> (u == v) <span class="keyword">return</span> u;</span><br><span class="line"> u = dfn[u], v = dfn[v];</span><br><span class="line"> <span class="keyword">if</span> (u > v) std::<span class="built_in">swap</span>(u, v); </span><br><span class="line"> <span class="type">int</span> d = std::__lg(v - u++);</span><br><span class="line"> <span class="keyword">return</span> <span class="built_in">cmp</span>(st[d][u], st[d][v - (<span class="number">1</span> << d) + <span class="number">1</span>]);</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line">} <span class="comment">// namespace LCA</span></span><br><span class="line"></span><br><span class="line"><span class="keyword">using</span> LCA::queryLCA, LCA::dfn;</span><br><span class="line"></span><br><span class="line">std::vector<<span class="type">int</span>> vadj[N];</span><br><span class="line"><span class="type">int</span> stk[N], top;</span><br><span class="line">i64 f[N], g[N], ans;</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">dp</span><span class="params">(<span class="type">int</span> u)</span> </span>{</span><br><span class="line"> <span class="type">int</span> hav = f[u], len = sam.len[u]; <span class="comment">// hav == 1 means there is a point in u </span></span><br><span class="line"> <span class="keyword">for</span> (<span class="keyword">auto</span> v : vadj[u]) <span class="built_in">dp</span>(v), f[u] += f[v], g[u] += g[v];</span><br><span class="line"> <span class="keyword">for</span> (<span class="keyword">auto</span> v : vadj[u]) ans += f[v] * (g[u] - g[v]) * len;</span><br><span class="line"> ans += hav * g[u] * len;</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">solve</span><span class="params">()</span> </span>{</span><br><span class="line"> std::cin >> n >> m >> (s + <span class="number">1</span>);</span><br><span class="line"> <span class="keyword">for</span> (<span class="type">int</span> i = n; i >= <span class="number">1</span>; i--) pos[i] = sam.<span class="built_in">expand</span>(s[i] - <span class="string">'a'</span>);</span><br><span class="line"></span><br><span class="line"> <span class="keyword">for</span> (<span class="type">int</span> i = <span class="number">2</span>; i <= sam.cnt; i++) adj[sam.link[i]].<span class="built_in">push_back</span>(i);</span><br><span class="line"> LCA::<span class="built_in">init</span>();</span><br><span class="line"></span><br><span class="line"> <span class="keyword">for</span> (<span class="type">int</span> k, l, u; m; m--) {</span><br><span class="line"> std::cin >> k >> l;</span><br><span class="line"> </span><br><span class="line"> std::vector<<span class="type">int</span>> t;</span><br><span class="line"> <span class="keyword">while</span> (k--) t.<span class="built_in">push_back</span>(pos[u = <span class="built_in">read</span>()]), f[pos[u]]++;</span><br><span class="line"> <span class="keyword">while</span> (l--) t.<span class="built_in">push_back</span>(pos[u = <span class="built_in">read</span>()]), g[pos[u]]++;</span><br><span class="line"></span><br><span class="line"> std::<span class="built_in">sort</span>(t.<span class="built_in">begin</span>(), t.<span class="built_in">end</span>(), [&](<span class="type">int</span> lhs, <span class="type">int</span> rhs) {</span><br><span class="line"> <span class="keyword">return</span> dfn[lhs] < dfn[rhs];</span><br><span class="line"> });</span><br><span class="line"> t.<span class="built_in">erase</span>(std::<span class="built_in">unique</span>(t.<span class="built_in">begin</span>(), t.<span class="built_in">end</span>()), t.<span class="built_in">end</span>());</span><br><span class="line"> u32 siz = t.<span class="built_in">size</span>();</span><br><span class="line"> <span class="keyword">for</span> (u32 i = <span class="number">1</span>; i < siz; i++) t.<span class="built_in">push_back</span>(<span class="built_in">queryLCA</span>(t[i - <span class="number">1</span>], t[i]));</span><br><span class="line"> std::<span class="built_in">sort</span>(t.<span class="built_in">begin</span>(), t.<span class="built_in">end</span>(), [&](<span class="type">int</span> lhs, <span class="type">int</span> rhs) {</span><br><span class="line"> <span class="keyword">return</span> dfn[lhs] < dfn[rhs];</span><br><span class="line"> });</span><br><span class="line"> t.<span class="built_in">erase</span>(std::<span class="built_in">unique</span>(t.<span class="built_in">begin</span>(), t.<span class="built_in">end</span>()), t.<span class="built_in">end</span>());</span><br><span class="line"></span><br><span class="line"> stk[top = <span class="number">1</span>] = t[<span class="number">0</span>];</span><br><span class="line"> <span class="keyword">for</span> (u32 i = <span class="number">1</span>; i < t.<span class="built_in">size</span>(); i++) {</span><br><span class="line"> <span class="keyword">while</span> (<span class="built_in">queryLCA</span>(t[i], stk[top]) != stk[top]) top--;</span><br><span class="line"> vadj[stk[top]].<span class="built_in">push_back</span>(t[i]), stk[++top] = t[i];</span><br><span class="line"> }</span><br><span class="line"></span><br><span class="line"> ans = <span class="number">0</span>, <span class="built_in">dp</span>(t[<span class="number">0</span>]);</span><br><span class="line"> std::cout << ans << <span class="string">"\n"</span>;</span><br><span class="line"></span><br><span class="line"> <span class="keyword">for</span> (<span class="keyword">auto</span> i : t) vadj[i].<span class="built_in">clear</span>(), f[i] = g[i] = <span class="number">0</span>;</span><br><span class="line"> }</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">int</span> <span class="title">main</span><span class="params">()</span> </span>{</span><br><span class="line"> std::cin.<span class="built_in">tie</span>(<span class="literal">nullptr</span>)-><span class="built_in">sync_with_stdio</span>(<span class="literal">false</span>);</span><br><span class="line"></span><br><span class="line"> <span class="type">int</span> t = <span class="number">1</span>;</span><br><span class="line"> <span class="comment">// std::cin >> t;</span></span><br><span class="line"> <span class="keyword">while</span> (t--) <span class="built_in">solve</span>();</span><br><span class="line"></span><br><span class="line"> <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">}</span><br></pre></td></tr></table></figure>
</div></article></div><div class="card"><article class="card-content article" role="article"><div class="article-meta is-size-7 is-uppercase level is-mobile"><div class="level-left"><span class="level-item"><time dateTime="2024-01-21T05:03:03.000Z" title="2024/1/21 13:03:03">2024-01-21</time>发表</span><span class="level-item"><time dateTime="2024-01-22T07:00:47.226Z" title="2024/1/22 15:00:47">2024-01-22</time>更新</span><span class="level-item"><a class="link-muted" href="/categories/%E9%A2%98%E8%A7%A3/">题解</a><span> / </span><a class="link-muted" href="/categories/%E9%A2%98%E8%A7%A3/Luogu/">Luogu</a></span><span class="level-item">6 分钟读完 (大约829个字)</span></div></div><p class="title is-3 is-size-4-mobile"><a class="link-muted" href="/2024/01/21/P4022-CTSC2012-%E7%86%9F%E6%82%89%E7%9A%84%E6%96%87%E7%AB%A0/">P4022 [CTSC2012] 熟悉的文章</a></p><div class="content"><p>感觉完全没有黑啊?不知道怎么评出来的。</p>
<p>首先答案显然是可以二分的,我们考虑二分出一个答案之后怎么做。</p>
