| 1 | 1. Two Sum | Array | Array Manipulate / Hashing | Easy | | | | |
| 2 | 217. Contains Duplicate | Array | Array Manipulate / Hashing | Easy | | | | |
| 3 | 242. Valid Anagram | String | String Manipulate / Hashing | Easy | | | | |
| 4 | 49. Group Anagrams | String | String Manipulate / Hashing | Medium | | | | |
| 5 | 347. Top K Frequent Elements | Array | Array Manipulate / Hashing | Medium | | | | |
| 6 | 392. Is Subsequence | String | String Manipulate / Hashing | Easy | | | | |
| 7 | 128. Longest Consecutive Sequence | Array | Array Manipulate / Hashing | Medium | | | | |
| 8 | 238. Product of Array Except Self | Array | Array Manipulate / Hashing | Medium | | | | |
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| 9 | 125. Valid Palindrome | String | Two Pointers | Easy | | | | |
| 10 | 167. Two Sum II Input Array Is Sorted | Array | Two Pointers | Medium | | | | |
| 11 | 15. 3Sum | Array | Two Pointers | Medium | | | | |
| 12 | 11. Container With Most Water | Array | Two Pointers | Medium | | | | |
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| 13 | 643. Maximum Average Subarray I | Array | Sliding Window | Easy | | | | |
| 14 | 121. Best Time to Buy and Sell Stock | Array | Sliding Window | Easy | | | | |
| 15 | 424. Longest Repeating Character Replacement | String | Sliding Window | Medium | | | | |
| 16 | 3. Longest Substring Without Repeating Characters | String | Sliding Window | Medium | | | | |
| 17 | 76. Minimum Window Substring | String | Sliding Window | Hard | | | | |
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| 18 | 876. Middle of the Linked List | Linked List | Fast & Slow Pointers | Easy | | | | |
| 19 | 141. Linked List Cycle | Linked List | Fast & Slow Pointers | Easy | | | | |
| 20 | 142. Linked List Cycle II | Linked List | Fast & Slow Pointers | Medium | | | | |
| 21 | 206. Reverse Linked List | Linked List | Fast & Slow Pointers | Easy | | | | |
| 22 | 143. Reorder List | Linked List | Fast & Slow Pointers | Medium | | | | |
| 23 | 19. Remove Nth Node From End of List | Linked List | Fast & Slow Pointers | Medium | | | | |
| 24 | 21. Merge Two Sorted Lists | Linked List | Fast & Slow Pointers | Easy | | | | |
| 25 | 23. Merge K Sorted Lists | Linked List | Fast & Slow Pointers | Hard | | | | |
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| 26 | 20. Valid Parentheses | Stack | Stack / Monotonic Stack | Easy | | | | |
| 27 | 739. Daily Temperatures | Stack | Stack / Monotonic Stack | Medium | | | | |
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| 28 | 704. Binary Search | Binary Search | Binary Search | Easy | | | | |
| 29 | 153. Find Minimum in Rotated Sorted Array | Binary Search | Binary Search | Medium | | | | |
| 30 | 33. Search in Rotated Sorted Array | Binary Search | Binary Search | Medium | | | | |
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| 31 | 226. Invert Binary Tree | Trees | DFS / BFS | Easy | | | | |
| 32 | 104. Maximum Depth of Binary Tree | Trees | DFS / BFS | Easy | | | | |
| 33 | 100. Same Tree | Trees | DFS / BFS | Easy | | | | |
| 34 | 572. Subtree of Another Tree | Trees | DFS / BFS | Easy | | | | |
| 35 | 235. Lowest Common Ancestor of a Binary Search Tree | Trees | DFS / BFS | Medium | | | | |
| 36 | 102. Binary Tree Level Order Traversal | Trees | DFS / BFS | Medium | | | | |
| 37 | 98. Validate Binary Search Tree | Trees | DFS / BFS | Medium | | | | |
| 38 | 230. Kth Smallest Element in a BST | Trees | DFS / BFS | Medium | | | | |
| 39 | 105. Construct Binary Tree from Preorder and Inorder Traversal | Trees | DFS / BFS | Medium | | | | |
| 40 | 124. Binary Tree Maximum Path Sum | Trees | DFS / BFS | Hard | | | | |
| 41 | 297. Serialize and Deserialize Binary Tree | Trees | DFS / BFS | Hard | | | | |
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| 42 | 39. Combination Sum | Backtracking | Backtracking / DFS | Medium | | | | |
