| | Longest Substring Without Repeating Characters Medium
#String
#Hash Map
#Sliding Window | Sliding Window | Medium | AmazonGoogle +2 | High | Solution → | |
| | Minimum Window Substring Hard
#String
#Hash Map
#Sliding Window | Sliding Window | Hard | FacebookAmazon +2 | High | Solution → | |
| | Sliding Window Maximum Hard
#Array
#Deque
#Sliding Window | Sliding Window | Hard | AmazonGoogle +1 | Medium | Solution → | |
| | Longest Repeating Character Replacement Medium
#String
#Sliding Window | Sliding Window | Medium | GoogleAmazon | Medium | Solution → | |
| | Permutation in String Medium
#String
#Hash Map
#Sliding Window | Sliding Window | Medium | MicrosoftAmazon | Medium | Solution → | |
| | Find All Anagrams in a String Medium
#String
#Hash Map
#Sliding Window | Sliding Window | Medium | FacebookUber | Medium | Solution → | |
| | Max Consecutive Ones III Medium
#Array
#Sliding Window
#Binary | Sliding Window | Medium | GoogleAmazon | Medium | Solution → | |
| | Subarray Product Less Than K Medium
#Array
#Sliding Window | Sliding Window | Medium | Amazon | Low | Solution → | |
| | Minimum Size Subarray Sum Medium
#Array
#Sliding Window
#Binary Search | Sliding Window | Medium | AmazonFacebook | Medium | Solution → | |
| | Fruit Into Baskets Medium
#Array
#Sliding Window
#Hash Map | Sliding Window | Medium | Google | Low | Solution → | |
| | Two Sum II - Input Array Is Sorted Medium
#Array
#Two Pointers
#Binary Search | Two Pointers | Medium | AmazonApple | High | Solution → | |
| | 3Sum Medium
#Array
#Two Pointers
#Sorting | Two Pointers | Medium | FacebookAmazon +2 | High | Solution → | |
| | Container With Most Water Medium
#Array
#Two Pointers
#Greedy | Two Pointers | Medium | AmazonFacebook +3 | High | Solution → | |
| | Trapping Rain Water Hard
#Array
#Two Pointers
#Stack | Two Pointers | Hard | AmazonGoogle +2 | High | Solution → | |
| | Valid Palindrome Easy
#String
#Two Pointers | Two Pointers | Easy | FacebookMicrosoft +1 | High | Solution → | |
| | Move Zeroes Easy
#Array
#Two Pointers | Two Pointers | Easy | FacebookBloomberg | Medium | Solution → | |
| | Remove Duplicates from Sorted Array Easy
#Array
#Two Pointers | Two Pointers | Easy | AppleMicrosoft | High | Solution → | |
| | Binary Search Easy
#Array
#Binary Search | Binary Search | Easy | AmazonGoogle +1 | High | Solution → | |
| | Search in Rotated Sorted Array Medium
#Array
#Binary Search | Binary Search | Medium | AmazonFacebook +2 | High | Solution → | |
| | Find Minimum in Rotated Sorted Array Medium
#Array
#Binary Search | Binary Search | Medium | AmazonMicrosoft | High | Solution → | |
| | Koko Eating Bananas Medium
#Array
#Binary Search | Binary Search | Medium | FacebookAmazon | Medium | Solution → | |
| | Find Peak Element Medium
#Array
#Binary Search | Binary Search | Medium | GoogleFacebook | Medium | Solution → | |
| | Time Based Key-Value Store Medium
#Hash Map
#Binary Search
#Design | Binary Search | Medium | GoogleAirbnb +1 | Medium | Solution → | |
| | Subarray Sum Equals K Medium
#Array
#Hash Map
#Prefix Sum | Prefix Sum | Medium | FacebookGoogle +3 | High | Solution → | |
| | Product of Array Except Self Medium
#Array
