| 3. Longest Substring Without Repeating Characters | Solution | Solve | Medium | | |
| 5. Longest Palindromic Substring | Solution | Solve | Medium | | |
| 6. Zigzag Conversion | Solution | Solve | Medium | | |
| 7. Reverse Integer | Solution | Solve | Medium | | |
| 11. Container With Most Water | Solution | Solve | Medium | | |
| 12. Integer to Roman | Solution | Solve | Medium | | |
| 15. 3Sum | Solution | Solve | Medium | | |
| 19. Remove Nth Node From End of List | Solution | Solve | Medium | | |
| 22. Generate Parentheses | Solution | Solve | Medium | | |
| 31. Next Permutation | Solution | Solve | Medium | | |
| 33. Search in Rotated Sorted Array | Solution | Solve | Medium | | |
| 36. Valid Sudoku | Solution | Solve | Medium | | |
| 39. Combination Sum | Solution | Solve | Medium | | |
| 40. Combination Sum II | Solution | Solve | Medium | | |
| 49. Group Anagrams | Solution | Solve | Medium | | |
| 50. Pow(x, n) | Solution | Solve | Medium | | |
| 53. Maximum Subarray | Solution | Solve | Medium | | |
| 54. Spiral Matrix | Solution | Solve | Medium | | |
| 55. Jump Game | Solution | Solve | Medium | | |
| 56. Merge Intervals | Solution | Solve | Medium | | |
| 57. Insert Interval | Solution | Solve | Medium | | |
| 72. Edit Distance | Solution | Solve | Medium | | |
| 73. Set Matrix Zeroes | Solution | Solve | Medium | | |
| 74. Search a 2D Matrix | Solution | Solve | Medium | | |
| 75. Sort Colors | Solution | Solve | Medium | | |
| 78. Subsets | Solution | Solve | Medium | | |
| 79. Word Search | Solution | Solve | Medium | | |
| 81. Search in Rotated Sorted Array II | Solution | Solve | Medium | | |
| 90. Subsets II | Solution | Solve | Medium | | |
| 91. Decode Ways | Solution | Solve | Medium | | |
| 92. Reverse Linked List II | Solution | Solve | Medium | | |
| 103. Binary Tree Zigzag Level Order Traversal | Solution | Solve | Medium | | |
| 106. Construct Binary Tree from Inorder and Postorder Traversal | Solution | Solve | Medium | | |
| 116. Populating Next Right Pointers in Each Node | Solution | Solve | Medium | | |
| 120. Triangle | Solution | Solve | Medium | | |
| 128. Longest Consecutive Sequence | Solution | Solve | Medium | | |
| 138. Copy List with Random Pointer | Solution | Solve | Medium | | |
| 139. Word Break | Solution | Solve | Medium | | |
| 146. LRU Cache | Solution | Solve | Medium | | |
| 152. Maximum Product Subarray | Solution | Solve | Medium | | |
| 153. Find Minimum in Rotated Sorted Array | Solution | Solve | Medium | | |
| 155. Min Stack | Solution | Solve | Medium | | |
| 162. Find Peak Element | Solution | Solve | Medium | | |
| 189. Rotate Array | Solution | Solve | Medium | | |
| 198. House Robber | Solution | Solve | Medium | | |
| 199. Binary Tree Right Side View | Solution | Solve | Medium | | |
| 200. Number of Islands | Solution | Solve | Medium | | |
| 207. Course Schedule | Solution | Solve | Medium | | |
| 210. Course Schedule II | Solution | Solve | Medium | | |
| 215. Kth Largest Element in an Array | Solution | Solve | Medium | | |