<p>对于这类问题我们是很容易建出 DP 的模型的。我们设 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.464ex;" xmlns="http://www.w3.org/2000/svg" width="1.848ex" height="2.059ex" role="img" focusable="false" viewBox="0 -705 817 910"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="msub"><g data-mml-node="mi"><path data-c="1D453" d="M118 -162Q120 -162 124 -164T135 -167T147 -168Q160 -168 171 -155T187 -126Q197 -99 221 27T267 267T289 382V385H242Q195 385 192 387Q188 390 188 397L195 425Q197 430 203 430T250 431Q298 431 298 432Q298 434 307 482T319 540Q356 705 465 705Q502 703 526 683T550 630Q550 594 529 578T487 561Q443 561 443 603Q443 622 454 636T478 657L487 662Q471 668 457 668Q445 668 434 658T419 630Q412 601 403 552T387 469T380 433Q380 431 435 431Q480 431 487 430T498 424Q499 420 496 407T491 391Q489 386 482 386T428 385H372L349 263Q301 15 282 -47Q255 -132 212 -173Q175 -205 139 -205Q107 -205 81 -186T55 -132Q55 -95 76 -78T118 -61Q162 -61 162 -103Q162 -122 151 -136T127 -157L118 -162Z"></path></g><g data-mml-node="TeXAtom" transform="translate(523,-150) scale(0.707)" data-mjx-texclass="ORD"><g data-mml-node="mi"><path data-c="1D456" d="M184 600Q184 624 203 642T247 661Q265 661 277 649T290 619Q290 596 270 577T226 557Q211 557 198 567T184 600ZM21 287Q21 295 30 318T54 369T98 420T158 442Q197 442 223 419T250 357Q250 340 236 301T196 196T154 83Q149 61 149 51Q149 26 166 26Q175 26 185 29T208 43T235 78T260 137Q263 149 265 151T282 153Q302 153 302 143Q302 135 293 112T268 61T223 11T161 -11Q129 -11 102 10T74 74Q74 91 79 106T122 220Q160 321 166 341T173 380Q173 404 156 404H154Q124 404 99 371T61 287Q60 286 59 284T58 281T56 279T53 278T49 278T41 278H27Q21 284 21 287Z"></path></g></g></g></g></g></svg></mjx-container> 为 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.025ex;" xmlns="http://www.w3.org/2000/svg" width="0.781ex" height="1.52ex" role="img" focusable="false" viewBox="0 -661 345 672"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="mi"><path data-c="1D456" d="M184 600Q184 624 203 642T247 661Q265 661 277 649T290 619Q290 596 270 577T226 557Q211 557 198 567T184 600ZM21 287Q21 295 30 318T54 369T98 420T158 442Q197 442 223 419T250 357Q250 340 236 301T196 196T154 83Q149 61 149 51Q149 26 166 26Q175 26 185 29T208 43T235 78T260 137Q263 149 265 151T282 153Q302 153 302 143Q302 135 293 112T268 61T223 11T161 -11Q129 -11 102 10T74 74Q74 91 79 106T122 220Q160 321 166 341T173 380Q173 404 156 404H154Q124 404 99 371T61 287Q60 286 59 284T58 281T56 279T53 278T49 278T41 278H27Q21 284 21 287Z"></path></g></g></g></svg></mjx-container> 为当前已经决策到了第 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.025ex;" xmlns="http://www.w3.org/2000/svg" width="0.781ex" height="1.52ex" role="img" focusable="false" viewBox="0 -661 345 672"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="mi"><path data-c="1D456" d="M184 600Q184 624 203 642T247 661Q265 661 277 649T290 619Q290 596 270 577T226 557Q211 557 198 567T184 600ZM21 287Q21 295 30 318T54 369T98 420T158 442Q197 442 223 419T250 357Q250 340 236 301T196 196T154 83Q149 61 149 51Q149 26 166 26Q175 26 185 29T208 43T235 78T260 137Q263 149 265 151T282 153Q302 153 302 143Q302 135 293 112T268 61T223 11T161 -11Q129 -11 102 10T74 74Q74 91 79 106T122 220Q160 321 166 341T173 380Q173 404 156 404H154Q124 404 99 371T61 287Q60 286 59 284T58 281T56 279T53 278T49 278T41 278H27Q21 284 21 287Z"></path></g></g></g></svg></mjx-container> 个字符时所能得到的最大的段的总长。那么这个 DP 的转移就比较显然了。</p>
<p>可以注意到有两种决策。第一种是当前字符不被选入某一段中,那么就有 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.471ex;" xmlns="http://www.w3.org/2000/svg" width="9.261ex" height="2.066ex" role="img" focusable="false" viewBox="0 -705 4093.1 913"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="msub"><g data-mml-node="mi"><path data-c="1D453" d="M118 -162Q120 -162 124 -164T135 -167T147 -168Q160 -168 171 -155T187 -126Q197 -99 221 27T267 267T289 382V385H242Q195 385 192 387Q188 390 188 397L195 425Q197 430 203 430T250 431Q298 431 298 432Q298 434 307 482T319 540Q356 705 465 705Q502 703 526 683T550 630Q550 594 529 578T487 561Q443 561 443 603Q443 622 454 636T478 657L487 662Q471 668 457 668Q445 668 434 658T419 630Q412 601 403 552T387 469T380 433Q380 431 435 431Q480 431 487 430T498 424Q499 420 496 407T491 391Q489 386 482 386T428 385H372L349 263Q301 15 282 -47Q255 -132 212 -173Q175 -205 139 -205Q107 -205 81 -186T55 -132Q55 -95 76 -78T118 -61Q162 -61 162 -103Q162 -122 151 -136T127 -157L118 -162Z"></path></g><g data-mml-node="TeXAtom" transform="translate(523,-150) scale(0.707)" data-mjx-texclass="ORD"><g data-mml-node="mi"><path data-c="1D456" d="M184 600Q184 624 203 642T247 661Q265 661 277 649T290 619Q290 596 270 577T226 557Q211 557 198 567T184 600ZM21 287Q21 295 30 318T54 369T98 420T158 442Q197 442 223 419T250 357Q250 340 236 301T196 196T154 83Q149 61 149 51Q149 26 166 26Q175 26 185 29T208 43T235 78T260 137Q263 149 265 151T282 153Q302 153 302 143Q302 135 293 112T268 61T223 11T161 -11Q129 -11 102 10T74 74Q74 91 79 106T122 220Q160 321 166 341T173 380Q173 404 156 404H154Q124 404 99 371T61 287Q60 286 59 284T58 281T56 279T53 278T49 278T41 278H27Q21 284 21 287Z"></path></g></g></g><g data-mml-node="mo" transform="translate(1094.7,0)"><path data-c="2190" d="M944 261T944 250T929 230H165Q167 228 182 216T211 189T244 152T277 96T303 25Q308 7 308 0Q308 -11 288 -11Q281 -11 278 -11T272 -7T267 2T263 21Q245 94 195 151T73 236Q58 242 55 247Q55 254 59 257T73 264Q121 283 158 314T215 375T247 434T264 480L267 497Q269 503 270 505T275 509T288 511Q308 511 308 500Q308 493 303 475Q293 438 278 406T246 352T215 315T185 287T165 270H929Q944 261 944 250Z"></path></g><g data-mml-node="msub" transform="translate(2372.5,0)"><g data-mml-node="mi"><path data-c="1D453" d="M118 -162Q120 -162 124 -164T135 -167T147 -168Q160 -168 171 -155T187 -126Q197 -99 221 27T267 267T289 382V385H242Q195 385 192 387Q188 390 188 397L195 425Q197 430 203 430T250 431Q298 431 298 432Q298 434 307 482T319 540Q356 705 465 705Q502 703 526 683T550 630Q550 594 529 578T487 561Q443 561 443 603Q443 622 454 636T478 657L487 662Q471 668 457 668Q445 668 434 658T419 630Q412 601 403 552T387 469T380 433Q380 431 435 431Q480 431 487 430T498 424Q499 420 496 407T491 391Q489 386 482 386T428 385H372L349 263Q301 15 282 -47Q255 -132 212 -173Q175 -205 139 -205Q107 -205 81 -186T55 -132Q55 -95 76 -78T118 -61Q162 -61 162 -103Q162 -122 151 -136T127 -157L118 -162Z"></path></g><g data-mml-node="TeXAtom" transform="translate(523,-150) scale(0.707)" data-mjx-texclass="ORD"><g data-mml-node="mi"><path data-c="1D456" d="M184 600Q184 624 203 642T247 661Q265 661 277 649T290 619Q290 596 270 577T226 557Q211 557 198 567T184 600ZM21 287Q21 295 30 318T54 369T98 420T158 442Q197 442 223 419T250 357Q250 340 236 301T196 196T154 83Q149 61 149 51Q149 26 166 26Q175 26 185 29T208 43T235 78T260 137Q263 149 265 151T282 153Q302 153 302 143Q302 135 293 112T268 61T223 11T161 -11Q129 -11 102 10T74 74Q74 91 79 106T122 220Q160 321 166 341T173 380Q173 404 156 404H154Q124 404 99 371T61 287Q60 286 59 284T58 281T56 279T53 278T49 278T41 278H27Q21 284 21 287Z"></path></g><g data-mml-node="mo" transform="translate(345,0)"><path data-c="2212" d="M84 237T84 250T98 270H679Q694 262 694 250T679 230H98Q84 237 84 250Z"></path></g><g data-mml-node="mn" transform="translate(1123,0)"><path data-c="31" d="M213 578L200 573Q186 568 160 563T102 556H83V602H102Q149 604 189 617T245 641T273 663Q275 666 285 666Q294 666 302 660V361L303 61Q310 54 315 52T339 48T401 46H427V0H416Q395 3 257 3Q121 3 100 0H88V46H114Q136 46 152 46T177 47T193 50T201 52T207 57T213 61V578Z"></path></g></g></g></g></g></svg></mjx-container>。另一种是将当前划入某一段中,枚举这一段的开头 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.462ex;" xmlns="http://www.w3.org/2000/svg" width="0.932ex" height="1.957ex" role="img" focusable="false" viewBox="0 -661 412 865"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="mi"><path data-c="1D457" d="M297 596Q297 627 318 644T361 661Q378 661 389 651T403 623Q403 595 384 576T340 557Q322 557 310 567T297 596ZM288 376Q288 405 262 405Q240 405 220 393T185 362T161 325T144 293L137 279Q135 278 121 278H107Q101 284 101 286T105 299Q126 348 164 391T252 441Q253 441 260 441T272 442Q296 441 316 432Q341 418 354 401T367 348V332L318 133Q267 -67 264 -75Q246 -125 194 -164T75 -204Q25 -204 7 -183T-12 -137Q-12 -110 7 -91T53 -71Q70 -71 82 -81T95 -112Q95 -148 63 -167Q69 -168 77 -168Q111 -168 139 -140T182 -74L193 -32Q204 11 219 72T251 197T278 308T289 365Q289 372 288 376Z"></path></g></g></g></svg></mjx-container>,则有 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.666ex;" xmlns="http://www.w3.org/2000/svg" width="27.737ex" height="2.363ex" role="img" focusable="false" viewBox="0 -750 12259.9 1044.2"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="msub"><g data-mml-node="mi"><path data-c="1D453" d="M118 -162Q120 -162 124 -164T135 -167T147 -168Q160 -168 171 -155T187 -126Q197 -99 221 27T267 267T289 382V385H242Q195 385 192 387Q188 390 188 397L195 425Q197 430 203 430T250 431Q298 431 298 432Q298 434 307 482T319 540Q356 705 465 705Q502 703 526 683T550 630Q550 594 529 578T487 561Q443 561 443 603Q443 622 454 636T478 657L487 662Q471 668 457 668Q445 668 