| Two Sum ↗ | Easy | Array, Hash Table | |
| Trapping Rain Water ↗ | Hard | Array, Two Pointers, Dynamic Programming | |
| Longest Substring Without Repeating Characters ↗ | Medium | Hash Table, String, Sliding Window | |
| LRU Cache ↗ | Medium | Hash Table, Linked List, Design | |
| Best Time to Buy and Sell Stock ↗ | Easy | Array, Dynamic Programming | |
| Add Two Numbers ↗ | Medium | Linked List, Math, Recursion | |
| 3Sum ↗ | Medium | Array, Two Pointers, Sorting | |
| Number of Islands ↗ | Medium | Array, Depth-First Search, Breadth-First Search | |
| Median of Two Sorted Arrays ↗ | Hard | Array, Binary Search, Divide and Conquer | |
| Longest Palindromic Substring ↗ | Medium | Two Pointers, String, Dynamic Programming | |
| Container With Most Water ↗ | Medium | Array, Two Pointers, Greedy | |
| Merge Intervals ↗ | Medium | Array, Sorting | |
| Koko Eating Bananas ↗ | Medium | Array, Binary Search | |
| Merge k Sorted Lists ↗ | Hard | Linked List, Divide and Conquer, Heap (Priority Queue) | |
| Group Anagrams ↗ | Medium | Array, Hash Table, String | |
| Course Schedule ↗ | Medium | Depth-First Search, Breadth-First Search, Graph Theory | |
| Subarray Sum Equals K ↗ | Medium | Array, Hash Table, Prefix Sum | |
| Rotting Oranges ↗ | Medium | Array, Breadth-First Search, Matrix | |
| Search in Rotated Sorted Array ↗ | Medium | Array, Binary Search | |
| Lowest Common Ancestor of a Binary Tree ↗ | Medium | Tree, Depth-First Search, Binary Tree | |
| Longest Consecutive Sequence ↗ | Medium | Array, Hash Table, Union-Find | |
| Reorganize String ↗ | Medium | Hash Table, String, Greedy | |
| Longest Common Prefix ↗ | Easy | Array, String, Trie | |
| Generate Parentheses ↗ | Medium | String, Dynamic Programming, Backtracking | |
| Palindrome Number ↗ | Easy | Math | |
| Majority Element ↗ | Easy | Array, Hash Table, Divide and Conquer | |
| Maximum Subarray ↗ | Medium | Array, Divide and Conquer, Dynamic Programming | |
| Letter Combinations of a Phone Number ↗ | Medium | Hash Table, String, Backtracking | |
| Fruit Into Baskets ↗ | Medium | Array, Hash Table, Sliding Window | |
| Valid Parentheses ↗ | Easy | String, Stack | |
| Asteroid Collision ↗ | Medium | Array, Stack, Simulation | |
| Merge Two Sorted Lists ↗ | Easy | Linked List, Recursion | |
| House Robber ↗ | Medium | Array, Dynamic Programming | |
| Climbing Stairs ↗ | Easy | Math, Dynamic Programming, Memoization | |
| Sort Colors ↗ | Medium | Array, Two Pointers, Sorting | |
| Concatenation of Array ↗ | Easy | Array, Simulation | |
| Next Permutation ↗ | Medium | Array, Two Pointers | |
| 4Sum ↗ | Medium | Array, Two Pointers, Sorting | |
| Longest Repeating Character Replacement ↗ | Medium | Hash Table, String, Sliding Window | |
| Sqrt(x) ↗ | Easy | Math, Binary Search | |