2,913 problems · Solve with AI-powered hints & explanations
| # | Title | Difficulty |
|---|---|---|
| 1 | Two Sum | Easy |
| 2 | Add Two Numbers | Medium |
| 3 | Longest Substring Without Repeating Characters |
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| Medium |
| 4 | Median of Two Sorted Arrays | Hard |
| 5 | Longest Palindromic Substring | Medium |
| 6 | Zigzag Conversion | Medium |
| 7 | Reverse Integer | Medium |
| 8 | String to Integer (atoi) | Medium |
| 9 | Palindrome Number | Easy |
| 10 | Regular Expression Matching | Hard |
| 11 | Container With Most Water | Medium |
| 12 | Integer to Roman | Medium |
| 13 | Roman to Integer | Easy |
| 14 | Longest Common Prefix | Easy |
| 15 | 3Sum | Medium |
| 16 | 3Sum Closest | Medium |
| 17 | Letter Combinations of a Phone Number | Medium |
| 18 | 4Sum | Medium |
| 19 | Remove Nth Node From End of List | Medium |
| 20 | Valid Parentheses | Easy |
| 21 | Merge Two Sorted Lists | Easy |
| 22 | Generate Parentheses | Medium |
| 23 | Merge k Sorted Lists | Hard |
| 24 | Swap Nodes in Pairs | Medium |
| 25 | Reverse Nodes in k-Group | Hard |
| 26 | Remove Duplicates from Sorted Array | Easy |
| 27 | Remove Element | Easy |
| 28 | Find the Index of the First Occurrence in a String | Easy |
| 29 | Divide Two Integers | Medium |
| 30 | Substring with Concatenation of All Words | Hard |
| 31 | Next Permutation | Medium |
| 32 | Longest Valid Parentheses | Hard |
| 33 | Search in Rotated Sorted Array | Medium |
| 34 | Find First and Last Position of Element in Sorted Array | Medium |
| 35 | Search Insert Position | Easy |
| 36 | Valid Sudoku | Medium |
| 37 | Sudoku Solver | Hard |
| 38 | Count and Say | Medium |
| 39 | Combination Sum | Medium |
| 40 | Combination Sum II | Medium |
| 41 | First Missing Positive | Hard |
| 42 | Trapping Rain Water | Hard |
| 43 | Multiply Strings | Medium |
| 44 | Wildcard Matching | Hard |
| 45 | Jump Game II | Medium |
| 46 | Permutations | Medium |
| 47 | Permutations II | Medium |
| 48 | Rotate Image | Medium |
| 49 | Group Anagrams | Medium |
| 50 | Pow(x, n) | Medium |
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