434 658T419 630Q412 601 403 552T387 469T380 433Q380 431 435 431Q480 431 487 430T498 424Q499 420 496 407T491 391Q489 386 482 386T428 385H372L349 263Q301 15 282 -47Q255 -132 212 -173Q175 -205 139 -205Q107 -205 81 -186T55 -132Q55 -95 76 -78T118 -61Q162 -61 162 -103Q162 -122 151 -136T127 -157L118 -162Z"></path></g><g data-mml-node="TeXAtom" transform="translate(523,-150) scale(0.707)" data-mjx-texclass="ORD"><g data-mml-node="mi"><path data-c="1D456" d="M184 600Q184 624 203 642T247 661Q265 661 277 649T290 619Q290 596 270 577T226 557Q211 557 198 567T184 600ZM21 287Q21 295 30 318T54 369T98 420T158 442Q197 442 223 419T250 357Q250 340 236 301T196 196T154 83Q149 61 149 51Q149 26 166 26Q175 26 185 29T208 43T235 78T260 137Q263 149 265 151T282 153Q302 153 302 143Q302 135 293 112T268 61T223 11T161 -11Q129 -11 102 10T74 74Q74 91 79 106T122 220Q160 321 166 341T173 380Q173 404 156 404H154Q124 404 99 371T61 287Q60 286 59 284T58 281T56 279T53 278T49 278T41 278H27Q21 284 21 287Z"></path></g></g></g><g data-mml-node="mo" transform="translate(1094.7,0)"><path data-c="3D" d="M56 347Q56 360 70 367H707Q722 359 722 347Q722 336 708 328L390 327H72Q56 332 56 347ZM56 153Q56 168 72 173H708Q722 163 722 153Q722 140 707 133H70Q56 140 56 153Z"></path></g><g data-mml-node="mo" transform="translate(2150.5,0)"><path data-c="6D" d="M41 46H55Q94 46 102 60V68Q102 77 102 91T102 122T103 161T103 203Q103 234 103 269T102 328V351Q99 370 88 376T43 385H25V408Q25 431 27 431L37 432Q47 433 65 434T102 436Q119 437 138 438T167 441T178 442H181V402Q181 364 182 364T187 369T199 384T218 402T247 421T285 437Q305 442 336 442Q351 442 364 440T387 434T406 426T421 417T432 406T441 395T448 384T452 374T455 366L457 361L460 365Q463 369 466 373T475 384T488 397T503 410T523 422T546 432T572 439T603 442Q729 442 740 329Q741 322 741 190V104Q741 66 743 59T754 49Q775 46 803 46H819V0H811L788 1Q764 2 737 2T699 3Q596 3 587 0H579V46H595Q656 46 656 62Q657 64 657 200Q656 335 655 343Q649 371 635 385T611 402T585 404Q540 404 506 370Q479 343 472 315T464 232V168V108Q464 78 465 68T468 55T477 49Q498 46 526 46H542V0H534L510 1Q487 2 460 2T422 3Q319 3 310 0H302V46H318Q379 46 379 62Q380 64 380 200Q379 335 378 343Q372 371 358 385T334 402T308 404Q263 404 229 370Q202 343 195 315T187 232V168V108Q187 78 188 68T191 55T200 49Q221 46 249 46H265V0H257L234 1Q210 2 183 2T145 3Q42 3 33 0H25V46H41Z"></path><path data-c="61" d="M137 305T115 305T78 320T63 359Q63 394 97 421T218 448Q291 448 336 416T396 340Q401 326 401 309T402 194V124Q402 76 407 58T428 40Q443 40 448 56T453 109V145H493V106Q492 66 490 59Q481 29 455 12T400 -6T353 12T329 54V58L327 55Q325 52 322 49T314 40T302 29T287 17T269 6T247 -2T221 -8T190 -11Q130 -11 82 20T34 107Q34 128 41 147T68 188T116 225T194 253T304 268H318V290Q318 324 312 340Q290 411 215 411Q197 411 181 410T156 406T148 403Q170 388 170 359Q170 334 154 320ZM126 106Q126 75 150 51T209 26Q247 26 276 49T315 109Q317 116 318 175Q318 233 317 233Q309 233 296 232T251 223T193 203T147 166T126 106Z" transform="translate(833,0)"></path><path data-c="78" d="M201 0Q189 3 102 3Q26 3 17 0H11V46H25Q48 47 67 52T96 61T121 78T139 96T160 122T180 150L226 210L168 288Q159 301 149 315T133 336T122 351T113 363T107 370T100 376T94 379T88 381T80 383Q74 383 44 385H16V431H23Q59 429 126 429Q219 429 229 431H237V385Q201 381 201 369Q201 367 211 353T239 315T268 274L272 270L297 304Q329 345 329 358Q329 364 327 369T322 376T317 380T310 384L307 385H302V431H309Q324 428 408 428Q487 428 493 431H499V385H492Q443 385 411 368Q394 360 377 341T312 257L296 236L358 151Q424 61 429 57T446 50Q464 46 499 46H516V0H510H502Q494 1 482 1T457 2T432 2T414 3Q403 3 377 3T327 1L304 0H295V46H298Q309 46 320 51T331 63Q331 65 291 120L250 175Q249 174 219 133T185 88Q181 83 181 74Q181 63 188 55T206 46Q208 46 208 23V0H201Z" transform="translate(1333,0)"></path></g><g data-mml-node="mo" transform="translate(4011.5,0)"><path data-c="28" d="M94 250Q94 319 104 381T127 488T164 576T202 643T244 695T277 729T302 750H315H319Q333 750 333 741Q333 738 316 720T275 667T226 581T184 443T167 250T184 58T225 -81T274 -167T316 -220T333 -241Q333 -250 318 -250H315H302L274 -226Q180 -141 137 -14T94 250Z"></path></g><g data-mml-node="msub" transform="translate(4400.5,0)"><g data-mml-node="mi"><path data-c="1D453" d="M118 -162Q120 -162 124 -164T135 -167T147 -168Q160 -168 171 -155T187 -126Q197 -99 221 27T267 267T289 382V385H242Q195 385 192 387Q188 390 188 397L195 425Q197 430 203 430T250 431Q298 431 298 432Q298 434 307 482T319 540Q356 705 465 705Q502 703 526 683T550 630Q550 594 529 578T487 561Q443 561 443 603Q443 622 454 636T478 657L487 662Q471 668 457 668Q445 668 434 658T419 630Q412 601 403 552T387 469T380 433Q380 431 435 431Q480 431 487 430T498 424Q499 420 496 407T491 391Q489 386 482 386T428 385H372L349 263Q301 15 282 -47Q255 -132 212 -173Q175 -205 139 -205Q107 -205 81 -186T55 -132Q55 -95 76 -78T118 -61Q162 -61 162 -103Q162 -122 151 -136T127 -157L118 -162Z"></path></g><g data-mml-node="TeXAtom" transform="translate(523,-150) scale(0.707)" data-mjx-texclass="ORD"><g data-mml-node="mi"><path data-c="1D457" d="M297 596Q297 627 318 644T361 661Q378 661 389 651T403 623Q403 595 384 576T340 557Q322 557 310 567T297 596ZM288 376Q288 405 262 405Q240 405 220 393T185 362T161 325T144 293L137 279Q135 278 121 278H107Q101 284 101 286T105 299Q126 348 164 391T252 441Q253 441 260 441T272 442Q296 441 316 432Q341 418 354 401T367 348V332L318 133Q267 -67 264 -75Q246 -125 194 -164T75 -204Q25 -204 7 -183T-12 -137Q-12 -110 7 -91T53 -71Q70 -71 82 -81T95 -112Q95 -148 63 -167Q69 -168 77 -168Q111 -168 139 -140T182 -74L193 -32Q204 11 219 72T251 197T278 308T289 365Q289 372 288 376Z"></path></g><g data-mml-node="mo" transform="translate(412,0)"><path data-c="2212" d="M84 237T84 250T98 270H679Q694 262 694 250T679 230H98Q84 237 84 250Z"></path></g><g data-mml-node="mn" transform="translate(1190,0)"><path data-c="31" d="M213 578L200 573Q186 568 160 563T102 556H83V602H102Q149 604 189 617T245 641T273 663Q275 666 285 666Q294 666 302 660V361L303 61Q310 54 315 52T339 48T401 46H427V0H416Q395 3 257 3Q121 3 100 0H88V46H114Q136 46 152 46T177 47T193 50T201 52T207 57T213 61V578Z"></path></g></g></g><g data-mml-node="mo" transform="translate(6390.7,0)"><path data-c="2B" d="M56 237T56 250T70 270H369V420L370 570Q380 583 389 583Q402 583 409 568V270H707Q722 262 722 250T707 230H409V-68Q401 -82 391 -82H389H387Q375 -82 369 -68V230H70Q56 237 56 250Z"></path></g><g data-mml-node="mo" transform="translate(7391,0)"><path data-c="28" d="M94 250Q94 319 104 381T127 488T164 576T202 643T244 695T277 729T302 750H315H319Q333 750 333 741Q333 738 316 720T275 667T226 581T184 443T167 250T184 58T225 -81T274 -167T316 -220T333 -241Q333 -250 318 -250H315H302L274 -226Q180 -141 137 -14T94 250Z"></path></g><g data-mml-node="mi" transform="translate(7780,0)"><path data-c="1D456" d="M184 600Q184 624 203 642T247 661Q265 661 277 649T290 619Q290 596 270 577T226 557Q211 557 198 567T184 600ZM21 287Q21 295 30 318T54 369T98 420T158 442Q197 442 223 419T250 357Q250 340 236 301T196 196T154 83Q149 61 149 51Q149 26 166 26Q175 26 185 29T208 43T235 78T260 137Q263 149 265 151T282 153Q302 153 302 143Q302 135 293 112T268 61T223 11T161 -11Q129 -11 102 10T74 74Q74 91 79 106T122 220Q160 321 166 341T173 380Q173 404 156 404H154Q124 404 99 371T61 287Q60 286 59 284T58 281T56 279T53 278T49 278T41 278H27Q21 284 21 287Z"></path></g><g data-mml-node="mo" transform="translate(8347.2,0)"><path data-c="2212" d="M84 237T84 250T98 270H679Q694 262 694 250T679 230H98Q84 237 84 250Z"></path></g><g data-mml-node="mi" transform="translate(9347.4,0)"><path data-c="1D457" d="M297 596Q297 627 318 644T361 661Q378 661 389 651T403 623Q403 595 384 576T340 557Q322 557 310 567T297 596ZM288 376Q288 405 262 405Q240 405 220 393T185 362T161 325T144 293L137 279Q135 278 121 278H107Q101 284 101 286T105 299Q126 348 164 391T252 441Q253 441 260 441T272 442Q296 441 316 432Q341 418 354 401T367 348V332L318 133Q267 -67 264 -75Q246 -125 194 -164T75 -204Q25 -204 7 -183T-12 -137Q-12 -110 7 -91T53 -71Q70 -71 82 -81T95 -112Q95 -148 63 -167Q69 -168 77 -168Q111 -168 139 -140T182 -74L193 -32Q204 11 219 72T251 197T278 308T289 365Q289 372 288 376Z"></path></g><g data-mml-node="mo" transform="translate(9981.6,0)"><path data-c="2B" d="M56 237T56 250T70 270H369V420L370 570Q380 583 389 583Q402 583 