| 43 | 79. Word Search | Backtracking | Backtracking / DFS | Medium | | | | |
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| 44 | 208. Implement Trie (Prefix Tree) | Tries | Tries / DFS | Medium | | | | |
| 45 | 211. Design Add and Search Words Data Structure | Tries | Tries / DFS | Medium | | | | |
| 46 | 212. Word Search II | Tries | Tries / DFS | Hard | | | | |
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| 47 | 295. Find Median from Data Stream | Heap | Priority Queue | Hard | | | | |
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| 48 | 200. Number of Islands | Graphs | DFS / BFS / Union Find | Medium | | | | |
| 49 | 133. Clone Graph | Graphs | DFS / BFS / Union Find | Medium | | | | |
| 50 | 417. Pacific Atlantic Water Flow | Graphs | DFS / BFS / Union Find | Medium | | | | |
| 51 | 261. Graph Valid Tree | Graphs | DFS / BFS / Union Find | Medium | | | | |
| 52 | 323. Number of Connected Components in an Undirected Graph | Graphs | DFS / BFS / Union Find | Medium | | | | |
| 53 | 207. Course Schedule | Graphs | DFS / BFS / Union Find | Medium | | | | |
| 54 | 269. Alien Dictionary | Graphs | DFS / BFS / Union Find | Hard | | | | |
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| 55 | 509. Fibonacci Number | Dynamic Programming | Memoization / Tabulation | Easy | | | | |
| 56 | 322. Coin Change | Dynamic Programming | Memoization / Tabulation | Medium | | | | |
| 57 | 70. Climbing Stairs | Dynamic Programming | Memoization / Tabulation | Easy | | | | |
| 58 | 198. House Robber | Dynamic Programming | Memoization / Tabulation | Medium | | | | |
| 59 | 213. House Robber II | Dynamic Programming | Memoization / Tabulation | Medium | | | | |
| 60 | 647. Palindromic Substrings | Dynamic Programming | Memoization / Tabulation | Medium | | | | |
| 61 | 5. Longest Palindromic Substring | Dynamic Programming | Memoization / Tabulation | Medium | | | | |
| 62 | 152. Maximum Product Subarray | Dynamic Programming | Memoization / Tabulation | Medium | | | | |
| 63 | 91. Decode Ways | Dynamic Programming | Memoization / Tabulation | Medium | | | | |
| 64 | 139. Word Break | Dynamic Programming | Memoization / Tabulation | Medium | | | | |
| 65 | 300. Longest Increasing Subsequence | Dynamic Programming | Memoization / Tabulation | Medium | | | | |
| 66 | 1143. Longest Common Subsequence | Dynamic Programming | Memoization / Tabulation | Medium | | | | |
| 67 | 62. Unique Paths | Dynamic Programming | Memoization / Tabulation | Medium | | | | |
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| 68 | 881. Boats to Save People | Greedy | Greedy Algorithm | Medium | | | | |
| 69 | 53. Maximum Subarray | Greedy | Greedy Algorithm | Medium | | | | |
| 70 | 55. Jump Game | Greedy | Greedy Algorithm | Medium | | | | |
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| 71 | 56. Merge Intervals | Intervals | Merge Intervals | Medium | | | | |
| 72 | 57. Insert Interval | Intervals | Merge Intervals | Medium | | | | |
| 73 | 435. Non-overlapping Intervals | Intervals | Merge Intervals | Medium | | | | |
| 74 | 252. Meeting Rooms | Intervals | Merge Intervals | Easy | | | | |
| 75 | 253. Meeting Rooms II | Intervals | Merge Intervals | Medium | | | | |
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| 76 | 48. Rotate Image | Math & Geometry | Matrix / Math | Medium | | | | |
| 77 | 54. Spiral Matrix | Math & Geometry | Matrix / Math | Medium | | | | |
| 78 | 73. Set Matrix Zeroes | Math & Geometry | Matrix / Math | Medium | | | | |
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| 79 | 338. Counting Bits | Binary | Bit Manipulation | Easy | | | | |
| 80 | 268. Missing Number | Binary | Bit Manipulation | Easy | | | | |
| 81 | 191. Number of 1 Bits | Binary | Bit Manipulation | Easy | | | | |
| 82 | 190. Reverse Bits | Binary | Bit Manipulation | Easy | | | | |
| 83 | 371. Sum of Two Integers | Binary | Bit Manipulation | Medium | | | | |