| ID | Title && solution | Coefficient of difficulty | remarks |
|---|---|---|---|
| 0001 | Two Sum | Easy | array; lookup table |
| 0002 | Add Two Numbers | Medium | |
| 0003 | Longest Substring Without Repeating Characters | Medium | sliding window |
| 0017 | Letter Combinations of a Phone Number | Medium | tree |
| 0020 | Valid Parentheses | Easy | |
| 0021 | Merge Two Sorted Lists | Easy | |
| 0025 | Reverse Nodes in k-Group | Hard | |
| 0061 | Rotate List | Medium | |
| 0062 | Unique Paths | Medium | recursion; memory search; dynamic programming |
| 0063 | Unique Paths 2 | Medium | recursion; memory search; dynamic programming |
| 0064 | Minimum Path Sum | Medium | dynamic programming; dfs |
| 0067 | add Binary | Easy | |
| 0070 | Climbing Stairs | Easy | dynamic programming |
| 0076 | Minimum Window Substring | Hard | sliding window |
| 0094 | Binary Tree Inorder Traversal | Medium | binary tree |
| 0100 | Same Tree | Easy | binary tree |
| 0101 | Symmetric Tree | Easy | stack; recursion; iterative |
| 0107 | Binary Tree Level Order Traversal II | Easy | binary tree |
| 0111 | Minimum Depth of Binary Tree | Easy | binary tree |
| 0112 | Path Sum | Easy | binary tree |
| 0120 | Triangle | Medium | dynamic programming; dfs |
| 0167 | Two Sum II - Input array is sorted | Easy | 对撞指针(双索引) |
| 0198 | House Robber | Easy | memory search; dynamic programming |
| 0209 | Minimum Size Subarray Sum | Medium | sliding window |
| 0226 | Invert Binary Tree | Easy | recursion; binary tree |
| 0283 | Move Zeroes(solution1) Move Zeroes(solution2) |
Easy | array |
| 0300 | Longest Increasing Subsequence | Medium | dp |
| 0343 | Integer Break | Medium | recursion; memory search; dynamic programming |
| 0349 | Intersection of Two Arrays | Easy | set |
| 0350 | Intersection of Two Arrays II | Easy | map |
| 0376 | Wiggle Subsequence | Medium | dp |
| 0392 | Is Subsequence | Medium | greedy algorithm |
| 0416 | Partition Equal Subset Sum | Medium | dp; 0-1 knapsack problem |
| 0435 | Non-overlapping Intervals(dp solution) Non-overlapping Intervals(greedy solution) |
Medium | dp; 0-1 knapsack problem |
| 0438 | Find All Anagrams in a String | Easy | sliding window |
| 0447 | Number of Boomerangs | Easy | |
| 0454 | 4Sum II | Medium | |
| 0455 | Assign Cookies | Easy | greedy algorithm |
| 0728 | Self Dividing Numbers | Easy | |
| 0747 | Largest Number At Least Twice of Others | Easy |