409 568V270H707Q722 262 722 250T707 230H409V-68Q401 -82 391 -82H389H387Q375 -82 369 -68V230H70Q56 237 56 250Z"></path></g><g data-mml-node="mn" transform="translate(10981.9,0)"><path data-c="31" d="M213 578L200 573Q186 568 160 563T102 556H83V602H102Q149 604 189 617T245 641T273 663Q275 666 285 666Q294 666 302 660V361L303 61Q310 54 315 52T339 48T401 46H427V0H416Q395 3 257 3Q121 3 100 0H88V46H114Q136 46 152 46T177 47T193 50T201 52T207 57T213 61V578Z"></path></g><g data-mml-node="mo" transform="translate(11481.9,0)"><path data-c="29" d="M60 749L64 750Q69 750 74 750H86L114 726Q208 641 251 514T294 250Q294 182 284 119T261 12T224 -76T186 -143T145 -194T113 -227T90 -246Q87 -249 86 -250H74Q66 -250 63 -250T58 -247T55 -238Q56 -237 66 -225Q221 -64 221 250T66 725Q56 737 55 738Q55 746 60 749Z"></path></g><g data-mml-node="mo" transform="translate(11870.9,0)"><path data-c="29" d="M60 749L64 750Q69 750 74 750H86L114 726Q208 641 251 514T294 250Q294 182 284 119T261 12T224 -76T186 -143T145 -194T113 -227T90 -246Q87 -249 86 -250H74Q66 -250 63 -250T58 -247T55 -238Q56 -237 66 -225Q221 -64 221 250T66 725Q56 737 55 738Q55 746 60 749Z"></path></g></g></g></svg></mjx-container>,当然 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.462ex;" xmlns="http://www.w3.org/2000/svg" width="0.932ex" height="1.957ex" role="img" focusable="false" viewBox="0 -661 412 865"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="mi"><path data-c="1D457" d="M297 596Q297 627 318 644T361 661Q378 661 389 651T403 623Q403 595 384 576T340 557Q322 557 310 567T297 596ZM288 376Q288 405 262 405Q240 405 220 393T185 362T161 325T144 293L137 279Q135 278 121 278H107Q101 284 101 286T105 299Q126 348 164 391T252 441Q253 441 260 441T272 442Q296 441 316 432Q341 418 354 401T367 348V332L318 133Q267 -67 264 -75Q246 -125 194 -164T75 -204Q25 -204 7 -183T-12 -137Q-12 -110 7 -91T53 -71Q70 -71 82 -81T95 -112Q95 -148 63 -167Q69 -168 77 -168Q111 -168 139 -140T182 -74L193 -32Q204 11 219 72T251 197T278 308T289 365Q289 372 288 376Z"></path></g></g></g></svg></mjx-container> 是有选取范围的,设当前二分的答案为 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.025ex;" xmlns="http://www.w3.org/2000/svg" width="1.294ex" height="1.025ex" role="img" focusable="false" viewBox="0 -442 572 453"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="mi"><path data-c="1D462" d="M21 287Q21 295 30 318T55 370T99 420T158 442Q204 442 227 417T250 358Q250 340 216 246T182 105Q182 62 196 45T238 27T291 44T328 78L339 95Q341 99 377 247Q407 367 413 387T427 416Q444 431 463 431Q480 431 488 421T496 402L420 84Q419 79 419 68Q419 43 426 35T447 26Q469 29 482 57T512 145Q514 153 532 153Q551 153 551 144Q550 139 549 130T540 98T523 55T498 17T462 -8Q454 -10 438 -10Q372 -10 347 46Q345 45 336 36T318 21T296 6T267 -6T233 -11Q189 -11 155 7Q103 38 103 113Q103 170 138 262T173 379Q173 380 173 381Q173 390 173 393T169 400T158 404H154Q131 404 112 385T82 344T65 302T57 280Q55 278 41 278H27Q21 284 21 287Z"></path></g></g></g></svg></mjx-container>,且 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.025ex;" xmlns="http://www.w3.org/2000/svg" width="0.781ex" height="1.52ex" role="img" focusable="false" viewBox="0 -661 345 672"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="mi"><path data-c="1D456" d="M184 600Q184 624 203 642T247 661Q265 661 277 649T290 619Q290 596 270 577T226 557Q211 557 198 567T184 600ZM21 287Q21 295 30 318T54 369T98 420T158 442Q197 442 223 419T250 357Q250 340 236 301T196 196T154 83Q149 61 149 51Q149 26 166 26Q175 26 185 29T208 43T235 78T260 137Q263 149 265 151T282 153Q302 153 302 143Q302 135 293 112T268 61T223 11T161 -11Q129 -11 102 10T74 74Q74 91 79 106T122 220Q160 321 166 341T173 380Q173 404 156 404H154Q124 404 99 371T61 287Q60 286 59 284T58 281T56 279T53 278T49 278T41 278H27Q21 284 21 287Z"></path></g></g></g></svg></mjx-container> 在原串中最多往前匹配 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.025ex;" xmlns="http://www.w3.org/2000/svg" width="3.086ex" height="1.595ex" role="img" focusable="false" viewBox="0 -694 1364 705"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="mi"><path data-c="1D459" d="M117 59Q117 26 142 26Q179 26 205 131Q211 151 215 152Q217 153 225 153H229Q238 153 241 153T246 151T248 144Q247 138 245 128T234 90T214 43T183 6T137 -11Q101 -11 70 11T38 85Q38 97 39 102L104 360Q167 615 167 623Q167 626 166 628T162 632T157 634T149 635T141 636T132 637T122 637Q112 637 109 637T101 638T95 641T94 647Q94 649 96 661Q101 680 107 682T179 688Q194 689 213 690T243 693T254 694Q266 694 266 686Q266 675 193 386T118 83Q118 81 118 75T117 65V59Z"></path></g><g data-mml-node="mi" transform="translate(298,0)"><path data-c="1D452" d="M39 168Q39 225 58 272T107 350T174 402T244 433T307 442H310Q355 442 388 420T421 355Q421 265 310 237Q261 224 176 223Q139 223 138 221Q138 219 132 186T125 128Q125 81 146 54T209 26T302 45T394 111Q403 121 406 121Q410 121 419 112T429 98T420 82T390 55T344 24T281 -1T205 -11Q126 -11 83 42T39 168ZM373 353Q367 405 305 405Q272 405 244 391T199 357T170 316T154 280T149 261Q149 260 169 260Q282 260 327 284T373 353Z"></path></g><g data-mml-node="mi" transform="translate(764,0)"><path data-c="1D45B" d="M21 287Q22 293 24 303T36 341T56 388T89 425T135 442Q171 442 195 424T225 390T231 369Q231 367 232 367L243 378Q304 442 382 442Q436 442 469 415T503 336T465 179T427 52Q427 26 444 26Q450 26 453 27Q482 32 505 65T540 145Q542 153 560 153Q580 153 580 145Q580 144 576 130Q568 101 554 73T508 17T439 -10Q392 -10 371 17T350 73Q350 92 386 193T423 345Q423 404 379 404H374Q288 404 229 303L222 291L189 157Q156 26 151 16Q138 -11 108 -11Q95 -11 87 -5T76 7T74 17Q74 30 112 180T152 343Q153 348 153 366Q153 405 129 405Q91 405 66 305Q60 285 60 284Q58 278 41 278H27Q21 284 21 287Z"></path></g></g></g></svg></mjx-container> 位,则有 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.462ex;" xmlns="http://www.w3.org/2000/svg" width="18.79ex" height="2.032ex" role="img" focusable="false" viewBox="0 -694 8305 898"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="mi"><path data-c="1D462" d="M21 287Q21 295 30 318T55 370T99 420T158 442Q204 442 227 417T250 358Q250 340 216 246T182 105Q182 62 196 45T238 27T291 44T328 78L339 95Q341 99 377 247Q407 367 413 387T427 416Q444 431 463 431Q480 431 488 421T496 402L420 84Q419 79 419 68Q419 43 426 35T447 26Q469 29 482 57T512 145Q514 153 532 153Q551 153 551 144Q550 139 549 130T540 98T523 55T498 17T462 -8Q454 -10 438 -10Q372 -10 347 46Q345 45 336 36T318 21T296 6T267 -6T233 -11Q189 -11 155 7Q103 38 103 113Q103 170 138 262T173 379Q173 380 173 381Q173 390 173 393T169 400T158 404H154Q131 404 112 385T82 344T65 302T57 280Q55 278 41 278H27Q21 284 21 287Z"></path></g><g data-mml-node="mo" transform="translate(849.8,0)"><path data-c="2264" d="M674 636Q682 636 688 630T694 615T687 601Q686 600 417 472L151 346L399 228Q687 92 691 87Q694 81 694 76Q694 58 676 56H670L382 192Q92 329 90 331Q83 336 83 348Q84 359 96 365Q104 369 382 500T665 634Q669 636 674 636ZM84 -118Q84 -108 99 -98H678Q694 -104 694 -118Q694 -130 679 -138H98Q84 -131 84 -118Z"></path></g><g data-mml-node="mi" transform="translate(1905.6,0)"><path data-c="1D456" d="M184 600Q184 624 203 642T247 661Q265 661 277 649T290 619Q290 596 270 577T226 557Q211 557 198 567T184 600ZM21 287Q21 295 30 318T54 369T98 420T158 442Q197 442 223 419T250 357Q250 340 236 301T196 196T154 83Q149 61 149 51Q149 26 166 26Q175 26 185 29T208 43T235 78T260 137Q263 149 265 151T282 153Q302 153 302 143Q302 135 293 112T268 61T223 11T161 -11Q129 -11 102 10T74 74Q74 91 79 106T122 220Q160 321 166 341T173 380Q173 404 156 404H154Q124 404 99 371T61 287Q60 286 59 284T58 281T56 279T53 278T49 278T41 278H27Q21 284 21 287Z"></path></g><g data-mml-node="mo" transform="translate(2472.8,0)"><path data-c="2212" d="M84 237T84 250T98 270H679Q694 262 694 250T679 230H98Q84 237 84 250Z"></path></g><g data-mml-node="mi" transform="translate(3473,0)"><path data-c="1D457" d="M297 596Q297 627 318 644T361 661Q378 661 389 651T403 623Q403 595 384 576T340 557Q322 557 310 567T297 596ZM288 376Q288 405 262 405Q240 405 220 393T185 362T161 325T144 293L137 279Q135 278 121 278H107Q101 284 101 286T105 299Q126 348 164 391T252 441Q253 441 260 441T272 442Q296 441 316 432Q341 418 354 401T367 348V332L318 133Q267 -67 264 -75Q246 -125 194 -164T75 -204Q25 -204 7 -183T-12 -137Q-12 -110 7 -91T53 -71Q70 -71 82 -81T95 -112Q95 -148 63 -167Q69 -168 77 -168Q111 -168 139 -140T182 -74L193 -32Q204 11 219 72T251 197T278 308T289 365Q289 372 288 376Z"></path></g><g data-mml-node="mo" transform="translate(4107.2,0)"><path data-c="2B" d="M56 237T56 250T70 270H369V420L370 570Q380 583 389 583Q402 583 409 568V270H707Q722 262 722 250T707 230H409V-68Q401 -82 391 -82H389H387Q375 -82 369 -68V230H70Q56 237 56 250Z"></path></g><g data-mml-node="mn" transform="translate(5107.4,0)"><path data-c="31" d="M213 578L200 573Q186 568 160 563T102 556H83V602H102Q149 604 189 617T245 641T273 663Q275 666 285 666Q294 666 302 660V361L303 61Q310 54 315 52T339 48T401 46H427V0H416Q395 3 257 3Q121 3 100 0H88V46H114Q136 46 152 46T177 47T193 50T201 52T207 57T213 61V578Z"></path></g><g data-mml-node="mo" transform="translate(5885.2,0)"><path data-c="2264" d="M674 636Q682 636 688 630T694 615T687 601Q686 600 417 472L151 346L399 228Q687 92 691 87Q694 81 694 76Q694 58 676 56H670L382 192Q92 329 90 331Q83 336 83 348Q84 359 96 365Q104 369 382 500T665 634Q669 636 674 636ZM84 -118Q84 -108 99 -98H678Q694 -104 694 -118Q694 -130 679 -138H98Q84 -131 84 -118Z"></path></g><g data-mml-node="mi" transform="translate(6941,0)"><path data-c="1D459" d="M117 59Q117 26 142 26Q179 26 205 131Q211 151 215 152Q217 153 225 153H229Q238 153 241 153T246 151T248 144Q247 138 245 128T234 90T214 43T183 6T137 -11Q101 -11 70 11T38 85Q38 97 39 102L104 360Q167 615 167 623Q167 626 166 628T162 632T157 634T149 635T141 636T132 637T122 637Q112 637 109 637T101 638T95 641T94 647Q94 649 96 661Q101 680 107 682T179 688Q194 689 213 690T243 693T254 694Q266 694 266 686Q266 675 193 386T118 83Q118 81 118 75T117 65V59Z"></path></g><g data-mml-node="mi" transform="translate(7239,0)"><path data-c="1D452" d="M39 168Q39 225 58 272T107 350T174 402T244 433T307 442H310Q355 442 388 420T421 355Q421 265 310 237Q261 224 176 223Q139 223 138 221Q138 219 132 186T125 128Q125 81 146 54T209 26T302 45T394 111Q403 121 406 121Q410 121 419 112T429 98T420 82T390 55T344 24T281 -1T205 -11Q126 -11 83 42T39 168ZM373 353Q367 405 305 405Q272 405 244 391T199 357T170 316T154 280T149 261Q149 260 169 260Q282 260 327 284T373 353Z"></path></g><g data-mml-node="mi" transform="translate(7705,0)"><path data-c="1D45B" d="M21 287Q22 293 24 303T36 341T56 388T89 425T135 442Q171 442 195 424T225 390T231 369Q231 367 232 367L243 378Q304 442 382 442Q436 442 469 415T503 336T465 179T427 52Q427 26 444 26Q450 26 453 27Q482 32 505 65T540 145Q542 153 560 153Q580 153 580 145Q580 144 576 130Q568 101 554 73T508 17T439 -10Q392 -10 371 17T350 73Q350 92 386 193T423 345Q423 404 379 404H374Q288 404 229 303L222 291L189 157Q156 26 151 16Q138 -11 108 -11Q95 -11 87 -5T76 7T74 17Q74 30 112 180T152 343Q153 348 153 366Q153 405 129 405Q91 405 66 305Q60 285 60 284Q58 278 41 278H27Q21 284 21 287Z"></path></g></g></g></svg></mjx-container>。这样就可以容易的做到 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.566ex;" xmlns="http://www.w3.org/2000/svg" width="10.909ex" height="2.452ex" role="img" focusable="false" viewBox="0 -833.9 4821.9 1083.9"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="TeXAtom" data-mjx-texclass="ORD"><g data-mml-node="mi"><path data-c="4F" d="M308 428Q289 428 289 438Q289 457 318 508T378 593Q417 638 475 671T599 705Q688 705 732 643T777 483Q777 380 733 285T620 123T464 18T293 -22Q188 -22 123 51T58 245Q58 327 87 403T159 533T249 626T333 685T388 705Q404 705 404 693Q404 674 363 649Q333 632 304 606T239 537T181 429T158 290Q158 179 214 114T364 48Q489 48 583 165T677 438Q677 473 670 505T648 568T601 617T528 636Q518 636 513 635Q486 629 460 600T419 544T392 490Q383 470 372 459Q341 430 308 428Z"></path></g></g><g data-mml-node="mo" transform="translate(796,0)"><path data-c="28" d="M94 250Q94 319 104 381T127 488T164 576T202 643T244 695T277 729T302 750H315H319Q333 750 333 741Q333 738 316 720T275 667T226 581T184 443T167 250T184 58T225 -81T274 -167T316 -220T333 -241Q333 -250 318 -250H315H302L274 -226Q180 -141 137 -14T94 250Z"></path></g><g data-mml-node="msup" transform="translate(1185,0)"><g data-mml-node="mi"><path data-c="1D45B" d="M21 287Q22 293 24 303T36 341T56 388T89 425T135 442Q171 442 195 424T225 390T231 369Q231 367 232 367L243 378Q304 442 382 442Q436 442 469 415T503 336T465 179T427 52Q427 26 444 26Q450 26 453 27Q482 32 505 65T540 145Q542 153 560 153Q580 153 580 145Q580 144 576 130Q568 101 554 73T508 17T439 -10Q392 -10 371 17T350 73Q350 92 386 193T423 345Q423 404 379 404H374Q288 404 229 303L222 291L189 157Q156 26 151 16Q138 -11 108 -11Q95 -11 87 -5T76 7T74 17Q74 30 112 180T152 343Q153 348 153 366Q153 405 129 405Q91 405 66 305Q60 285 60 284Q58 278 41 278H27Q21 284 21 287Z"></path></g><g data-mml-node="mn" transform="translate(633,363) scale(0.707)"><path data-c="32" d="M109 429Q82 429 66 447T50 491Q50 562 103 614T235 666Q326 666 387 610T449 465Q449 422 429 383T381 315T301 241Q265 210 201 149L142 93L218 92Q375 92 385 97Q392 99 409 186V189H449V186Q448 183 436 95T421 3V0H50V19V31Q50 38 56 46T86 81Q115 113 136 137Q145 147 170 174T204 211T233 244T261 278T284 308T305 340T320 369T333 401T340 431T343 464Q343 527 309 573T212 619Q179 619 154 602T119 569T109 550Q109 549 114 549Q132 549 151 535T170 489Q170 464 154 447T109 429Z"></path></g></g><g data-mml-node="mi" transform="translate(2388.2,0)"><path data-c="6C" d="M42 46H56Q95 46 103 60V68Q103 77 103 91T103 124T104 167T104 217T104 272T104 329Q104 366 104 407T104 482T104 542T103 586T103 603Q100 622 89 628T44 637H26V660Q26 683 28 683L38 684Q48 685 67 686T104 688Q121 689 141 690T171 693T182 694H185V379Q185 62 186 60Q190 52 198 49Q219 46 247 46H263V0H255L232 1Q209 2 183 2T145 3T107 3T57 1L34 0H26V46H42Z"></path><path data-c="6F" d="M28 214Q28 309 93 378T250 448Q340 448 405 380T471 215Q471 120 407 55T250 -10Q153 -10 91 57T28 214ZM250 30Q372 30 372 193V225V250Q372 272 371 288T364 326T348 362T317 390T268 410Q263 411 252 411Q222 411 195 399Q152 377 139 338T126 246V226Q126 130 145 91Q177 30 250 30Z" transform="translate(278,0)"></path><path data-c="67" d="M329 409Q373 453 429 453Q459 453 472 434T485 396Q485 382 476 371T449 360Q416 360 412 390Q410 404 415 411Q415 412 416 414V415Q388 412 363 393Q355 388 355 386Q355 385 359 381T368 369T379 351T388 325T392 292Q392 230 343 187T222 143Q172 143 123 171Q112 153 112 133Q112 98 138 81Q147 75 155 75T227 73Q311 72 335 67Q396 58 431 26Q470 -13 470 -72Q470 -139 392 -175Q332 -206 250 -206Q167 -206 107 -175Q29 -140 29 -75Q29 -39 50 -15T92 18L103 24Q67 55 67 108Q67 155 96 193Q52 237 52 292Q52 355 102 398T223 442Q274 442 318 416L329 409ZM299 343Q294 371 273 387T221 404Q192 404 171 388T145 343Q142 326 142 292Q142 248 149 227T179 192Q196 182 222 182Q244 182 260 189T283 207T294 227T299 242Q302 258 302 292T299 343ZM403 -75Q403 -50 389 -34T348 -11T299 -2T245 0H218Q151 0 138 -6Q118 -15 107 -34T95 -74Q95 -84 101 -97T122 -127T170 -155T250 -167Q319 -167 361 -139T403 -75Z" transform="translate(778,0)"></path></g><g data-mml-node="mo" transform="translate(3666.2,0)"><path data-c="2061" d=""></path></g><g data-mml-node="mi" transform="translate(3832.9,0)"><path data-c="1D45B" d="M21 287Q22 293 24 303T36 341T56 388T89 425T135 442Q171 442 195 424T225 390T231 369Q231 367 232 367L243 378Q304 442 382 442Q436 442 469 415T503 336T465 179T427 52Q427 26 444 26Q450 26 453 27Q482 32 505 65T540 145Q542 153 560 153Q580 153 580 145Q580 144 576 130Q568 101 554 73T508 17T439 -10Q392 -10 371 17T350 73Q350 92 386 193T423 345Q423 404 379 404H374Q288 404 229 303L222 291L189 157Q156 26 151 16Q138 -11 108 -11Q95 -11 87 -5T76 7T74 17Q74 30 112 180T152 343Q153 348 153 366Q153 405 129 405Q91 405 66 305Q60 285 60 284Q58 278 41 278H27Q21 284 21 287Z"></path></g><g data-mml-node="mo" transform="translate(4432.9,0)"><path data-c="29" d="M60 749L64 750Q69 750 74 750H86L114 726Q208 641 251 514T294 250Q294 182 284 119T261 12T224 -76T186 -143T145 -194T113 -227T90 -246Q87 -249 86 -250H74Q66 -250 63 -250T58 -247T55 -238Q56 -237 66 -225Q221 -64 221 250T66 725Q56 737 55 738Q55 746 60 749Z"></path></g></g></g></svg></mjx-container> 的时间复杂度了,其中 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.025ex;" xmlns="http://www.w3.org/2000/svg" width="1.357ex" height="1.025ex" role="img" focusable="false" viewBox="0 -442 600 453"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="mi"><path data-c="1D45B" d="M21 287Q22 293 24 303T36 341T56 388T89 425T135 442Q171 442 195 424T225 390T231 369Q231 367 232 367L243 378Q304 442 382 442Q436 442 469 415T503 336T465 179T427 52Q427 26 444 26Q450 26 453 27Q482 32 505 65T540 145Q542 153 560 153Q580 153 580 145Q580 144 576 130Q568 101 554 73T508 17T439 -10Q392 -10 371 17T350 73Q350 92 386 193T423 345Q423 404 379 404H374Q288 404 229 303L222 291L189 157Q156 26 151 16Q138 -11 108 -11Q95 -11 87 -5T76 7T74 17Q74 30 112 180T152 343Q153 348 153 366Q153 405 129 405Q91 405 66 305Q60 285 60 284Q58 278 41 278H27Q21 284 21 287Z"></path></g></g></g></svg></mjx-container> 为当前询问字符串的长度。</p>
