Walmart Labs LeetCode Questions
144 questions all-time · 22 easy · 96 medium · 26 hard
| # | Problem | Difficulty | Frequency | Acceptance |
|---|---|---|---|---|
| 1 | Longest Substring Without Repeating Characters Hash Table, String, Sliding Window | Medium | 100 | 0.4% |
| 2 | Number of Islands Array, Depth-First Search, Breadth-First Search, Union-Find, Matrix | Medium | 100 | 0.6% |
| 3 | LRU Cache Hash Table, Linked List, Design, Doubly-Linked List | Medium | 98 | 0.5% |
| 4 | Valid Parentheses String, Stack | Easy | 97 | 0.4% |
| 5 | Two Sum Array, Hash Table | Easy | 93 | 0.6% |
| 6 | Generate Parentheses String, Dynamic Programming, Backtracking | Medium | 91 | 0.8% |
| 7 | Trapping Rain Water Array, Two Pointers, Dynamic Programming, Stack, Monotonic Stack | Hard | 91 | 0.7% |
| 8 | Search in Rotated Sorted Array Array, Binary Search | Medium | 88 | 0.5% |
| 9 | Merge Intervals Array, Sorting | Medium | 88 | 0.5% |
| 10 | Divide Intervals Into Minimum Number of Groups Array, Two Pointers, Greedy, Sorting, Heap (Priority Queue), Prefix Sum | Medium | 88 | 0.6% |
| 11 | Middle of the Linked List Linked List, Two Pointers | Easy | 88 | 0.8% |
| 12 | Number of Ways to Separate Numbers String, Dynamic Programming, Prefix Sum | Hard | 86 | 0.2% |
| 13 | The Winner University Database | Easy | 86 | 0.8% |
| 14 | Count Good Triplets in an Array Array, Binary Search, Divide and Conquer, Binary Indexed Tree, Segment Tree, Merge Sort, Ordered Set | Hard | 86 | 0.7% |
| 15 | Minimum Number of Operations to Make Arrays Similar Array, Greedy, Sorting | Hard | 86 | 0.6% |
| 16 | Minimum Operations to Make Array Equal II Array, Math, Greedy | Medium | 86 | 0.3% |
| 17 | Maximum Number of Tasks You Can Assign Array, Two Pointers, Binary Search, Greedy, Queue, Sorting, Monotonic Queue | Hard | 86 | 0.5% |
| 18 | Count Elements With Maximum Frequency Array, Hash Table, Counting | Easy | 86 | 0.8% |
| 19 | Maximum Length Substring With Two Occurrences Hash Table, String, Sliding Window | Easy | 86 | 0.7% |
| 20 | Circular Permutation in Binary Representation Math, Backtracking, Bit Manipulation | Medium | 86 | 0.7% |
| 21 | Find the N-th Value After K Seconds Array, Math, Simulation, Combinatorics, Prefix Sum | Medium | 86 | 0.5% |
| 22 | XOR Operation in an Array Math, Bit Manipulation | Easy | 86 | 0.9% |
| 23 | Group Anagrams Array, Hash Table, String, Sorting | Medium | 83 | 0.7% |
| 24 | Word Break Array, Hash Table, String, Dynamic Programming, Trie, Memoization | Medium | 83 | 0.5% |
| 25 | Maximum Distance Between Unequal Words in Array I Array, String | Easy | 80 | 0.8% |
| 26 | Best Time to Buy and Sell Stock Array, Dynamic Programming | Easy | 76 | 0.6% |
| 27 | Coin Change Array, Dynamic Programming, Breadth-First Search | Medium | 76 | 0.5% |
| 28 | Longest Palindromic Substring Two Pointers, String, Dynamic Programming | Medium | 72 | 0.4% |
| 29 | Container With Most Water Array, Two Pointers, Greedy | Medium | 72 | 0.6% |
| 30 | Combination Sum Array, Backtracking | Medium | 72 | 0.8% |
| 31 | Sort Colors Array, Two Pointers, Sorting | Medium | 72 | 0.7% |
| 32 | Longest Consecutive Sequence Array, Hash Table, Union-Find | Medium | 72 | 0.5% |
| 33 | Max Stack Linked List, Stack, Design, Doubly-Linked List, Ordered Set | Hard | 72 | 0.5% |
