LeetCode Blind 75 Solutions

This repository contains my solutions to the LeetCode Blind 75 problems, organized by category.
Checked means the problem is solved and present in the repository.

Progress Statistics

• Easy: 19 / 19 solved (100.0 %)
• Medium: 49 / 49 solved (100.0 %)
• Hard: 7 / 7 solved (100.0 %)
• Total: 75 / 75 solved (100.0 %)

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Arrays & Hashing

ID	Level	Done	Problem	Solution
01	Easy	✅	217. Contains Duplicate	Solution
02	Easy	✅	242. Valid Anagram	Solution
03	Easy	✅	1. Two Sum	Solution
04	Medium	✅	49. Group Anagrams	Solution
05	Medium	✅	347. Top K Frequent Elements	Solution
06	Medium	✅	238. Product of Array Except Self	Solution
07	Medium	✅	271. Encode and Decode Strings	Solution
08	Medium	✅	128. Longest Consecutive Sequence	Solution

Two Pointers

ID	Level	Done	Problem	Solution
09	Easy	✅	125. Valid Palindrome	Solution
10	Medium	✅	15. 3Sum	Solution
11	Medium	✅	11. Container With Most Water	Solution

Sliding Window

ID	Level	Done	Problem	Solution
12	Easy	✅	121. Best Time to Buy and Sell Stock	Solution
13	Medium	✅	3. Longest Substring Without Repeating Characters	Solution
14	Medium	✅	424. Longest Repeating Character Replacement	Solution
15	Hard	✅	76. Minimum Window Substring	Solution

Stack

ID	Level	Done	Problem	Solution
16	Easy	✅	20. Valid Parentheses	Solution

Binary Search

ID	Level	Done	Problem	Solution
17	Medium	✅	33. Search in Rotated Sorted Array	Solution
18	Medium	✅	153. Find Minimum in Rotated Sorted Array	Solution

Linked List

ID	Level	Done	Problem	Solution
19	Easy	✅	206. Reverse Linked List	Solution
20	Easy	✅	21. Merge Two Sorted Lists	Solution
21	Easy	✅	141. Linked List Cycle	Solution
22	Medium	✅	19. Remove Nth Node From End of List	Solution
23	Medium	✅	143. Reorder List	Solution
24	Hard	✅	23. Merge k Sorted Lists	Solution

Trees

ID	Level	Done	Problem	Solution
25	Easy	✅	226. Invert Binary Tree	Solution
26	Easy	✅	104. Maximum Depth of Binary Tree	Solution
27	Easy	✅	100. Same Tree	Solution
28	Easy	✅	572. Subtree of Another Tree	Solution
29	Medium	✅	235. Lowest Common Ancestor of a Binary Search Tree	Solution
30	Medium	✅	102. Binary Tree Level Order Traversal	Solution
31	Medium	✅	98. Validate Binary Search Tree	Solution
32	Medium	✅	230. Kth Smallest Element in a BST	Solution
33	Medium	✅	105. Construct Binary Tree from Preorder and Inorder Traversal	Solution
34	Hard	✅	124. Binary Tree Maximum Path Sum	Solution
35	Hard	✅	297. Serialize and Deserialize Binary Tree	Solution

Tries

ID	Level	Done	Problem	Solution
36	Medium	✅	208. Implement Trie (Prefix Tree)	Solution
37	Medium	✅	211. Design Add and Search Words Data Structure	Solution
38	Hard	✅	212. Word Search II	Solution

Heap & Priority Queue

ID	Level	Done	Problem	Solution
39	Hard	✅	295. Find Median from Data Stream	Solution

Backtracking

ID	Level	Done	Problem	Solution
40	Medium	✅	39. Combination Sum	Solution
41	Medium	✅	79. Word Search	Solution

Graphs

ID	Level	Done	Problem	Solution
42	Medium	✅	200. Number of Islands	Solution
43	Medium	✅	133. Clone Graph	Solution
44	Medium	✅	417. Pacific Atlantic Water Flow	Solution
45	Medium	✅	207. Course Schedule	Solution
46	Medium	✅	323. Number of Connected Components in an Undirected Graph	Solution
47	Medium	✅	261. Graph Valid Tree	Solution

Advanced Graphs

ID	Level	Done	Problem	Solution
48	Hard	✅	269. Alien Dictionary	Solution

1-D Dynamic Programming

ID	Level	Done	Problem	Solution
49	Easy	✅	70. Climbing Stairs	Solution
50	Medium	✅	198. House Robber	Solution
51	Medium	✅	213. House Robber II	Solution
52	Medium	✅	5. Longest Palindromic Substring	Solution
53	Medium	✅	647. Palindromic Substrings	Solution
54	Medium	✅	91. Decode Ways	Solution
55	Medium	✅	322. Coin Change	Solution
56	Medium	✅	152. Maximum Product Subarray	Solution
57	Medium	✅	139. Word Break	Solution
58	Medium	✅	300. Longest Increasing Subsequence	Solution

2-D Dynamic Programming

ID	Level	Done	Problem	Solution
59	Medium	✅	62. Unique Paths	Solution
60	Medium	✅	1143. Longest Common Subsequence	Solution

Greedy

ID	Level	Done	Problem	Solution
61	Medium	✅	53. Maximum Subarray	Solution
62	Medium	✅	55. Jump Game	Solution

Intervals

ID	Level	Done	Problem	Solution
63	Easy	✅	252. Meeting Rooms	Solution
64	Medium	✅	253. Meeting Rooms II	Solution
65	Medium	✅	57. Insert Interval	Solution
66	Medium	✅	56. Merge Intervals	Solution
67	Medium	✅	435. Non-overlapping Intervals	Solution

Math & Geometry

ID	Level	Done	Problem	Solution
68	Medium	✅	48. Rotate Image	Solution
69	Medium	✅	54. Spiral Matrix	Solution
70	Medium	✅	73. Set Matrix Zeroes	Solution

Bit Manipulation

ID	Level	Done	Problem	Solution
71	Easy	✅	191. Number of 1 Bits	Solution
72	Easy	✅	338. Counting Bits	Solution
73	Easy	✅	190. Reverse Bits	Solution
74	Easy	✅	268. Missing Number	Solution
75	Medium	✅	371. Sum of Two Integers	Solution

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Running Solutions

To run the solutions, you need Python 3.6 or higher.

Example:

python arrays-and-hashing/1-two-sum/main.py

Requirements

• Python 3.6+
• typing (built-in in Python 3.5+)

Environment Setup

Install the following VS Code extensions:

• Python (ms-python.python)
• Pylance (ms-python.vscode-pylance)
• Black Formatter (ms-python.black-formatter)

Install the required Python packages:

pip install black pylint

Automatic Formatting

The project is set up for automatic code formatting on save using Black. For manual formatting, use:

• Windows/Linux: Shift + Alt + F
• Mac: Shift + Option + F