<p>考虑如何优化。容易发现,内层的 DP 是一个比较显然的滑动窗口的模型,因此我们直接套用一个单调队列来优化即可,这样 DP 部分就可以做到 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.566ex;" xmlns="http://www.w3.org/2000/svg" width="9.922ex" height="2.262ex" role="img" focusable="false" viewBox="0 -750 4385.3 1000"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="TeXAtom" data-mjx-texclass="ORD"><g data-mml-node="mi"><path data-c="4F" d="M308 428Q289 428 289 438Q289 457 318 508T378 593Q417 638 475 671T599 705Q688 705 732 643T777 483Q777 380 733 285T620 123T464 18T293 -22Q188 -22 123 51T58 245Q58 327 87 403T159 533T249 626T333 685T388 705Q404 705 404 693Q404 674 363 649Q333 632 304 606T239 537T181 429T158 290Q158 179 214 114T364 48Q489 48 583 165T677 438Q677 473 670 505T648 568T601 617T528 636Q518 636 513 635Q486 629 460 600T419 544T392 490Q383 470 372 459Q341 430 308 428Z"></path></g></g><g data-mml-node="mo" transform="translate(796,0)"><path data-c="28" d="M94 250Q94 319 104 381T127 488T164 576T202 643T244 695T277 729T302 750H315H319Q333 750 333 741Q333 738 316 720T275 667T226 581T184 443T167 250T184 58T225 -81T274 -167T316 -220T333 -241Q333 -250 318 -250H315H302L274 -226Q180 -141 137 -14T94 250Z"></path></g><g data-mml-node="mi" transform="translate(1185,0)"><path data-c="1D45B" d="M21 287Q22 293 24 303T36 341T56 388T89 425T135 442Q171 442 195 424T225 390T231 369Q231 367 232 367L243 378Q304 442 382 442Q436 442 469 415T503 336T465 179T427 52Q427 26 444 26Q450 26 453 27Q482 32 505 65T540 145Q542 153 560 153Q580 153 580 145Q580 144 576 130Q568 101 554 73T508 17T439 -10Q392 -10 371 17T350 73Q350 92 386 193T423 345Q423 404 379 404H374Q288 404 229 303L222 291L189 157Q156 26 151 16Q138 -11 108 -11Q95 -11 87 -5T76 7T74 17Q74 30 112 180T152 343Q153 348 153 366Q153 405 129 405Q91 405 66 305Q60 285 60 284Q58 278 41 278H27Q21 284 21 287Z"></path></g><g data-mml-node="mi" transform="translate(1951.7,0)"><path data-c="6C" d="M42 46H56Q95 46 103 60V68Q103 77 103 91T103 124T104 167T104 217T104 272T104 329Q104 366 104 407T104 482T104 542T103 586T103 603Q100 622 89 628T44 637H26V660Q26 683 28 683L38 684Q48 685 67 686T104 688Q121 689 141 690T171 693T182 694H185V379Q185 62 186 60Q190 52 198 49Q219 46 247 46H263V0H255L232 1Q209 2 183 2T145 3T107 3T57 1L34 0H26V46H42Z"></path><path data-c="6F" d="M28 214Q28 309 93 378T250 448Q340 448 405 380T471 215Q471 120 407 55T250 -10Q153 -10 91 57T28 214ZM250 30Q372 30 372 193V225V250Q372 272 371 288T364 326T348 362T317 390T268 410Q263 411 252 411Q222 411 195 399Q152 377 139 338T126 246V226Q126 130 145 91Q177 30 250 30Z" transform="translate(278,0)"></path><path data-c="67" d="M329 409Q373 453 429 453Q459 453 472 434T485 396Q485 382 476 371T449 360Q416 360 412 390Q410 404 415 411Q415 412 416 414V415Q388 412 363 393Q355 388 355 386Q355 385 359 381T368 369T379 351T388 325T392 292Q392 230 343 187T222 143Q172 143 123 171Q112 153 112 133Q112 98 138 81Q147 75 155 75T227 73Q311 72 335 67Q396 58 431 26Q470 -13 470 -72Q470 -139 392 -175Q332 -206 250 -206Q167 -206 107 -175Q29 -140 29 -75Q29 -39 50 -15T92 18L103 24Q67 55 67 108Q67 155 96 193Q52 237 52 292Q52 355 102 398T223 442Q274 442 318 416L329 409ZM299 343Q294 371 273 387T221 404Q192 404 171 388T145 343Q142 326 142 292Q142 248 149 227T179 192Q196 182 222 182Q244 182 260 189T283 207T294 227T299 242Q302 258 302 292T299 343ZM403 -75Q403 -50 389 -34T348 -11T299 -2T245 0H218Q151 0 138 -6Q118 -15 107 -34T95 -74Q95 -84 101 -97T122 -127T170 -155T250 -167Q319 -167 361 -139T403 -75Z" transform="translate(778,0)"></path></g><g data-mml-node="mo" transform="translate(3229.7,0)"><path data-c="2061" d=""></path></g><g data-mml-node="mi" transform="translate(3396.3,0)"><path data-c="1D45B" d="M21 287Q22 293 24 303T36 341T56 388T89 425T135 442Q171 442 195 424T225 390T231 369Q231 367 232 367L243 378Q304 442 382 442Q436 442 469 415T503 336T465 179T427 52Q427 26 444 26Q450 26 453 27Q482 32 505 65T540 145Q542 153 560 153Q580 153 580 145Q580 144 576 130Q568 101 554 73T508 17T439 -10Q392 -10 371 17T350 73Q350 92 386 193T423 345Q423 404 379 404H374Q288 404 229 303L222 291L189 157Q156 26 151 16Q138 -11 108 -11Q95 -11 87 -5T76 7T74 17Q74 30 112 180T152 343Q153 348 153 366Q153 405 129 405Q91 405 66 305Q60 285 60 284Q58 278 41 278H27Q21 284 21 287Z"></path></g><g data-mml-node="mo" transform="translate(3996.3,0)"><path data-c="29" d="M60 749L64 750Q69 750 74 750H86L114 726Q208 641 251 514T294 250Q294 182 284 119T261 12T224 -76T186 -143T145 -194T113 -227T90 -246Q87 -249 86 -250H74Q66 -250 63 -250T58 -247T55 -238Q56 -237 66 -225Q221 -64 221 250T66 725Q56 737 55 738Q55 746 60 749Z"></path></g></g></g></svg></mjx-container> 了。</p>
<p>然后再来考虑怎么求这个 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.025ex;" xmlns="http://www.w3.org/2000/svg" width="3.086ex" height="1.595ex" role="img" focusable="false" viewBox="0 -694 1364 705"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="mi"><path data-c="1D459" d="M117 59Q117 26 142 26Q179 26 205 131Q211 151 215 152Q217 153 225 153H229Q238 153 241 153T246 151T248 144Q247 138 245 128T234 90T214 43T183 6T137 -11Q101 -11 70 11T38 85Q38 97 39 102L104 360Q167 615 167 623Q167 626 166 628T162 632T157 634T149 635T141 636T132 637T122 637Q112 637 109 637T101 638T95 641T94 647Q94 649 96 661Q101 680 107 682T179 688Q194 689 213 690T243 693T254 694Q266 694 266 686Q266 675 193 386T118 83Q118 81 118 75T117 65V59Z"></path></g><g data-mml-node="mi" transform="translate(298,0)"><path data-c="1D452" d="M39 168Q39 225 58 272T107 350T174 402T244 433T307 442H310Q355 442 388 420T421 355Q421 265 310 237Q261 224 176 223Q139 223 138 221Q138 219 132 186T125 128Q125 81 146 54T209 26T302 45T394 111Q403 121 406 121Q410 121 419 112T429 98T420 82T390 55T344 24T281 -1T205 -11Q126 -11 83 42T39 168ZM373 353Q367 405 305 405Q272 405 244 391T199 357T170 316T154 280T149 261Q149 260 169 260Q282 260 327 284T373 353Z"></path></g><g data-mml-node="mi" transform="translate(764,0)"><path data-c="1D45B" d="M21 287Q22 293 24 303T36 341T56 388T89 425T135 442Q171 442 195 424T225 390T231 369Q231 367 232 367L243 378Q304 442 382 442Q436 442 469 415T503 336T465 179T427 52Q427 26 444 26Q450 26 453 27Q482 32 505 65T540 145Q542 153 560 153Q580 153 580 145Q580 144 576 130Q568 101 554 73T508 17T439 -10Q392 -10 371 17T350 73Q350 92 386 193T423 345Q423 404 379 404H374Q288 404 229 303L222 291L189 157Q156 26 151 16Q138 -11 108 -11Q95 -11 87 -5T76 7T74 17Q74 30 112 180T152 343Q153 348 153 366Q153 405 129 405Q91 405 66 305Q60 285 60 284Q58 278 41 278H27Q21 284 21 287Z"></path></g></g></g></svg></mjx-container>。这个当然是比较简单的,我们把原串组织成一棵广义 SAM,那么求 len 的过程就类似于使用 SAM 求 LCS 的过程,我们直接跳 link 树即可。