| 34 | Longest Increasing Subsequence Array, Binary Search, Dynamic Programming | Medium | 72 | 0.6% |
| 35 | Advantage Shuffle Array, Two Pointers, Greedy, Sorting | Medium | 72 | 0.5% |
| 36 | Median of Two Sorted Arrays Array, Binary Search, Divide and Conquer | Hard | 67 | 0.5% |
| 37 | 3Sum Array, Two Pointers, Sorting | Medium | 67 | 0.4% |
| 38 | Spiral Matrix Array, Matrix, Simulation | Medium | 67 | 0.6% |
| 39 | Binary Tree Zigzag Level Order Traversal Tree, Breadth-First Search, Binary Tree | Medium | 67 | 0.6% |
| 40 | Kth Largest Element in an Array Array, Divide and Conquer, Sorting, Heap (Priority Queue), Quickselect | Medium | 67 | 0.7% |
| 41 | First Unique Character in a String Hash Table, String, Queue, Counting | Easy | 67 | 0.7% |
| 42 | LFU Cache Hash Table, Linked List, Design, Doubly-Linked List | Hard | 67 | 0.5% |
| 43 | Zigzag Conversion String | Medium | 67 | 0.5% |
| 44 | Find Median from Data Stream Two Pointers, Design, Sorting, Heap (Priority Queue), Data Stream | Hard | 67 | 0.5% |
| 45 | Sort the Matrix Diagonally Array, Sorting, Matrix | Medium | 67 | 0.8% |
| 46 | Longest Common Prefix Array, String, Trie | Easy | 61 | 0.5% |
| 47 | Merge k Sorted Lists Linked List, Divide and Conquer, Heap (Priority Queue), Merge Sort | Hard | 61 | 0.6% |
| 48 | Reverse Nodes in k-Group Linked List, Recursion | Hard | 61 | 0.7% |
| 49 | Valid Sudoku Array, Hash Table, Matrix | Medium | 61 | 0.6% |
| 50 | Maximum Subarray Array, Divide and Conquer, Dynamic Programming | Medium | 61 | 0.5% |
| 51 | Add Binary Math, String, Bit Manipulation, Simulation | Easy | 61 | 0.6% |
| 52 | Binary Tree Right Side View Tree, Depth-First Search, Breadth-First Search, Binary Tree | Medium | 61 | 0.7% |
| 53 | Course Schedule Depth-First Search, Breadth-First Search, Graph Theory, Topological Sort | Medium | 61 | 0.5% |
| 54 | Move Zeroes Array, Two Pointers | Easy | 61 | 0.6% |
| 55 | Top K Frequent Elements Array, Hash Table, Divide and Conquer, Sorting, Heap (Priority Queue), Bucket Sort, Counting, Quickselect | Medium | 61 | 0.7% |
| 56 | Subarray Sum Equals K Array, Hash Table, Prefix Sum | Medium | 61 | 0.5% |
| 57 | Subsets II Array, Backtracking, Bit Manipulation | Medium | 61 | 0.6% |
| 58 | Maximum Sum of Distinct Subarrays With Length K Array, Hash Table, Sliding Window | Medium | 61 | 0.4% |
| 59 | Trapping Rain Water II Array, Breadth-First Search, Heap (Priority Queue), Matrix | Hard | 61 | 0.6% |
| 60 | Integer to Roman Hash Table, Math, String | Medium | 61 | 0.7% |
| 61 | Palindromic Substrings Two Pointers, String, Dynamic Programming | Medium | 61 | 0.7% |
| 62 | Design Hit Counter Array, Binary Search, Design, Queue, Data Stream | Medium | 61 | 0.7% |
| 63 | Rotting Oranges Array, Breadth-First Search, Matrix | Medium | 61 | 0.6% |
| 64 | Diagonal Traverse Array, Matrix, Simulation | Medium | 61 | 0.7% |
| 65 | Construct Binary Tree from Inorder and Postorder Traversal Array, Hash Table, Divide and Conquer, Tree, Binary Tree | Medium | 61 | 0.7% |
| 66 | Permutation in String Hash Table, Two Pointers, String, Sliding Window | Medium | 61 | 0.5% |
| 67 | First Missing Positive Array, Hash Table | Hard | 54 | 0.4% |
| 68 | Search a 2D Matrix Array, Binary Search, Matrix | Medium | 54 | 0.5% |
| 69 | Minimum Window Substring Hash Table, String, Sliding Window | Hard | 54 | 0.5% |
