| 4. Median of Two Sorted Arrays | Solution | Solve | Hard | | |
| 10. Regular Expression Matching | Solution | Solve | Hard | | |
| 23. Merge k Sorted Lists | Solution | Solve | Hard | | |
| 32. Longest Valid Parentheses | 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 | | |
| 115. Distinct Subsequences | Solution | Solve | Hard | | |
| 124. Binary Tree Maximum Path Sum | Solution | Solve | Hard | | |
| 127. Word Ladder | Solution | Solve | Hard | | |
| 135. Candy | Solution | Solve | Hard | | |
| 140. Word Break II | Solution | Solve | Hard | | |
| 212. Word Search II | 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 | | |
| 301. Remove Invalid Parentheses | Solution | Solve | Hard | | |
| 321. Create Maximum Number | Solution | Solve | Hard | | |
| 327. Count of Range Sum | Solution | Solve | Hard | | |
| 403. Frog Jump | Solution | Solve | Hard | | |
| 407. Trapping Rain Water II | Solution | Solve | Hard | | |
| 410. Split Array Largest Sum | Solution | Solve | Hard | | |
| 460. LFU Cache | Solution | Solve | Hard | | |
| 588. Design In-Memory File System | Solution | Solve | Hard | | |
| 716. Max Stack | Solution | Solve | Hard | | |
| 772. Basic Calculator III | Solution | Solve | Hard | | |
| 815. Bus Routes | Solution | Solve | Hard | | |
| 827. Making A Large Island | Solution | Solve | Hard | | |
| 829. Consecutive Numbers Sum | Solution | Solve | Hard | | |
| 920. Number of Music Playlists | Solution | Solve | Hard | | |
| 968. Binary Tree Cameras | Solution | Solve | Hard | | |
| 987. Vertical Order Traversal of a Binary Tree | Solution | Solve | Hard | | |
| 992. Subarrays with K Different Integers | Solution | Solve | Hard | | |
| 1095. Find in Mountain Array | Solution | Solve | Hard | | |
| 1235. Maximum Profit in Job Scheduling | Solution | Solve | Hard | | |
| 1293. Shortest Path in a Grid with Obstacles Elimination | Solution | Solve | Hard | | |
| 1312. Minimum Insertion Steps to Make a String Palindrome | Solution | Solve | Hard | | |
| 1526. Minimum Number of Increments on Subarrays to Form a Target Array | Solution | Solve | Hard | | |
| 1537. Get the Maximum Score | Solution | Solve | Hard | | |
| 1547. Minimum Cost to Cut a Stick | Solution | Solve | Hard | | |
| 1611. Minimum One Bit Operations to Make Integers Zero | Solution | Solve | Hard | | |
| 1944. Number of Visible People in a Queue | Solution | Solve | Hard | | |