#Prefix Product | Prefix Sum | Medium | AmazonFacebook +2 | High | Solution → | |
| | Range Sum Query - Immutable Easy
#Array
#Design
#Prefix Sum | Prefix Sum | Easy | Amazon | Medium | Solution → | |
| | Contiguous Array Medium
#Array
#Hash Map
#Prefix Sum | Prefix Sum | Medium | Facebook | Medium | Solution → | |
| | Two Sum Easy
#Array
#Hash Map | Hash Map / Set | Easy | AmazonGoogle +3 | High | Solution → | |
| | Group Anagrams Medium
#String
#Hash Map
#Sorting | Hash Map / Set | Medium | AmazonFacebook +2 | High | Solution → | |
| | Top K Frequent Elements Medium
#Array
#Hash Map
#Heap | Hash Map / Set | Medium | FacebookAmazon +1 | High | Solution → | |
| | Valid Anagram Easy
#String
#Hash Map
#Sorting | Hash Map / Set | Easy | AmazonApple +1 | High | Solution → | |
| | Longest Consecutive Sequence Medium
#Array
#Hash Set | Hash Map / Set | Medium | GoogleFacebook +1 | High | Solution → | |
| | Valid Parentheses Easy
#String
#Stack | Stack | Easy | GoogleAmazon +2 | High | Solution → | |
| | Min Stack Medium
#Stack
#Design | Stack | Medium | AmazonBloomberg +1 | High | Solution → | |
| | Evaluate Reverse Polish Notation Medium
#Array
#Math
#Stack | Stack | Medium | AmazonLinkedIn | Medium | Solution → | |
| | Daily Temperatures Medium
#Array
#Stack
#Monotonic Stack | Stack | Medium | AmazonGoogle +1 | High | Solution → | |
| | Decode String Medium
#String
#Stack
#Recursion | Stack | Medium | GoogleAmazon +1 | Medium | Solution → | |
| | Number of Islands Medium
#Array
#DFS
#BFS | Queue / BFS | Medium | AmazonGoogle +2 | High | Solution → | |
| | Rotting Oranges Medium
#Array
#BFS
#Matrix | Queue / BFS | Medium | AmazonGoogle | High | Solution → | |
| | Binary Tree Level Order Traversal Medium
#Tree
#BFS | Queue / BFS | Medium | AmazonFacebook +1 | High | Solution → | |
| | Word Ladder Hard
#Hash Set
#BFS
#String | Queue / BFS | Hard | AmazonFacebook +2 | Medium | Solution → | |
| | Kth Largest Element in an Array Medium
#Array
#Heap
#Sorting | Heap / Priority Queue | Medium | FacebookAmazon +2 | High | Solution → | |
| | Find Median from Data Stream Hard
#Two Heaps
#Design
#Sorting | Heap / Priority Queue | Hard | AmazonMicrosoft +1 | High | Solution → | |
| | Task Scheduler Medium
#Array
#Heap
#Greedy | Heap / Priority Queue | Medium | FacebookAmazon | Medium | Solution → | |
| | Merge K Sorted Lists Hard
#Linked List
#Heap
#Divide and Conquer | Heap / Priority Queue | Hard | AmazonFacebook +2 | High | Solution → | |
| | Reverse Linked List Easy
#Linked List
#Recursion | Linked List | Easy | AmazonFacebook +2 | High | Solution → | |
| | Linked List Cycle Easy
#Linked List
#Two Pointers
#Hash Table | Linked List | Easy | AmazonMicrosoft +1 | High | Solution → | |
| | Merge Two Sorted Lists Easy
#Linked List
#Recursion | Linked List | Easy | AmazonMicrosoft +1 | High | Solution → | |
| | Reorder List Medium
#Linked List
#Two Pointers
#Stack | Linked List | Medium | AmazonFacebook | Medium | Solution → | |
| | Invert Binary Tree Easy
#Tree
#DFS
#BFS | Trees / DFS | Easy | AmazonApple +1 | High | Solution → | |
| | Maximum Depth of Binary Tree Easy
#Tree
#DFS
#BFS | Trees / DFS | Easy | AmazonLinkedIn | High | Solution → | |
| | Validate Binary Search Tree Medium
#Tree
#DFS
