| All O`one Data Structure ↗ | Hard | Hash Table, Linked List, Design | |
| Max Consecutive Ones III ↗ | Medium | Array, Binary Search, Sliding Window | |
| Valid Parentheses ↗ | Easy | String, Stack | |
| Word Ladder ↗ | Hard | Hash Table, String, Breadth-First Search | |
| Number of Islands ↗ | Medium | Array, Depth-First Search, Breadth-First Search | |
| Pow(x, n) ↗ | Medium | Math, Recursion | |
| Insert Delete GetRandom O(1) ↗ | Medium | Array, Hash Table, Math | |
| Find the Celebrity ↗ | Medium | Two Pointers, Graph Theory, Interactive | |
| Maximum Subarray ↗ | Medium | Array, Divide and Conquer, Dynamic Programming | |
| Can Place Flowers ↗ | Easy | Array, Greedy | |
| Exclusive Time of Functions ↗ | Medium | Array, Stack | |
| Sort Transformed Array ↗ | Medium | Array, Math, Two Pointers | |
| Search in Rotated Sorted Array ↗ | Medium | Array, Binary Search | |
| Letter Combinations of a Phone Number ↗ | Medium | Hash Table, String, Backtracking | |
| Paint House ↗ | Medium | Array, Dynamic Programming | |
| Longest Palindromic Subsequence ↗ | Medium | String, Dynamic Programming | |
| Partition to K Equal Sum Subsets ↗ | Medium | Array, Dynamic Programming, Backtracking | |
| Kth Largest Element in an Array ↗ | Medium | Array, Divide and Conquer, Sorting | |
| Minimum Window Substring ↗ | Hard | Hash Table, String, Sliding Window | |
| Find K Pairs with Smallest Sums ↗ | Medium | Array, Heap (Priority Queue) | |
| Sqrt(x) ↗ | Easy | Math, Binary Search | |
| Find First and Last Position of Element in Sorted Array ↗ | Medium | Array, Binary Search | |
| Maximum Product Subarray ↗ | Medium | Array, Dynamic Programming | |
| Serialize and Deserialize Binary Tree ↗ | Hard | String, Tree, Depth-First Search | |
| Max Area of Island ↗ | Medium | Array, Depth-First Search, Breadth-First Search | |
| Longest Valid Parentheses ↗ | Hard | String, Dynamic Programming, Stack | |
| Find K Closest Elements ↗ | Medium | Array, Two Pointers, Binary Search | |
| Accounts Merge ↗ | Medium | Array, Hash Table, String | |
| Lowest Common Ancestor of a Binary Search Tree ↗ | Medium | Tree, Depth-First Search, Binary Search Tree | |
| Bulb Switcher ↗ | Medium | Math, Brainteaser | |
| Flatten Nested List Iterator ↗ | Medium | Stack, Tree, Depth-First Search | |
| Edit Distance ↗ | Medium | String, Dynamic Programming | |
| Maximum Depth of Binary Tree ↗ | Easy | Tree, Depth-First Search, Breadth-First Search | |
| Word Ladder II ↗ | Hard | Hash Table, String, Backtracking | |
| Symmetric Tree ↗ | Easy | Tree, Depth-First Search, Breadth-First Search | |
| LRU Cache ↗ | Medium | Hash Table, Linked List, Design | |
| Intersection of Two Linked Lists ↗ | Easy | Hash Table, Linked List, Two Pointers | |
| Rotate List ↗ | Medium | Linked List, Two Pointers | |
| Valid Parenthesis String ↗ | Medium | String, Dynamic Programming, Stack | |
| Repeated DNA Sequences ↗ | Medium | Hash Table, String, Bit Manipulation | |