| Best Time to Buy and Sell Stock↗ | easy | ArraySliding Window |
| Climbing Stairs↗ | easy | Dynamic Programming |
| Contains Duplicate↗ | easy | ArrayHashing |
| Counting Bits↗ | easy | Bit Manipulation |
| Invert Binary Tree↗ | easy | Trees |
| Linked List Cycle↗ | easy | Linked List |
| Lowest Common Ancestor of a Binary Search Tree↗ | easy | Binary Search TreeTrees |
| Maximum Depth of Binary Tree↗ | easy | Trees |
| Meeting Rooms↗ | easy | ArrayIntervals |
| Merge Two Sorted Lists↗ | easy | Linked List |
| Missing Number↗ | easy | Bit Manipulation |
| Number of 1 Bits↗ | easy | Bit Manipulation |
| Reverse Bits↗ | easy | Bit Manipulation |
| Reverse Linked List↗ | easy | Linked List |
| Same Tree↗ | easy | Trees |
| Subtree of Another Tree↗ | easy | Trees |
| Two Sum↗ | easy | ArrayHashing |
| Valid Anagram↗ | easy | StringHashing |
| Valid Palindrome↗ | easy | StringTwo Pointers |
| Valid Parentheses↗ | easy | ArrayStack |
| 3Sum↗ | medium | ArrayTwo Pointers |
| Binary Tree Level Order Traversal↗ | medium | Trees |
| Clone Graph↗ | medium | Graphs |
| Coin Change↗ | medium | Dynamic Programming |
| Combination Sum↗ | medium | ArrayBacktracking |
| Construct Binary Tree from Preorder and Inorder Traversal↗ | medium | Trees |
| Container With Most Water↗ | medium | ArrayTwo Pointers |
| Course Schedule↗ | medium | Graphs |
| Decode Ways↗ | medium | Dynamic Programming |
| Design Add and Search Words Data Structure↗ | medium | Tries |
| Encode and Decode Strings↗ | medium | Array |
| Find Minimum in Rotated Sorted Array↗ | medium | Binary Search |
| Graph Valid Tree↗ | medium | Graphs |
| Group Anagrams↗ | medium | StringHashing |
| House Robber↗ | medium | Dynamic Programming |
| House Robber II↗ | medium | Dynamic Programming |
| Implement Trie (Prefix Tree)↗ | medium | Tries |
| Insert Interval↗ | medium | ArrayIntervals |
| Jump Game↗ | medium | Greedy |
| Kth Smallest Element in a BST↗ | medium | Binary Search TreeTrees |
| Longest Common Subsequence↗ | medium | Dynamic Programming2-D Dynamic Programming |
| Longest Consecutive Sequence↗ | medium | ArrayHashing |
| Longest Increasing Subsequence↗ | medium | Dynamic Programming |
| Longest Palindromic Substring↗ | medium | StringDynamic Programming |
| Longest Repeating Character Replacement↗ | medium | StringSliding Window |
| Longest Substring Without Repeating Characters↗ | medium | StringSliding Window |
| Maximum Product Subarray↗ | medium | Dynamic Programming |
| Maximum Subarray↗ | medium | Dynamic ProgrammingGreedy |
| Meeting Rooms II↗ | medium | Intervals |
| Merge Intervals↗ | medium | ArrayIntervals |
| Non-overlapping Intervals↗ | medium | IntervalsGreedy |
| Number of Connected Components in an Undirected Graph↗ | medium | Graphs |
| Number of Islands↗ | medium | Graphs |
| Pacific Atlantic Water Flow↗ | medium | Graphs |
| Palindromic Substrings↗ | medium | Dynamic Programming |
| Product of Array Except Self↗ | medium | ArrayHashing |
| Remove Nth Node From End of List↗ | medium | Linked List |
| Reorder List↗ | medium | Linked List |
| Rotate Image↗ | medium | MatrixMath & Geometry |
| Search in Rotated Sorted Array↗ | medium | Binary Search |
| Set Matrix Zeroes↗ | medium | MatrixMath & Geometry |
| Spiral Matrix↗ | medium | MatrixMath & Geometry |
| Sum of Two Integers↗ | medium | Bit Manipulation |
| Top K Frequent Elements↗ | medium | HeapHashing |
| Unique Paths↗ | medium | Dynamic Programming2-D Dynamic Programming |
| Validate Binary Search Tree↗ | medium | Binary Search TreeTrees |
| Word Break↗ | medium | Dynamic Programming |
| Word Search↗ | medium | GraphsBacktracking |
| Alien Dictionary↗ | hard | GraphsAdvanced Graphs |
| Binary Tree Maximum Path Sum↗ | hard | Trees |
| Find Median from Data Stream↗ | hard | Heap |
| Merge k Sorted Lists↗ | hard | HeapLinked List |
| Minimum Window Substring↗ | hard | StringSliding Window |
| Serialize and Deserialize Binary Tree↗ | hard | Trees |
| Word Search II↗ | hard | Tries |