#BST | Trees / DFS | Medium | AmazonBloomberg +2 | High | Solution → | |
| | Lowest Common Ancestor of a BST Medium
#Tree
#DFS
#BST | Trees / DFS | Medium | AmazonFacebook +1 | High | Solution → | |
| | Binary Tree Maximum Path Sum Hard
#Tree
#DFS
#DP | Trees / DFS | Hard | AmazonFacebook +2 | High | Solution → | |
| | Serialize and Deserialize Binary Tree Hard
#Tree
#DFS
#BFS | Trees / DFS | Hard | GoogleAmazon +2 | Medium | Solution → | |
| | Clone Graph Medium
#Graph
#DFS
#BFS | Graphs | Medium | FacebookAmazon +1 | High | Solution → | |
| | Pacific Atlantic Water Flow Medium
#Graph
#DFS
#BFS | Graphs | Medium | GoogleFacebook +1 | Medium | Solution → | |
| | Number of Connected Components in Undirected Graph ★ Medium
#Graph
#DFS
#Union Find | Graphs | Medium | LinkedInGoogle +1 | Medium | Solution → | |
| | Climbing Stairs Easy
#DP
#Math
#Memoization | Dynamic Programming | Easy | AmazonAdobe +1 | High | Solution → | |
| | House Robber Medium
#Array
#DP | Dynamic Programming | Medium | AmazonGoogle +1 | High | Solution → | |
| | Coin Change Medium
#Array
#DP
#BFS | Dynamic Programming | Medium | AmazonGoogle +2 | High | Solution → | |
| | Longest Increasing Subsequence Medium
#Array
#DP
#Binary Search | Dynamic Programming | Medium | GoogleAmazon +1 | High | Solution → | |
| | Longest Common Subsequence Medium
#String
#DP | Dynamic Programming | Medium | GoogleAmazon +1 | High | Solution → | |
| | Word Break Medium
#String
#DP
#Hash Set | Dynamic Programming | Medium | AmazonGoogle +2 | High | Solution → | |
| | Edit Distance Hard
#String
#DP | Dynamic Programming | Hard | GoogleAmazon +2 | Medium | Solution → | |
| | Unique Paths Medium
#Math
#DP
#Combinatorics | Dynamic Programming | Medium | AmazonGoogle +1 | High | Solution → | |
| | Maximum Subarray Medium
#Array
#DP
#Divide and Conquer | Dynamic Programming | Medium | AmazonLinkedIn +2 | High | Solution → | |
| | Decode Ways Medium
#String
#DP | Dynamic Programming | Medium | AmazonFacebook +1 | High | Solution → | |
| | Jump Game Medium
#Array
#Greedy
#DP | Greedy | Medium | AmazonMicrosoft +1 | High | Solution → | |
| | Jump Game II Medium
#Array
#Greedy
#DP | Greedy | Medium | AmazonGoogle +1 | High | Solution → | |
| | Gas Station Medium
#Array
#Greedy | Greedy | Medium | AmazonUber +1 | Medium | Solution → | |
| | Permutations Medium
#Array
#Backtracking | Backtracking | Medium | LinkedInMicrosoft +1 | High | Solution → | |
| | Subsets Medium
#Array
#Backtracking
#Bit Manipulation | Backtracking | Medium | FacebookAmazon +1 | High | Solution → | |
| | Combination Sum Medium
#Array
#Backtracking | Backtracking | Medium | AmazonFacebook +1 | High | Solution → | |
| | Word Search Medium
#Array
#Matrix
#Backtracking | Backtracking | Medium | AmazonFacebook +2 | High | Solution → | |
| | Implement Trie (Prefix Tree) Medium
#Design
#Trie | Trie | Medium | AmazonGoogle +2 | High | Solution → | |
| | Design Add and Search Words Data Structure Medium
#Design
#Trie
#DFS | Trie | Medium | FacebookBloomberg | Medium | Solution → | |
| | Redundant Connection Medium
#Graph
#Union Find
#DFS | Union Find | Medium | GoogleAmazon | Medium | Solution → | |
| | Accounts Merge Medium
#Graph
#Union Find
