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%