Meta LeetCode Questions
100 questions all-time · 23 easy · 61 medium · 16 hard
| # | Problem | Difficulty | Frequency | Acceptance |
|---|---|---|---|---|
| 1 | Merge Sorted Array Array, Two Pointers, Sorting | Easy | 88 | 52.9% |
| 2 | Pow(x, n) Math, Recursion | Medium | 87 | 37.0% |
| 3 | Simplify Path String, Stack | Medium | 86 | 47.9% |
| 4 | Merge Intervals Array, Sorting | Medium | 85 | 49.4% |
| 5 | Two Sum Array, Hash Table | Easy | 84 | 55.8% |
| 6 | Next Permutation Array, Two Pointers | Medium | 78 | 43.1% |
| 7 | Merge k Sorted Lists Linked List, Divide and Conquer, Heap (Priority Queue), Merge Sort | Hard | 77 | 56.8% |
| 8 | 3Sum Array, Two Pointers, Sorting | Medium | 77 | 37.1% |
| 9 | Find First and Last Position of Element in Sorted Array Array, Binary Search | Medium | 72 | 46.8% |
| 10 | Valid Parentheses String, Stack | Easy | 71 | 42.3% |
| 11 | Valid Number String | Hard | 70 | 21.6% |
| 12 | Minimum Window Substring Hash Table, String, Sliding Window | Hard | 69 | 45.4% |
| 13 | Longest Common Prefix String, Trie | Easy | 67 | 45.5% |
| 14 | Add Two Numbers Linked List, Math, Recursion | Medium | 65 | 46.2% |
| 15 | Letter Combinations of a Phone Number Hash Table, String, Backtracking | Medium | 64 | 63.9% |
| 16 | Subsets Array, Backtracking, Bit Manipulation | Medium | 64 | 80.9% |
| 17 | Remove Nth Node From End of List Linked List, Two Pointers | Medium | 64 | 49.0% |
| 18 | Longest Substring Without Repeating Characters Hash Table, String, Sliding Window | Medium | 63 | 36.9% |
| 19 | Trapping Rain Water Array, Two Pointers, Dynamic Programming, Stack, Monotonic Stack | Hard | 61 | 65.1% |
| 20 | String to Integer (atoi) String | Medium | 60 | 19.2% |
| 21 | Longest Palindromic Substring Two Pointers, String, Dynamic Programming | Medium | 59 | 35.8% |
| 22 | Remove Duplicates from Sorted Array Array, Two Pointers | Easy | 59 | 60.4% |
| 23 | Median of Two Sorted Arrays Array, Binary Search, Divide and Conquer | Hard | 58 | 43.8% |
| 24 | Palindrome Number Math | Easy | 57 | 59.2% |
| 25 | Search in Rotated Sorted Array Array, Binary Search | Medium | 57 | 42.8% |
| 26 | Roman to Integer Hash Table, Math, String | Easy | 56 | 64.9% |
| 27 | Merge Two Sorted Lists Linked List, Recursion | Easy | 54 | 66.8% |
| 28 | Group Anagrams Array, Hash Table, String, Sorting | Medium | 54 | 70.9% |
| 29 | Count and Say String | Medium | 53 | 60.5% |
| 30 | Climbing Stairs Math, Dynamic Programming, Memoization | Easy | 53 | 53.5% |
| 31 | Maximum Subarray Array, Divide and Conquer, Dynamic Programming | Medium | 52 | 52.1% |
| 32 | Container With Most Water Array, Two Pointers, Greedy | Medium | 52 | 57.8% |
| 33 | Set Matrix Zeroes Array, Hash Table, Matrix | Medium | 51 | 60.7% |
| 34 | Sort Colors Array, Two Pointers, Sorting | Medium | 51 | 67.6% |
| 35 | Add Binary Math, String, Bit Manipulation, Simulation | Easy | 51 | 55.7% |
| 36 | Multiply Strings Math, String, Simulation | Medium | 50 | 42.3% |
| 37 | Reverse Integer Math | Medium | 49 | 30.3% |
| 38 | Word Search Array, String, Backtracking, Depth-First Search, Matrix | Medium | 48 | 45.3% |
| 39 | Plus One Array, Math | Easy | 48 | 47.5% |
| 40 | Generate Parentheses String, Dynamic Programming, Backtracking | Medium | 48 | 77.1% |
| 41 | Rotate Image Array, Math, Matrix | Medium | 47 | 77.9% |
| 42 | Spiral Matrix Array, Matrix, Simulation | Medium | 47 | 53.9% |
| 43 | Regular Expression Matching String, Dynamic Programming, Recursion | Hard | 46 | 29.3% |
| 44 | Insert Interval Array | Medium | 45 | 43.5% |
| 45 | Find the Index of the First Occurrence in a String Two Pointers, String, String Matching | Easy | 45 | 45.0% |
| 46 | Sqrt(x) Math, Binary Search | Easy | 44 | 40.4% |
| 47 | Search a 2D Matrix Array, Binary Search, Matrix | Medium | 43 | 52.3% |
| 48 | Binary Tree Zigzag Level Order Traversal Tree, Breadth-First Search, Binary Tree | Medium | 43 | 61.7% |
| 49 | Divide Two Integers Math, Bit Manipulation | Medium | 43 | 18.4% |
| 50 | Largest Rectangle in Histogram Array, Stack, Monotonic Stack | Hard | 43 | 47.4% |
| 51 | Binary Tree Level Order Traversal Tree, Breadth-First Search, Binary Tree | Medium | 43 | 70.6% |
| 52 | Remove Duplicates from Sorted Array II Array, Two Pointers | Medium | 42 | 62.9% |
| 53 | Unique Paths Math, Dynamic Programming, Combinatorics | Medium | 42 | 65.8% |
| 54 | Remove Element Array, Two Pointers | Easy | 42 | 60.0% |
| 55 | Jump Game Array, Dynamic Programming, Greedy | Medium | 42 | 39.5% |