| 70 | Largest Rectangle in Histogram Array, Stack, Monotonic Stack | Hard | 54 | 0.5% |
| 71 | Decode Ways String, Dynamic Programming | Medium | 54 | 0.4% |
| 72 | Min Stack Stack, Design | Medium | 54 | 0.6% |
| 73 | Rotate Array Array, Math, Two Pointers | Medium | 54 | 0.5% |
| 74 | House Robber Array, Dynamic Programming | Medium | 54 | 0.5% |
| 75 | Course Schedule II Depth-First Search, Breadth-First Search, Graph Theory, Topological Sort | Medium | 54 | 0.6% |
| 76 | Wildcard Matching String, Dynamic Programming, Greedy, Recursion | Hard | 54 | 0.3% |
| 77 | Daily Temperatures Array, Stack, Monotonic Stack | Medium | 54 | 0.7% |
| 78 | Jump Game Array, Dynamic Programming, Greedy | Medium | 54 | 0.4% |
| 79 | Insert Interval Array | Medium | 54 | 0.5% |
| 80 | Minimum Remove to Make Valid Parentheses String, Stack | Medium | 54 | 0.7% |
| 81 | Triangle Array, Dynamic Programming | Medium | 54 | 0.6% |
| 82 | Find Minimum in Rotated Sorted Array Array, Binary Search | Medium | 54 | 0.5% |
| 83 | The Maze Array, Depth-First Search, Breadth-First Search, Matrix | Medium | 54 | 0.6% |
| 84 | Remove All Adjacent Duplicates in String II String, Stack | Medium | 54 | 0.6% |
| 85 | Meeting Rooms II Array, Two Pointers, Greedy, Sorting, Heap (Priority Queue), Prefix Sum | Medium | 54 | 0.5% |
| 86 | Remove Nth Node From End of List Linked List, Two Pointers | Medium | 54 | 0.5% |
| 87 | Set Matrix Zeroes Array, Hash Table, Matrix | Medium | 54 | 0.6% |
| 88 | Valid Palindrome Two Pointers, String | Easy | 54 | 0.5% |
| 89 | Remove K Digits String, Stack, Greedy, Monotonic Stack | Medium | 54 | 0.4% |
| 90 | Next Greater Element III Math, Two Pointers, String | Medium | 54 | 0.4% |
| 91 | Next Permutation Array, Two Pointers | Medium | 54 | 0.5% |
| 92 | Pow(x, n) Math, Recursion | Medium | 43 | 0.4% |
| 93 | Word Search Array, String, Backtracking, Depth-First Search, Matrix | Medium | 43 | 0.5% |
| 94 | Populating Next Right Pointers in Each Node Linked List, Tree, Depth-First Search, Breadth-First Search, Binary Tree | Medium | 43 | 0.7% |
| 95 | Best Time to Buy and Sell Stock II Array, Dynamic Programming, Greedy | Medium | 43 | 0.7% |
| 96 | Copy List with Random Pointer Hash Table, Linked List | Medium | 43 | 0.6% |
| 97 | Product of Array Except Self Array, Prefix Sum | Medium | 43 | 0.7% |
| 98 | Flatten Nested List Iterator Stack, Tree, Depth-First Search, Design, Queue, Iterator | Medium | 43 | 0.7% |
| 99 | Longest Common Subsequence String, Dynamic Programming | Medium | 43 | 0.6% |
| 100 | Sort Characters By Frequency Hash Table, String, Sorting, Heap (Priority Queue), Bucket Sort, Counting | Medium | 43 | 0.8% |
| 101 | Basic Calculator II Math, String, Stack | Medium | 43 | 0.5% |
| 102 | Contiguous Array Array, Hash Table, Prefix Sum | Medium | 43 | 0.5% |
| 103 | Find Peak Element Array, Binary Search | Medium | 43 | 0.5% |
| 104 | Find K Pairs with Smallest Sums Array, Heap (Priority Queue) | Medium | 43 | 0.4% |
| 105 | Non-decreasing Array Array | Medium | 43 | 0.3% |
| 106 | Search in Rotated Sorted Array II Array, Binary Search | Medium | 43 | 0.4% |
| 107 | Reverse Integer Math | Medium | 43 | 0.3% |
| 108 | Combination Sum II Array, Backtracking | Medium | 43 | 0.6% |
| 109 | Count Different Palindromic Subsequences String, Dynamic Programming | Hard | 43 | 0.5% |
| 110 | Reverse Linked List II Linked List | Medium | 43 | 0.5% |