#DFS | Union Find | Medium | FacebookAmazon +1 | Medium | Solution → | |
| | Largest Rectangle in Histogram Hard
#Array
#Stack
#Monotonic Stack | Monotonic Stack | Hard | AmazonGoogle +1 | High | Solution → | |
| | Next Greater Element I Easy
#Array
#Hash Map
#Stack | Monotonic Stack | Easy | Apple | Medium | Solution → | |
| | Course Schedule Medium
#Graph
#DFS
#BFS | Topological Sort | Medium | AmazonFacebook +2 | High | Solution → | |
| | Course Schedule II Medium
#Graph
#DFS
#BFS | Topological Sort | Medium | FacebookAmazon +1 | High | Solution → | |
| | Single Number Easy
#Array
#Bit Manipulation | Bit Manipulation | Easy | AmazonApple +1 | High | Solution → | |
| | Missing Number Easy
#Array
#Math
#Bit Manipulation | Bit Manipulation | Easy | MicrosoftAmazon | High | Solution → | |
| | Counting Bits Easy
#DP
#Bit Manipulation | Bit Manipulation | Easy | GoogleFacebook | High | Solution → | |
| | Merge Intervals Medium
#Array
#Sorting | Intervals | Medium | FacebookAmazon +3 | High | Solution → | |
| | Insert Interval Medium
#Array | Intervals | Medium | LinkedInGoogle +2 | High | Solution → | |
| | Rotate Image Medium
#Array
#Matrix
#Math | Matrix | Medium | AmazonMicrosoft +1 | High | Solution → | |
| | Spiral Matrix Medium
#Array
#Matrix
#Simulation | Matrix | Medium | AmazonMicrosoft +2 | High | Solution → | |
| | Set Matrix Zeroes Medium
#Array
#Matrix | Matrix | Medium | AmazonMicrosoft +1 | High | Solution → | |
| | 4Sum Medium
#Array
#Sorting
#Two Pointers | Two Pointers | Medium | AmazonAdobe | Medium | Solution → | |
| | Sort Colors Medium
#Array
#Sorting
#Two Pointers | Two Pointers | Medium | FacebookMicrosoft +1 | High | Solution → | |
| | Squares of a Sorted Array Easy
#Array
#Two Pointers
#Sorting | Two Pointers | Easy | GoogleAmazon +1 | High | Solution → | |
| | Boats to Save People Medium
#Array
#Two Pointers
#Greedy | Two Pointers | Medium | AmazonGoogle | Medium | Solution → | |
| | Search a 2D Matrix Medium
#Array
#Binary Search
#Matrix | Binary Search | Medium | AmazonMicrosoft +1 | High | Solution → | |
| | Capacity to Ship Packages Within D Days Medium
#Array
#Binary Search | Binary Search | Medium | AmazonFacebook +1 | High | Solution → | |
| | Split Array Largest Sum Hard
#Array
#Binary Search
#Dynamic Programming | Binary Search | Hard | GoogleFacebook +1 | Medium | Solution → | |
| | Median of Two Sorted Arrays Hard
#Array
#Binary Search
#Divide and Conquer | Binary Search | Hard | GoogleAmazon +3 | High | Solution → | |
| | Contains Duplicate Easy
#Array
#Hash Table
#Sorting | Hash Map / Set | Easy | AmazonGoogle +1 | High | Solution → | |
| | Word Pattern Easy
#Hash Table
#String | Hash Map / Set | Easy | LinkedInDropbox | Medium | Solution → | |
| | Isomorphic Strings Easy
#Hash Table
#String | Hash Map / Set | Easy | LinkedInAmazon | Medium | Solution → | |
| | LRU Cache Medium
#Hash Table
#Linked List
#Design | Hash Map / Set | Medium | AmazonMicrosoft +5 | High | Solution → | |
| | Asteroid Collision Medium
#Array
#Stack
#Simulation | Stack | Medium | AmazonGoogle +1 | Medium | Solution → | |
| | Remove K Digits Medium
#String
#Stack
#Greedy | Stack | Medium | GoogleFacebook | Medium | Solution → | |
