| 4. Median of Two Sorted Arrays | Solution | Solve | Hard | | |
| 10. Regular Expression Matching | Solution | Solve | Hard | | |
| 23. Merge k Sorted Lists | Solution | Solve | Hard | | |
| 25. Reverse Nodes in k-Group | Solution | Solve | Hard | | |
| 30. Substring with Concatenation of All Words | Solution | Solve | Hard | | |
| 37. Sudoku Solver | Solution | Solve | Hard | | |
| 41. First Missing Positive | Solution | Solve | Hard | | |
| 42. Trapping Rain Water | Solution | Solve | Hard | | |
| 44. Wildcard Matching | Solution | Solve | Hard | | |
| 51. N-Queens | Solution | Solve | Hard | | |
| 68. Text Justification | Solution | Solve | Hard | | |
| 76. Minimum Window Substring | Solution | Solve | Hard | | |
| 84. Largest Rectangle in Histogram | Solution | Solve | Hard | | |
| 85. Maximal Rectangle | Solution | Solve | Hard | | |
| 123. Best Time to Buy and Sell Stock III | Solution | Solve | Hard | | |
| 124. Binary Tree Maximum Path Sum | Solution | Solve | Hard | | |
| 126. Word Ladder II | Solution | Solve | Hard | | |
| 127. Word Ladder | Solution | Solve | Hard | | |
| 149. Max Points on a Line | Solution | Solve | Hard | | |
| 158. Read N Characters Given read4 II - Call Multiple Times | Solution | Solve | Hard | | |
| 188. Best Time to Buy and Sell Stock IV | Solution | Solve | Hard | | |
| 212. Word Search II | Solution | Solve | Hard | | |
| 218. The Skyline Problem | Solution | Solve | Hard | | |
| 224. Basic Calculator | Solution | Solve | Hard | | |
| 239. Sliding Window Maximum | Solution | Solve | Hard | | |
| 269. Alien Dictionary | Solution | Solve | Hard | | |
| 273. Integer to English Words | Solution | Solve | Hard | | |
| 295. Find Median from Data Stream | Solution | Solve | Hard | | |
| 297. Serialize and Deserialize Binary Tree | Solution | Solve | Hard | | |
| 317. Shortest Distance from All Buildings | Solution | Solve | Hard | | |
| 329. Longest Increasing Path in a Matrix | Solution | Solve | Hard | | |
| 332. Reconstruct Itinerary | Solution | Solve | Hard | | |
| 381. Insert Delete GetRandom O(1) - Duplicates allowed | Solution | Solve | Hard | | |
| 460. LFU Cache | Solution | Solve | Hard | | |
| 472. Concatenated Words | Solution | Solve | Hard | | |
| 480. Sliding Window Median | Solution | Solve | Hard | | |
| 493. Reverse Pairs | Solution | Solve | Hard | | |
| 642. Design Search Autocomplete System | Solution | Solve | Hard | | |
| 759. Employee Free Time | Solution | Solve | Hard | | |
| 768. Max Chunks To Make Sorted II | Solution | Solve | Hard | | |
| 839. Similar String Groups | Solution | Solve | Hard | | |
| 843. Guess the Word | Solution | Solve | Hard | | |
| 895. Maximum Frequency Stack | Solution | Solve | Hard | | |
| 996. Number of Squareful Arrays | Solution | Solve | Hard | | |
| 1168. Optimize Water Distribution in a Village | Solution | Solve | Hard | | |
| 1606. Find Servers That Handled Most Number of Requests | Solution | Solve | Hard | | |
| 1675. Minimize Deviation in Array | Solution | Solve | Hard | | |
| 2065. Maximum Path Quality of a Graph | Solution | Solve | Hard | | |
| 2435. Paths in Matrix Whose Sum Is Divisible by K | Solution | Solve | Hard | | |
| 2972. Count the Number of Incremovable Subarrays II | Solution | Solve | Hard | | |