| 111 | Maximum Product Subarray Array, Dynamic Programming | Medium | 43 | 0.4% |
| 112 | Remove Letter To Equalize Frequency Hash Table, String, Counting | Easy | 43 | 0.2% |
| 113 | Find the Winner of the Circular Game Array, Math, Recursion, Queue, Simulation | Medium | 43 | 0.8% |
| 114 | Asteroid Collision Array, Stack, Simulation | Medium | 43 | 0.5% |
| 115 | Subsets Array, Backtracking, Bit Manipulation | Medium | 43 | 0.8% |
| 116 | Diameter of Binary Tree Tree, Depth-First Search, Binary Tree | Easy | 43 | 0.7% |
| 117 | Number of Islands II Array, Hash Table, Union-Find | Hard | 43 | 0.4% |
| 118 | Roman to Integer Hash Table, Math, String | Easy | 43 | 0.7% |
| 119 | Rising Temperature Database | Easy | 43 | 0.5% |
| 120 | Capacity To Ship Packages Within D Days Array, Binary Search | Medium | 43 | 0.7% |
| 121 | Edit Distance String, Dynamic Programming | Medium | 43 | 0.6% |
| 122 | Find All Duplicates in an Array Array, Hash Table, Sorting | Medium | 43 | 0.8% |
| 123 | N-Queens II Backtracking | Hard | 43 | 0.8% |
| 124 | Relative Sort Array Array, Hash Table, Sorting, Counting Sort | Easy | 43 | 0.8% |
| 125 | Number of Distinct Islands Array, Hash Table, Depth-First Search, Breadth-First Search, Union-Find, Sorting, Matrix, Hash Function | Medium | 43 | 0.6% |
| 126 | Find All Anagrams in a String Hash Table, String, Sliding Window | Medium | 43 | 0.5% |
| 127 | Longest Substring with At Least K Repeating Characters Hash Table, String, Divide and Conquer, Sliding Window | Medium | 43 | 0.5% |
| 128 | Linked List Cycle Hash Table, Linked List, Two Pointers | Easy | 43 | 0.5% |
| 129 | Meeting Rooms III Array, Hash Table, Sorting, Heap (Priority Queue), Simulation | Hard | 43 | 0.5% |
| 130 | Reconstruct Itinerary Array, String, Depth-First Search, Graph Theory, Sorting, Heap (Priority Queue), Eulerian Circuit | Hard | 43 | 0.4% |
| 131 | Candy Array, Greedy | Hard | 43 | 0.5% |
| 132 | Decode String String, Stack, Recursion | Medium | 43 | 0.6% |
| 133 | Nearest Exit from Entrance in Maze Array, Breadth-First Search, Matrix | Medium | 43 | 0.5% |
| 134 | Furthest Building You Can Reach Array, Greedy, Heap (Priority Queue) | Medium | 43 | 0.5% |
| 135 | Remove Duplicates from Sorted Array Array, Two Pointers | Easy | 43 | 0.6% |
| 136 | Bus Routes Array, Hash Table, Breadth-First Search | Hard | 43 | 0.5% |
| 137 | Find the Duplicate Number Array, Two Pointers, Binary Search, Bit Manipulation | Medium | 43 | 0.6% |
| 138 | Perfect Squares Math, Dynamic Programming, Breadth-First Search | Medium | 43 | 0.6% |
| 139 | Subarray Product Less Than K Array, Binary Search, Sliding Window, Prefix Sum | Medium | 43 | 0.5% |
| 140 | Basic Calculator Math, String, Stack, Recursion | Hard | 43 | 0.5% |
| 141 | Degree of an Array Array, Hash Table | Easy | 43 | 0.6% |
| 142 | Vertical Order Traversal of a Binary Tree Hash Table, Tree, Depth-First Search, Breadth-First Search, Sorting, Binary Tree | Hard | 43 | 0.5% |
| 143 | Sliding Window Maximum Array, Queue, Sliding Window, Heap (Priority Queue), Monotonic Queue | Hard | 43 | 0.5% |
| 144 | Cheapest Flights Within K Stops Dynamic Programming, Depth-First Search, Breadth-First Search, Graph Theory, Heap (Priority Queue), Shortest Path | Medium | 43 | 0.4% |
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.