| | Car Fleet Medium
#Array
#Stack
#Sorting | Stack | Medium | AmazonGoogle | Medium | Solution → | |
| | 01 Matrix Medium
#Array
#BFS
#Matrix | Queue / BFS | Medium | FacebookAmazon +1 | High | Solution → | |
| | Walls and Gates ★ Medium
#Array
#BFS
#Matrix | Queue / BFS | Medium | FacebookAmazon | Medium | Solution → | |
| | Shortest Path in Binary Matrix Medium
#Array
#BFS
#Matrix | Queue / BFS | Medium | AmazonGoogle +1 | Medium | Solution → | |
| | Open the Lock Medium
#Array
#Hash Table
#BFS | Queue / BFS | Medium | GoogleAmazon | Medium | Solution → | |
| | K Closest Points to Origin Medium
#Array
#Math
#Divide and Conquer | Heap / Priority Queue | Medium | FacebookAmazon +2 | High | Solution → | |
| | Reorganize String Medium
#Hash Table
#String
#Greedy | Heap / Priority Queue | Medium | AmazonGoogle +1 | Medium | Solution → | |
| | Top K Frequent Words Medium
#Hash Table
#String
#Trie | Heap / Priority Queue | Medium | AmazonBloomberg +1 | Medium | Solution → | |
| | Add Two Numbers Medium
#Linked List
#Math
#Recursion | Linked List | Medium | AmazonMicrosoft +3 | High | Solution → | |
| | Remove Nth Node From End of List Medium
#Linked List
#Two Pointers | Linked List | Medium | AmazonMicrosoft +2 | High | Solution → | |
| | Copy List with Random Pointer Medium
#Hash Table
#Linked List | Linked List | Medium | AmazonMicrosoft +2 | High | Solution → | |
| | Palindrome Linked List Easy
#Linked List
#Two Pointers
#Stack | Linked List | Easy | AmazonFacebook +2 | High | Solution → | |
| | Diameter of Binary Tree Easy
#Tree
#DFS
#Binary Tree | Trees / DFS | Easy | FacebookAmazon +1 | High | Solution → | |
| | Symmetric Tree Easy
#Tree
#DFS
#BFS | Trees / DFS | Easy | AmazonMicrosoft +1 | High | Solution → | |
| | Binary Tree Right Side View Medium
#Tree
#DFS
#BFS | Trees / DFS | Medium | FacebookAmazon +1 | High | Solution → | |
| | Kth Smallest Element in a BST Medium
#Tree
#DFS
#BST | Trees / DFS | Medium | AmazonFacebook +1 | High | Solution → | |
| | Construct Binary Tree from Preorder and Inorder Traversal Medium
#Array
#Hash Table
#Divide and Conquer | Trees / DFS | Medium | AmazonMicrosoft +1 | Medium | Solution → | |
| | Path Sum II Medium
#Backtracking
#Tree
#DFS | Trees / DFS | Medium | AmazonMicrosoft +1 | Medium | Solution → | |
| | Surrounded Regions Medium
#Array
#DFS
#BFS | Graphs | Medium | GoogleFacebook +1 | Medium | Solution → | |
| | Minimum Height Trees Medium
#DFS
#BFS
#Graph | Graphs | Medium | GoogleAmazon | Medium | Solution → | |
| | Network Delay Time Medium
#DFS
#BFS
#Graph | Graphs | Medium | AmazonGoogle +1 | Medium | Solution → | |
| | Min Cost Climbing Stairs Easy
#Array
#Dynamic Programming | Dynamic Programming | Easy | AmazonGoogle +1 | High | Solution → | |
| | House Robber II Medium
#Array
#Dynamic Programming | Dynamic Programming | Medium | AmazonGoogle +1 | High | Solution → | |
| | Partition Equal Subset Sum Medium
#Array
#Dynamic Programming | Dynamic Programming | Medium | AmazonFacebook +1 | High | Solution → | |
| | Target Sum Medium
#Array
#Dynamic Programming
#Backtracking | Dynamic Programming | Medium | FacebookAmazon +1 | High | Solution → | |
| | Best Time to Buy and Sell Stock Easy
#Array
