686 problems · Solve with AI-powered hints & explanations
| # | Title | Difficulty |
|---|---|---|
| 4 | Median of Two Sorted Arrays | Hard |
| 10 | Regular Expression Matching | Hard |
| 23 | Merge k Sorted Lists |
Page 1 of 14
| Hard |
| 25 | Reverse Nodes in k-Group | Hard |
| 30 | Substring with Concatenation of All Words | Hard |
| 32 | Longest Valid Parentheses | Hard |
| 37 | Sudoku Solver | Hard |
| 41 | First Missing Positive | Hard |
| 42 | Trapping Rain Water | Hard |
| 44 | Wildcard Matching | Hard |
| 51 | N-Queens | Hard |
| 52 | N-Queens II | Hard |
| 60 | Permutation Sequence | Hard |
| 65 | Valid Number | Hard |
| 68 | Text Justification | Hard |
| 76 | Minimum Window Substring | Hard |
| 84 | Largest Rectangle in Histogram | Hard |
| 85 | Maximal Rectangle | Hard |
| 87 | Scramble String | Hard |
| 115 | Distinct Subsequences | Hard |
| 123 | Best Time to Buy and Sell Stock III | Hard |
| 124 | Binary Tree Maximum Path Sum | Hard |
| 126 | Word Ladder II | Hard |
| 127 | Word Ladder | Hard |
| 132 | Palindrome Partitioning II | Hard |
| 135 | Candy | Hard |
| 140 | Word Break II | Hard |
| 149 | Max Points on a Line | Hard |
| 154 | Find Minimum in Rotated Sorted Array II | Hard |
| 174 | Dungeon Game | Hard |
| 185 | Department Top Three Salaries | Hard |
| 188 | Best Time to Buy and Sell Stock IV | Hard |
| 212 | Word Search II | Hard |
| 214 | Shortest Palindrome | Hard |
| 218 | The Skyline Problem | Hard |
| 220 | Contains Duplicate III | Hard |
| 224 | Basic Calculator | Hard |
| 233 | Number of Digit One | Hard |
| 239 | Sliding Window Maximum | Hard |
| 262 | Trips and Users | Hard |
| 273 | Integer to English Words | Hard |
| 282 | Expression Add Operators | Hard |
| 295 | Find Median from Data Stream | Hard |
| 297 | Serialize and Deserialize Binary Tree | Hard |
| 301 | Remove Invalid Parentheses | Hard |
| 312 | Burst Balloons | Hard |
| 315 | Count of Smaller Numbers After Self | Hard |
| 321 | Create Maximum Number | Hard |
| 327 | Count of Range Sum | Hard |
| 329 | Longest Increasing Path in a Matrix | Hard |
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