| 2. Add Two Numbers | Solution | Solve | Medium | | |
| 3. Longest Substring Without Repeating Characters | Solution | Solve | Medium | | |
| 5. Longest Palindromic Substring | Solution | Solve | Medium | | |
| 7. Reverse Integer | Solution | Solve | Medium | | |
| 11. Container With Most Water | Solution | Solve | Medium | | |
| 17. Letter Combinations of a Phone Number | Solution | Solve | Medium | | |
| 18. 4Sum | Solution | Solve | Medium | | |
| 19. Remove Nth Node From End of List | Solution | Solve | Medium | | |
| 22. Generate Parentheses | Solution | Solve | Medium | | |
| 24. Swap Nodes in Pairs | Solution | Solve | Medium | | |
| 33. Search in Rotated Sorted Array | Solution | Solve | Medium | | |
| 49. Group Anagrams | Solution | Solve | Medium | | |
| 53. Maximum Subarray | Solution | Solve | Medium | | |
| 56. Merge Intervals | Solution | Solve | Medium | | |
| 71. Simplify Path | Solution | Solve | Medium | | |
| 74. Search a 2D Matrix | Solution | Solve | Medium | | |
| 98. Validate Binary Search Tree | Solution | Solve | Medium | | |
| 102. Binary Tree Level Order Traversal | Solution | Solve | Medium | | |
| 103. Binary Tree Zigzag Level Order Traversal | Solution | Solve | Medium | | |
| 146. LRU Cache | Solution | Solve | Medium | | |
| 150. Evaluate Reverse Polish Notation | Solution | Solve | Medium | | |
| 153. Find Minimum in Rotated Sorted Array | Solution | Solve | Medium | | |
| 155. Min Stack | Solution | Solve | Medium | | |
| 161. One Edit Distance | Solution | Solve | Medium | | |
| 167. Two Sum II - Input Array Is Sorted | Solution | Solve | Medium | | |
| 199. Binary Tree Right Side View | Solution | Solve | Medium | | |
| 200. Number of Islands | Solution | Solve | Medium | | |
| 209. Minimum Size Subarray Sum | Solution | Solve | Medium | | |
| 227. Basic Calculator II | Solution | Solve | Medium | | |
| 235. Lowest Common Ancestor of a Binary Search Tree | Solution | Solve | Medium | | |
| 236. Lowest Common Ancestor of a Binary Tree | Solution | Solve | Medium | | |
| 238. Product of Array Except Self | Solution | Solve | Medium | | |
| 279. Perfect Squares | Solution | Solve | Medium | | |
| 300. Longest Increasing Subsequence | Solution | Solve | Medium | | |
| 322. Coin Change | Solution | Solve | Medium | | |
| 340. Longest Substring with At Most K Distinct Characters | Solution | Solve | Medium | | |
| 341. Flatten Nested List Iterator | Solution | Solve | Medium | | |
| 347. Top K Frequent Elements | Solution | Solve | Medium | | |
| 356. Line Reflection | Solution | Solve | Medium | | |
| 362. Design Hit Counter | Solution | Solve | Medium | | |
| 380. Insert Delete GetRandom O(1) | Solution | Solve | Medium | | |
| 395. Longest Substring with At Least K Repeating Characters | Solution | Solve | Medium | | |
| 424. Longest Repeating Character Replacement | Solution | Solve | Medium | | |
| 438. Find All Anagrams in a String | Solution | Solve | Medium | | |
| 443. String Compression | Solution | Solve | Medium | | |
| 470. Implement Rand10() Using Rand7() | Solution | Solve | Medium | | |
| 487. Max Consecutive Ones II | Solution | Solve | Medium | | |
| 523. Continuous Subarray Sum | Solution | Solve | Medium | | |
| 560. Subarray Sum Equals K | Solution | Solve | Medium | | |
| 567. Permutation in String | Solution | Solve | Medium | | |
