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Merged
omn7 merged 1 commit into from
Apr 4, 2026
Merged

Add 4Sum Better and Optimal Java code blocks to index.html for display #5

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79 changes: 79 additions & 0 deletions index.html
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Original file line number Diff line number Diff line change
Expand Up @@ -457,6 +457,85 @@
</head>
<body>
<div class="container mt-5">
<h2>4Sum Better</h2>
<pre><code class="language-java">import java.util.*;

public class FourSumBetter {
public List<List<Integer>> fourSum(int[] nums, int target) {
int n = nums.length;
Set<List<Integer>> set = new HashSet<>();
for (int i = 0; i < n; i++) {
for (int j = i + 1; j < n; j++) {
HashSet<Long> seen = new HashSet<>();
for (int k = j + 1; k < n; k++) {
long sum = (long) nums[i] + nums[j] + nums[k];
long needed = (long) target - sum;
if (seen.contains(needed)) {
List<Integer> temp = Arrays.asList(nums[i], nums[j], nums[k], (int) needed);
Collections.sort(temp);
set.add(temp);
}
seen.add((long) nums[k]);
}
}
}
return new ArrayList<>(set);
}

public static void main(String[] args) {
FourSumBetter sol = new FourSumBetter();
int[] nums = {1, 0, -1, 0, -2, 2}; // Example input
int target = 0;
List<List<Integer>> result = sol.fourSum(nums, target);
System.out.println("Quadruplets that sum to target: " + result);
}
}
</code></pre>

<h2>4Sum Optimal</h2>
<pre><code class="language-java">import java.util.*;

public class FourSumOptimal {
public List<List<Integer>> fourSum(int[] nums, int target) {
int n = nums.length;
List<List<Integer>> ans = new ArrayList<>();
Arrays.sort(nums);
for (int i = 0; i < n - 3; i++) {
if (i > 0 && nums[i] == nums[i - 1]) continue;
for (int j = i + 1; j < n - 2; j++) {
if (j > i + 1 && nums[j] == nums[j - 1]) continue;
int k = j + 1;
int l = n - 1;
while (k < l) {
long sum = (long) nums[i] + nums[j] + nums[k] + nums[l];
if (sum == target) {
ans.add(Arrays.asList(nums[i], nums[j], nums[k], nums[l]));
while (k < l && nums[k] == nums[k + 1]) k++;
while (k < l && nums[l] == nums[l - 1]) l--;
k++;
l--;
}
else if (sum < target) {
k++;
}
else {
l--;
}
}
}
}
return ans;
}

public static void main(String[] args) {
FourSumOptimal sol = new FourSumOptimal();
int[] nums = {1, 0, -1, 0, -2, 2}; // Example input
int target = 0;
List<List<Integer>> result = sol.fourSum(nums, target);
System.out.println("Quadruplets that sum to target: " + result);
}
}
</code></pre>
<h2>3Sum Brute</h2>
<pre><code class="language-java">import java.util.*;

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