| 1. Two Sum | | | Solve | Easy | | |
| 2. Add Two Numbers | | | Solve | Medium | | |
| 3. Longest Substring Without Repeating Characters | | | Solve | Medium | | |
| 5. Longest Palindromic Substring | | | Solve | Medium | | |
| 7. Reverse Integer | | | Solve | Medium | | |
| 13. Roman to Integer | | | Solve | Easy | | |
| 15. 3Sum | | | Solve | Medium | | |
| 17. Letter Combinations of a Phone Number | | | Solve | Medium | | |
| 20. Valid Parentheses | | | Solve | Easy | | |
| 21. Merge Two Sorted Lists | | | Solve | Easy | | |
| 22. Generate Parentheses | | | Solve | Medium | | |
| 23. Merge k Sorted Lists | | | Solve | Hard | | |
| 30. Substring with Concatenation of All Words | | | Solve | Hard | | |
| 32. Longest Valid Parentheses | | | Solve | Hard | | |
| 33. Search in Rotated Sorted Array | | | Solve | Medium | | |
| 34. Find First and Last Position of Element in Sorted Array | | | Solve | Medium | | |
| 40. Combination Sum II | | | Solve | Medium | | |
| 42. Trapping Rain Water | | | Solve | Hard | | |
| 46. Permutations | | | Solve | Medium | | |
| 49. Group Anagrams | | | Solve | Medium | | |
| 50. Pow(x, n) | | | Solve | Medium | | |
| 53. Maximum Subarray | | | Solve | Medium | | |
| 54. Spiral Matrix | | | Solve | Medium | | |
| 56. Merge Intervals | | | Solve | Medium | | |
| 62. Unique Paths | | | Solve | Medium | | |
| 63. Unique Paths II | | | Solve | Medium | | |
| 64. Minimum Path Sum | | | Solve | Medium | | |
| 68. Text Justification | | | Solve | Hard | | |
| 74. Search a 2D Matrix | | | Solve | Medium | | |
| 76. Minimum Window Substring | | | Solve | Hard | | |
| 88. Merge Sorted Array | | | Solve | Easy | | |
| 92. Reverse Linked List II | | | Solve | Medium | | |
| 94. Binary Tree Inorder Traversal | | | Solve | Easy | | |
| 98. Validate Binary Search Tree | | | Solve | Medium | | |
| 102. Binary Tree Level Order Traversal | | | Solve | Medium | | |
| 103. Binary Tree Zigzag Level Order Traversal | | | Solve | Medium | | |
| 108. Convert Sorted Array to Binary Search Tree | | | Solve | Easy | | |
| 112. Path Sum | | | Solve | Easy | | |
| 113. Path Sum II | | | Solve | Medium | | |
| 116. Populating Next Right Pointers in Each Node | | | Solve | Medium | | |
| 121. Best Time to Buy and Sell Stock | | | Solve | Easy | | |
| 122. Best Time to Buy and Sell Stock II | | | Solve | Medium | | |
| 124. Binary Tree Maximum Path Sum | | | Solve | Hard | | |
| 139. Word Break | | | Solve | Medium | | |
| 141. Linked List Cycle | | | Solve | Easy | 42gearMobilitySystems+131 | |
| 146. LRU Cache | | | Solve | Medium | | |
| 149. Max Points on a Line | | | Solve | Hard | | |
| 150. Evaluate Reverse Polish Notation | | | Solve | Medium | | |
| 153. Find Minimum in Rotated Sorted Array | | | Solve | Medium | | |
| 155. Min Stack | | | Solve | Medium | | |