| 001 | Two Sum | Easy | Java | 2种方法：暴力 和 HashMap |
| 002 | Add Two Numbers | Medium | Java | 2种方法：模拟 和 递归 |
| 003 | Longest Substring Without Repeating Characters | Medium | Java | |
| 004 | Median of Two Sorted Arrays | Hard | Java | 4种方法：合并数组，暴力法，二分搜索，划分数组 |
| 005 | Longest Palindromic Substring | Medium | Java | |
| 010 | Regular Expression Matching | Hard | Java | |
| 011 | Container With Most Water | Medium | Java | 2 Approaches: BF and Two Pointers with Image Explaination |
| 015 | 3Sum | Medium | Java | 3种方法：暴力，Hash，双指针 |
| 017 | Letter Combinations of a Phone Number | Medium | Java | 4 Approaches: BF 4 Loops, Backtracking, BFS, Queue with Image Explaination |
| 019 | Remove Nth Node From End of List | Easy | Java | |
| 020 | Valid Parentheses | Easy | Java | |
| 021 | Merge Two Sorted Lists | Easy | Java | |
| 022 | Generate Parentheses | Medium | Java | 2种方法：暴力法 和 回溯法 |
| 023 | Merge k Sorted Lists | Hard | Java | |
| 024 | Swap Nodes in Pairs | Medium | Java | |
| 025 | Reverse Nodes in k-Group | Hard | Java | |
| 031 | Next Permutation | Medium | Java | Two Pointers Solution with Detailed Explanation and Code Commented |
| 032 | Longest Valid Parentheses | Hard | Java | |
| 033 | Search in Rotated Sorted Array | Medium | Java | |
| 034 | Search for a Range | Medium | Java | |
| 035 | Search Insert Position | Medium | Java | |
| 039 | Combination Sum | Medium | Java | |
| 042 | Trapping Rain Water | Hard | Java | |
| 045 | Jump Game II | Medium | Java | |
| 046 | Permutations | Medium | Java | |
| 048 | Rotate Image | Medium | Java | |
| 049 | Group Anagrams | Medium | Java | |
| 053 | Maximum Subarray | Medium | Java | |
| 055 | Jump Game | Medium | Java | |
| 056 | Merge Intervals | Medium | Java | |
| 062 | Unique Paths | Medium | Java | |
| 064 | Minimum Path Sum | Medium | Java | |
| 070 | Climbing Stairs | Easy | Java | |
| 072 | Edit Distance | Hard | Java | |
| 075 | Sort Colors | Medium | Java | |
| 076 | Minimum Window Substring | Hard | Java | |
| 078 | Subsets | Medium | Java | |
| 079 | Word Search | Medium | Java | |
| 084 | Largest Rectangle in Histogram | Hard | Java | |
| 085 | Maximal Rectangle | Hard | Java | |
| 094 | Binary Tree Inorder Traversal | Medium | Java | |
| 096 | Unique Binary Search Trees | Medium | Java | |
| 098 | Validate Binary Search Tree | Medium | Java | |
| 101 | Symmetric Tree | Easy | Java | |
| 102 | Binary Tree Level Order Traversal | Easy | Java | |
| 104 | Maximum Depth of Binary Tree | Easy | Java | |
| 105 | Construct Binary Tree from Preorder and Inorder Traversal | Medium | Java | |
| 114 | Flatten Binary Tree to Linked List | Medium | Java | |
| 121 | Best Time to Buy and Sell Stock | Easy | Java | |
| 128 | Longest Consecutive Sequence | Hard | Java | |
| 136 | Single Number | Easy | Java | |
| 139 | Word Break | Medium | Java | |
| 141 | Linked List Cycle | Easy | Java | |
| 142 | Linked List Cycle II | Medium | Java | |
| 146 | LRU Cache | Hard | Java | |
| 148 | Sort List | Medium | Java | |
| 152 | Maximum Product Subarray | Medium | Java | |
| 155 | Min Stack | Easy | Java | 3种方法：辅助栈，栈，链表 |
| 160 | Intersection of Two Linked Lists | Easy | Java | |
| 169 | Majority Element | Easy | Java | |
| 198 | House Robber | Easy | Java | |
| 200 | Number of Islands | Medium | Java | |
| 206 | Reverse Linked List | Easy | Java | |
| 207 | Course Schedule | Medium | Java | |
| 208 | Implement Trie (Prefix Tree) | Medium | Java | |
| 210 | Course Schedule II | Medium | Java | |
| 215 | Kth Largest Element in an Array | Medium | Java | |
| 221 | Maximal Square | Medium | Java | |
| 226 | Invert Binary Tree | Easy | Java | |
| 230 | Kth Smallest Element in a BST | Medium | Java | |
| 234 | Palindrome Linked List | Easy | Java | |
| 238 | Product of Array Except Self | Medium | Java | |
| 239 | Sliding Window Maximum | Hard | Java | |
| 240 | Search a 2D Matrix II | Medium | Java | |
| 253 | Meeting Rooms II | Medium | 没权限 | |
| 279 | Perfect Squares | Medium | Java | |
| 283 | Move Zeroes | Easy | Java | |
| 287 | Find the Duplicate Number | Medium | Java | 9 Approaches: Count, Hash, Sort, Binary Search, Bit, Fast Slow Pointers |
| 297 | Serialize and Deserialize Binary Tree | Hard | Java | |
| 300 | Longest Increasing Subsequence | Medium | Java | |
| 301 | Remove Invalid Parentheses | Hard | Java | |
| 309 | Best Time to Buy and Sell Stock with Cooldown | Medium | Java | |
| 312 | Burst Balloons | Hard | Java | |
| 322 | Coin Change | Medium | Java | |
| 328 | Odd Even Linked List | Medium | Java | |
| 337 | House Robber III | Medium | Java | |
| 338 | Counting Bits | Medium | Java | |
| 347 | Top K Frequent Elements | Medium | Java | |
| 394 | Decode String | Medium | Java | |
| 399 | Evaluate Division | Medium | Java | |
| 406 | Queue Reconstruction by Height | Medium | Java | |
| 416 | Partition Equal Subset Sum | Medium | Java | |
| 437 | Path Sum III | Easy | Java | |
| 438 | Find All Anagrams in a String | Easy | Java | 滑动窗口：从HashMap，数组，再到统计字母数量之差 |
| 448 | Find All Numbers Disappeared in an Array | Easy | Java | |
| 461 | Hamming Distance | Easy | Java | |
| 494 | Target Sum | Medium | Java | |
| 538 | Convert BST to Greater Tree | Easy | Java | |
| 543 | Diameter of Binary Tree | Easy | Java | |
| 560 | Subarray Sum Equals K | Medium | Java | |
| 572 | Subtree of Another Tree | Easy | Java | |
| 581 | Shortest Unsorted Continuous Subarray | Easy | Java | |
| 617 | Merge Two Binary Trees | Easy | Java | 4 Approaches: Recursion, Iteration, BFS and DFS |
| 621 | Task Scheduler | Medium | Java | |
| 647 | Palindromic Substrings | Medium | Java | |
| 739 | Daily Temperatures | Medium | Java | |
| 763 | Partition Labels | Medium | Java | Illustration of the Max Position of the Char in the Partition with Easy Detailed Explanation |