这部分的时间复杂度为 <mjx-container class="MathJax" jax="SVG"><svg style="vertical-align: -0.566ex;" xmlns="http://www.w3.org/2000/svg" width="17.732ex" height="2.262ex" role="img" focusable="false" viewBox="0 -750 7837.7 1000"><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="scale(1,-1)"><g data-mml-node="math"><g data-mml-node="TeXAtom" data-mjx-texclass="ORD"><g data-mml-node="mi"><path data-c="4F" d="M308 428Q289 428 289 438Q289 457 318 508T378 593Q417 638 475 671T599 705Q688 705 732 643T777 483Q777 380 733 285T620 123T464 18T293 -22Q188 -22 123 51T58 245Q58 327 87 403T159 533T249 626T333 685T388 705Q404 705 404 693Q404 674 363 649Q333 632 304 606T239 537T181 429T158 290Q158 179 214 114T364 48Q489 48 583 165T677 438Q677 473 670 505T648 568T601 617T528 636Q518 636 513 635Q486 629 460 600T419 544T392 490Q383 470 372 459Q341 430 308 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-249 119 -235V251L120 737Q130 750 139 750Q152 750 159 735V-235Q151 -249 141 -249H139Z"></path></g><g data-mml-node="msub" transform="translate(2685.7,0)"><g data-mml-node="mi"><path data-c="1D460" d="M131 289Q131 321 147 354T203 415T300 442Q362 442 390 415T419 355Q419 323 402 308T364 292Q351 292 340 300T328 326Q328 342 337 354T354 372T367 378Q368 378 368 379Q368 382 361 388T336 399T297 405Q249 405 227 379T204 326Q204 301 223 291T278 274T330 259Q396 230 396 163Q396 135 385 107T352 51T289 7T195 -10Q118 -10 86 19T53 87Q53 126 74 143T118 160Q133 160 146 151T160 120Q160 94 142 76T111 58Q109 57 108 57T107 55Q108 52 115 47T146 34T201 27Q237 27 263 38T301 66T318 97T323 122Q323 150 302 164T254 181T195 196T148 231Q131 256 131 289Z"></path></g><g data-mml-node="mi" transform="translate(502,-150) scale(0.707)"><path data-c="1D456" d="M184 600Q184 624 203 642T247 661Q265 661 277 649T290 619Q290 596 270 577T226 557Q211 557 198 567T184 600ZM21 287Q21 295 30 318T54 369T98 420T158 442Q197 442 223 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735V-235Q151 -249 141 -249H139Z"></path></g><g data-mml-node="mo" transform="translate(7448.7,0)"><path data-c="29" d="M60 749L64 750Q69 750 74 750H86L114 726Q208 641 251 514T294 250Q294 182 284 119T261 12T224 -76T186 -143T145 -194T113 -227T90 -246Q87 -249 86 -250H74Q66 -250 63 -250T58 -247T55 -238Q56 -237 66 -225Q221 -64 221 250T66 725Q56 737 55 738Q55 746 60 749Z"></path></g></g></g></svg></mjx-container> 的。</p>
<p>于是这样这道题就做完了!</p>
<figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br><span class="line">68</span><br><span class="line">69</span><br><span class="line">70</span><br><span class="line">71</span><br><span class="line">72</span><br><span class="line">73</span><br><span class="line">74</span><br><span class="line">75</span><br><span class="line">76</span><br><span class="line">77</span><br><span class="line">78</span><br><span class="line">79</span><br><span class="line">80</span><br><span class="line">81</span><br><span class="line">82</span><br><span class="line">83</span><br><span class="line">84</span><br><span class="line">85</span><br><span class="line">86</span><br><span class="line">87</span><br><span class="line">88</span><br><span class="line">89</span><br><span class="line">90</span><br><span class="line">91</span><br><span class="line">92</span><br><span class="line">93</span><br><span class="line">94</span><br><span class="line">95</span><br><span class="line">96</span><br><span class="line">97</span><br><span class="line">98</span><br><span class="line">99</span><br><span class="line">100</span><br><span class="line">101</span><br><span class="line">102</span><br><span class="line">103</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string"><bits/stdc++.h></span></span></span><br><span class="line"></span><br><span class="line"><span class="keyword">using</span> i64 = <span class="type">long</span> <span class="type">long</span>;</span><br><span class="line"></span><br><span class="line"><span class="keyword">constexpr</span> <span class="type">int</span> N = <span class="number">2e6</span> + <span class="number">50</span>;</span><br><span class="line"></span><br><span class="line"><span class="type">int</span> n, m;</span><br><span class="line"></span><br><span class="line"><span class="type">int</span> f[N], g[N];</span><br><span class="line"></span><br><span class="line"><span class="keyword">struct</span> <span class="title class_">GSAM</span> {</span><br><span class="line"> <span class="type">int</span> ch[N][<span class="number">2</span>], len[N], link[N], cnt = <span class="number">1</span>;</span><br><span class="line"> <span class="function"><span class="type">int</span> <span class="title">expand</span><span class="params">(<span class="type">int</span> lst, <span class="type">int</span> d)</span> </span>{</span><br><span class="line"> <span class="type">int</span> p = lst;</span><br><span class="line"> <span class="keyword">if</span> (<span class="type">int</span> q = ch[p][d]) {</span><br><span class="line"> <span class="keyword">if</span> (len[p] + <span class="number">1</span> == len[q]) {</span><br><span class="line"> <span class="keyword">return</span> q;</span><br><span class="line"> } <span class="keyword">else</span> {</span><br><span class="line"> <span class="type">int</span> tmp = ++cnt;</span><br><span class="line"> len[tmp] = len[p] + <span class="number">1</span>, link[tmp] = link[q];</span><br><span class="line"> <span class="built_in">memcpy</span>(ch[tmp], ch[q], <span class="built_in">sizeof</span>(ch[tmp]));</span><br><span class="line"> <span class="keyword">for</span> (; p && ch[p][d] == q; p = link[p]) ch[p][d] = tmp;</span><br><span class="line"> link[q] = tmp;</span><br><span class="line"> <span class="keyword">return</span> tmp;</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> <span class="type">int</span> cur = ++cnt;</span><br><span class="line"> len[cur] = len[p] + <span class="number">1</span>;</span><br><span class="line"> <span class="keyword">for</span> (; p && !ch[p][d]; p = link[p]) ch[p][d] = cur;</span><br><span class="line"> <span class="keyword">if</span> (!p) {</span><br><span class="line"> link[cur] = <span class="number">1</span>;</span><br><span class="line"> } <span class="keyword">else</span> {</span><br><span class="line"> <span class="type">int</span> q = ch[p][d];</span><br><span class="line"> <span class="keyword">if</span> (len[p] + <span class="number">1</span> == len[q]) {</span><br><span class="line"> link[cur] = q;</span><br><span class="line"> } <span class="keyword">else</span> {</span><br><span class="line"> <span class="type">int</span> tmp = ++cnt;</span><br><span class="line"> len[tmp] = len[p] + <span class="number">1</span>, link[tmp] = link[q];</span><br><span class="line"> <span class="built_in">memcpy</span>(ch[tmp], ch[q], <span class="built_in">sizeof</span>(ch[tmp]));</span><br><span class="line"> <span class="keyword">for</span> (; p && ch[p][d] == q; p = link[p]) ch[p][d] = tmp;</span><br><span class="line"> link[cur] = link[q] = tmp;</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">return</span> cur;</span><br><span class="line"> }</span><br><span class="line"> <span class="function"><span class="type">void</span> <span class="title">match</span><span class="params">(std::string_view s)</span> </span>{</span><br><span class="line"> <span class="type">int</span> p = <span class="number">1</span>;</span><br><span class="line"> <span class="keyword">for</span> (<span class="type">int</span> i = <span class="number">1</span>, cur = <span class="number">0</span>; i <= <span class="built_in">int</span>(s.<span class="built_in">length</span>()); i++) {</span><br><span class="line"> <span class="type">int</span> d = s[i - <span class="number">1</span>] - <span class="string">'0'</span>;</span><br><span class="line"> <span class="keyword">while</span> (p != <span class="number">1</span> && !ch[p][d]) p = link[p], cur = len[p];</span><br><span class="line"> <span class="keyword">if</span> (ch[p][d]) p = ch[p][d], cur = std::<span class="built_in">min</span>(cur + <span class="number">1</span>, len[p]);</span><br><span class="line"> g[i] = cur;</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line">} gsam;</span><br><span class="line"></span><br><span class="line">std::string s;</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">bool</span> <span class="title">check</span><span class="params">(<span class="type">int</span> u)</span> </span>{</span><br><span class="line"> <span class="type">static</span> <span class="type">int</span> q[N], hd = <span class="number">1</span>, tl = <span class="number">0</span>;</span><br><span class="line"></span><br><span class="line"> <span class="keyword">for</span> (<span class="type">int</span> i = <span class="number">0</span>; i < u; i++) f[i] = <span class="number">0</span>;</span><br><span class="line"> q[hd = tl = <span class="number">1</span>] = <span class="number">0</span>;</span><br><span class="line"> <span class="keyword">for</span> (<span class="type">int</span> i = u; i <= <span class="built_in">int</span>(s.