| 56 | Text Justification Array, String, Simulation | Hard | 41 | 48.1% |
| 57 | Validate Binary Search Tree Tree, Depth-First Search, Binary Search Tree, Binary Tree | Medium | 41 | 34.4% |
| 58 | 3Sum Closest Array, Two Pointers, Sorting | Medium | 40 | 46.9% |
| 59 | Decode Ways String, Dynamic Programming | Medium | 40 | 36.5% |
| 60 | Combination Sum Array, Backtracking | Medium | 40 | 74.7% |
| 61 | Subsets II Array, Backtracking, Bit Manipulation | Medium | 37 | 59.5% |
| 62 | 4Sum Array, Two Pointers, Sorting | Medium | 37 | 38.2% |
| 63 | Maximal Rectangle Array, Dynamic Programming, Stack, Matrix, Monotonic Stack | Hard | 37 | 53.7% |
| 64 | Valid Sudoku Array, Hash Table, Matrix | Medium | 37 | 62.3% |
| 65 | Permutations Array, Backtracking | Medium | 36 | 80.7% |
| 66 | Reverse Nodes in k-Group Linked List, Recursion | Hard | 36 | 63.0% |
| 67 | Zigzag Conversion String | Medium | 36 | 51.6% |
| 68 | First Missing Positive Array, Hash Table | Hard | 35 | 41.1% |
| 69 | Wildcard Matching String, Dynamic Programming, Greedy, Recursion | Hard | 35 | 29.9% |
| 70 | Binary Tree Inorder Traversal Stack, Tree, Depth-First Search, Binary Tree | Easy | 35 | 78.6% |
| 71 | Minimum Depth of Binary Tree Tree, Depth-First Search, Breadth-First Search, Binary Tree | Easy | 35 | 50.7% |
| 72 | Combination Sum II Array, Backtracking | Medium | 35 | 57.7% |
| 73 | Unique Paths II Array, Dynamic Programming, Matrix | Medium | 35 | 43.2% |
| 74 | N-Queens Array, Backtracking | Hard | 34 | 72.8% |
| 75 | Construct Binary Tree from Preorder and Inorder Traversal Array, Hash Table, Divide and Conquer, Tree, Binary Tree | Medium | 34 | 66.8% |
| 76 | Search Insert Position Array, Binary Search | Easy | 34 | 49.0% |
| 77 | Jump Game II Array, Dynamic Programming, Greedy | Medium | 34 | 41.5% |
| 78 | Rotate List Linked List, Two Pointers | Medium | 33 | 39.9% |
| 79 | Search in Rotated Sorted Array II Array, Binary Search | Medium | 33 | 38.9% |
| 80 | Maximum Depth of Binary Tree Tree, Depth-First Search, Breadth-First Search, Binary Tree | Easy | 32 | 77.1% |
| 81 | Reverse Linked List II Linked List | Medium | 32 | 49.6% |
| 82 | Edit Distance String, Dynamic Programming | Medium | 32 | 58.8% |
| 83 | Length of Last Word String | Easy | 32 | 56.3% |
| 84 | Sudoku Solver Array, Hash Table, Backtracking, Matrix | Hard | 31 | 63.9% |
| 85 | Symmetric Tree Tree, Depth-First Search, Breadth-First Search, Binary Tree | Easy | 31 | 59.3% |
| 86 | Convert Sorted List to Binary Search Tree Linked List, Divide and Conquer, Tree, Binary Search Tree, Binary Tree | Medium | 27 | 64.5% |
| 87 | Restore IP Addresses String, Backtracking | Medium | 27 | 53.2% |
| 88 | Longest Valid Parentheses String, Dynamic Programming, Stack | Hard | 27 | 36.3% |
| 89 | Same Tree Tree, Depth-First Search, Breadth-First Search, Binary Tree | Easy | 26 | 65.1% |
| 90 | Integer to Roman Hash Table, Math, String | Medium | 26 | 68.6% |
| 91 | Swap Nodes in Pairs Linked List, Recursion | Medium | 26 | 67.2% |
| 92 | Combinations Backtracking | Medium | 24 | 72.9% |
| 93 | Convert Sorted Array to Binary Search Tree Array, Divide and Conquer, Tree, Binary Search Tree, Binary Tree | Easy | 22 | 74.1% |
| 94 | Minimum Path Sum Array, Dynamic Programming, Matrix | Medium | 22 | 66.5% |
| 95 | Balanced Binary Tree Tree, Depth-First Search, Binary Tree | Easy | 22 | 55.3% |
| 96 | Permutations II Array, Backtracking, Sorting | Medium | 18 | 61.6% |
| 97 | Unique Binary Search Trees II Dynamic Programming, Backtracking, Tree, Binary Search Tree, Binary Tree | Medium | 16 | 60.4% |
| 98 | Substring with Concatenation of All Words Hash Table, String, Sliding Window | Hard | 16 | 33.0% |
| 99 | Spiral Matrix II Array, Matrix, Simulation | Medium | 14 | 73.4% |
| 100 | Binary Tree Level Order Traversal II Tree, Breadth-First Search, Binary Tree | Medium | 8 | 66.0% |
How to read this list
The tabs at the top split the questions by how recently people said they were asked in interviews. "Last 30 Days" is the past month, "Last 3 Months" is the past quarter, and so on. "All Time" is every question on record for this company.
Frequency is a score from 0 to 100 for how often a question showed up in that time window. A higher number means it came up more often, so the list starts with the most common questions first. Acceptance is the share of submissions that pass on LeetCode. Click any question to open it on LeetCode.