| 4Sum |
中等 |
| Substring with Concatenation of All Words |
困难 |
| Valid Sudoku |
中等 |
| Sudoku Solver |
困难 |
| Group Anagrams |
中等 |
| Minimum Window Substring |
困难 |
| Maximal Rectangle |
困难 |
| Binary Tree Inorder Traversal |
中等 |
| Single Number |
简单 |
| Copy List with Random Pointer |
中等 |
| Max Points on a Line |
困难 |
| Repeated DNA Sequences |
中等 |
| Palindrome Pairs |
困难 |
| Top K Frequent Elements |
中等 |
| Design Twitter |
中等 |
| Insert Delete GetRandom O(1) |
中等 |
| Insert Delete GetRandom O(1) - Duplicates allowed |
困难 |
| First Unique Character in a String |
简单 |
| Find the Difference |
简单 |
| Longest Palindrome |
简单 |
| Keyboard Row |
简单 |
| Encode and Decode TinyURL |
中等 |
| Find All Anagrams in a String |
简单 |
| Number of Boomerangs |
简单 |
| Sort Characters By Frequency |
中等 |
| 4Sum II |
中等 |
| Island Perimeter |
简单 |
| Most Frequent Subtree Sum |
中等 |
| Contiguous Array |
中等 |
| Brick Wall |
中等 |
| Subarray Sum Equals K |
中等 |
| Distribute Candies |
简单 |
| Longest Harmonious Subsequence |
简单 |
| Find Duplicate File in System |
中等 |
| Minimum Index Sum of Two Lists |
简单 |
| Smallest Range |
困难 |
| Set Mismatch |
简单 |
| Replace Words |
中等 |
| Employee Importance |
简单 |
| Implement Magic Dictionary |
中等 |
| Top K Frequent Words |
中等 |
| Maximum Length of Repeated Subarray |
中等 |
| Longest Word in Dictionary |
简单 |
| Number of Atoms |
困难 |
| Daily Temperatures |
中等 |
| Shortest Completing Word |
中等 |
| Basic Calculator IV |
困难 |
| Jewels and Stones |
简单 |
| Rabbits in Forest |
中等 |
| Subdomain Visit Count |
简单 |
| Fraction to Recurring Decimal |
中等 |
| Contains Duplicate |
简单 |
| Isomorphic Strings |
简单 |
| Count Primes |
简单 |
| Happy Number |
简单 |
| Contains Duplicate II |
简单 |
| Valid Anagram |
简单 |
| H-Index |
中等 |
| Word Pattern |
简单 |
| Bulls and Cows |
中等 |
| Design HashSet |
简单 |
| Design HashMap |
简单 |
| Random Pick with Blacklist |
困难 |
| Two Sum |
简单 |
| Longest Substring Without Repeating Characters |
中等 |
| Intersection of Two Arrays |
简单 |
| Uncommon Words from Two Sentences |
简单 |
| Intersection of Two Arrays II |
简单 |
| Maximum Frequency Stack |
困难 |