<span class="built_in">length</span>()); i++) {</span><br><span class="line"> f[i] = f[i - <span class="number">1</span>];</span><br><span class="line"> <span class="keyword">while</span> (hd <= tl && f[i - u] - (i - u) >= f[q[tl]] - q[tl]) tl--;</span><br><span class="line"> q[++tl] = i - u;</span><br><span class="line"> <span class="keyword">while</span> (hd <= tl && q[hd] < i - g[i]) hd++;</span><br><span class="line"> <span class="keyword">if</span> (hd <= tl) f[i] = std::<span class="built_in">max</span>(f[i], f[q[hd]] + i - q[hd]);</span><br><span class="line"> }</span><br><span class="line"></span><br><span class="line"> <span class="keyword">return</span> f[s.<span class="built_in">length</span>()] * <span class="number">10u</span> >= s.<span class="built_in">length</span>() * <span class="number">9</span>;</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">solve</span><span class="params">()</span> </span>{</span><br><span class="line"> std::cin >> n >> m;</span><br><span class="line"> <span class="keyword">for</span> (<span class="type">int</span> i = <span class="number">1</span>, lst = <span class="number">1</span>; i <= m; i++, lst = <span class="number">1</span>) {</span><br><span class="line"> std::cin >> s;</span><br><span class="line"> <span class="keyword">for</span> (<span class="keyword">auto</span> c : s) lst = gsam.<span class="built_in">expand</span>(lst, c - <span class="string">'0'</span>);</span><br><span class="line"> }</span><br><span class="line"></span><br><span class="line"> <span class="keyword">for</span> (<span class="type">int</span> i = <span class="number">1</span>; i <= n; i++) {</span><br><span class="line"> std::cin >> s;</span><br><span class="line"> <span class="type">int</span> lo = <span class="number">0</span>, hi = s.<span class="built_in">length</span>(), ans = <span class="number">0</span>;</span><br><span class="line"> gsam.<span class="built_in">match</span>(s);</span><br><span class="line"> <span class="keyword">while</span> (lo <= hi) {</span><br><span class="line"> <span class="type">int</span> mid = (lo + hi) >> <span class="number">1</span>;</span><br><span class="line"> <span class="keyword">if</span> (<span class="built_in">check</span>(mid)) lo = mid + <span class="number">1</span>, ans = mid;</span><br><span class="line"> <span class="keyword">else</span> hi = mid - <span class="number">1</span>;</span><br><span class="line"> }</span><br><span class="line"> std::cout << ans << <span class="string">"\n"</span>;</span><br><span class="line"> }</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">signed</span> <span class="title">main</span><span class="params">()</span> </span>{</span><br><span class="line"> std::cin.<span class="built_in">tie</span>(<span class="literal">nullptr</span>)-><span class="built_in">sync_with_stdio</span>(<span class="literal">false</span>);</span><br><span class="line"></span><br><span class="line"> <span class="type">int</span> t = <span class="number">1</span>;</span><br><span class="line"> <span class="comment">// std::cin >> t;</span></span><br><span class="line"> <span class="keyword">while</span> (t--) <span class="built_in">solve</span>();</span><br><span class="line"> </span><br><span class="line"> <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">}</span><br></pre></td></tr></table></figure>
</div></article></div><div class="card"><article class="card-content article" role="article"><div class="article-meta is-size-7 is-uppercase level is-mobile"><div class="level-left"><span class="level-item"><time dateTime="2024-01-17T11:24:23.000Z" title="2024/1/17 19:24:23">2024-01-17</time>发表</span><span class="level-item"><time dateTime="2024-01-18T07:06:41.890Z" title="2024/1/18 15:06:41">2024-01-18</time>更新</span><span class="level-item"><a class="link-muted" href="/categories/Other/">Other</a></span><span class="level-item">几秒读完 (大约12个字)</span></div></div><p class="title is-3 is-size-4-mobile"><a class="link-muted" href="/2024/01/17/test/">test</a></p><div class="content"><h1 id="Test-File"><a href="#Test-File" class="headerlink" title="Test File"></a>Test File</h1><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string"><iostream></span></span></span><br><span class="line"></span><br><span class="line"><=</span><br><span class="line"></span><br><span class="line">>=</span><br><span class="line"></span><br><span class="line">==</span><br></pre></td></tr></table></figure>
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</div></article></div><div class="card"><article class="card-content article" role="article"><div class="article-meta is-size-7 is-uppercase level is-mobile"><div class="level-left"><span class="level-item"><time dateTime="2024-01-17T10:54:26.327Z" title="2024/1/17 18:54:26">2024-01-17</time>发表</span><span class="level-item"><time dateTime="2024-01-17T10:54:26.327Z" title="2024/1/17 18:54:26">2024-01-17</time>更新</span><span class="level-item">1 分钟读完 (大约123个字)</span></div></div><p class="title is-3 is-size-4-mobile"><a class="link-muted" href="/2024/01/17/hello-world/">Hello World</a></p><div class="content"><p>Welcome to <a target="_blank" rel="noopener" href="https://hexo.io/">Hexo</a>! This is your very first post. Check <a target="_blank" rel="noopener" href="https://hexo.io/docs/">documentation</a> for more info. If you get any problems when using Hexo, you can find the answer in <a target="_blank" rel="noopener" href="https://hexo.io/docs/troubleshooting.html">troubleshooting</a> or you can ask me on <a target="_blank" rel="noopener" href="https://github.com/hexojs/hexo/issues">GitHub</a>.</p>
<h2 id="Quick-Start"><a href="#Quick-Start" class="headerlink" title="Quick Start"></a>Quick Start</h2><h3 id="Create-a-new-post"><a href="#Create-a-new-post" class="headerlink" title="Create a new post"></a>Create a new post</h3><figure class="highlight bash"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">$ hexo new <span class="string">"My New Post"</span></span><br></pre></td></tr></table></figure>
<p>More info: <a target="_blank" rel="noopener" href="https://hexo.io/docs/writing.html">Writing</a></p>
<h3 id="Run-server"><a href="#Run-server" class="headerlink" title="Run server"></a>Run server</h3><figure class="highlight bash"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">$ hexo server</span><br></pre></td></tr></table></figure>
<p>More info: <a target="_blank" rel="noopener" href="https://hexo.io/docs/server.html">Server</a></p>
<h3 id="Generate-static-files"><a href="#Generate-static-files" class="headerlink" title="Generate static files"></a>Generate static files</h3><figure class="highlight bash"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">$ hexo generate</span><br></pre></td></tr></table></figure>
<p>More info: <a target="_blank" rel="noopener" href="https://hexo.io/docs/generating.html">Generating</a></p>
<h3 id="Deploy-to-remote-sites"><a href="#Deploy-to-remote-sites" class="headerlink" title="Deploy to remote sites"></a>Deploy to remote sites</h3><figure class="highlight bash"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">$ hexo deploy</span><br></pre></td></tr></table></figure>
<p>More info: <a target="_blank" rel="noopener" href="https://hexo.io/docs/one-command-deployment.html">Deployment</a></p>
</div></article></div></div><div class="column column-left is-4-tablet is-4-desktop is-4-widescreen order-1"><div class="card widget" data-type="profile"><div class="card-content"><nav class="level"><div class="level-item has-text-centered flex-shrink-1"><div><figure class="image is-128x128 mx-auto mb-2"><img class="avatar is-rounded" src="/img/avatar.jpg" alt="ForgotDream"></figure><p class="title is-size-4 is-block" style="line-height:inherit;">ForgotDream</p><p class="is-size-6 is-block">傻逼</p><p class="is-size-6 is-flex justify-content-center"><i class="fas fa-map-marker-alt mr-1"></i><span>Gensokyo</span></p></div></div></nav><nav class="level is-mobile"><div class="level-item has-text-centered is-marginless"><div><p class="heading">文章</p><a href="/archives"><p class="title">8</p></a></div></div><div class="level-item has-text-centered is-marginless"><div><p class="heading">分类</p><a href="/categories"><p class="title">5</p></a></div></div><div class="level-item has-text-centered 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