#Dynamic Programming | Dynamic Programming | Easy | AmazonFacebook +3 | High | Solution → | |
| | Palindromic Substrings Medium
#String
#Dynamic Programming | Dynamic Programming | Medium | FacebookAmazon +1 | High | Solution → | |
| | Longest Palindromic Substring Medium
#String
#Dynamic Programming | Dynamic Programming | Medium | AmazonMicrosoft +2 | High | Solution → | |
| | Best Time to Buy and Sell Stock with Cooldown Medium
#Array
#Dynamic Programming | Dynamic Programming | Medium | AmazonGoogle | Medium | Solution → | |
| | Non-overlapping Intervals Medium
#Array
#Greedy
#Dynamic Programming | Greedy | Medium | GoogleFacebook | High | Solution → | |
| | Meeting Rooms II ★ Medium
#Array
#Greedy
#Sorting | Greedy | Medium | FacebookAmazon +4 | High | Solution → | |
| | Queue Reconstruction by Height Medium
#Array
#Greedy
#Sorting | Greedy | Medium | GoogleFacebook | Medium | Solution → | |
| | Letter Combinations of a Phone Number Medium
#Hash Table
#String
#Backtracking | Backtracking | Medium | AmazonFacebook +3 | High | Solution → | |
| | Generate Parentheses Medium
#String
#Dynamic Programming
#Backtracking | Backtracking | Medium | AmazonGoogle +2 | High | Solution → | |
| | N-Queens Hard
#Array
#Backtracking | Backtracking | Hard | AmazonMicrosoft | Medium | Solution → | |
| | Palindrome Partitioning Medium
#String
#Dynamic Programming
#Backtracking | Backtracking | Medium | AmazonFacebook +1 | Medium | Solution → | |
| | Word Search II Hard
#Array
#String
#Backtracking | Trie | Hard | AmazonMicrosoft +1 | Medium | Solution → | |
| | Longest Word in Dictionary Medium
#Array
#Hash Table
#String | Trie | Medium | Google | Low | Solution → | |
| | Number of Provinces Medium
#DFS
#BFS
#Union-Find | Union Find | Medium | AmazonFacebook +1 | High | Solution → | |
| | Satisfiability of Equality Equations Medium
#Array
#String
#Union-Find | Union Find | Medium | GoogleAmazon | Medium | Solution → | |
| | Sum of Subarray Minimums Medium
#Array
#Dynamic Programming
#Stack | Monotonic Stack | Medium | GoogleAmazon | Medium | Solution → | |
| | Online Stock Span Medium
#Stack
#Design
#Monotonic Stack | Monotonic Stack | Medium | AmazonMicrosoft | Medium | Solution → | |
| | Number of 1 Bits Easy
#Divide and Conquer
#Bit Manipulation | Bit Manipulation | Easy | AppleMicrosoft +1 | High | Solution → | |
| | Reverse Bits Easy
#Divide and Conquer
#Bit Manipulation | Bit Manipulation | Easy | AppleAmazon | Medium | Solution → | |
| | Sum of Two Integers Medium
#Math
#Bit Manipulation | Bit Manipulation | Medium | FacebookAmazon +1 | Medium | Solution → | |
| | Minimum Interval to Include Each Query Hard
#Array
#Binary Search
#Line Sweep | Intervals | Hard | GoogleAmazon | Low | Solution → | |
| | Meeting Rooms ★ Easy
#Array
#Sorting | Intervals | Easy | FacebookAmazon +2 | High | Solution → | |
| | Maximal Square Medium
#Array
#Dynamic Programming
#Matrix | Matrix | Medium | FacebookAmazon +2 | High | Solution → | |
| | Game of Life Medium
#Array
#Matrix
#Simulation | Matrix | Medium | GoogleAmazon +2 | Medium | Solution → | |
| | Find Pivot Index Easy
#Array
#Prefix Sum | Prefix Sum | Easy | AmazonGoogle | High | Solution → | |
| | Running Sum of 1D Array Easy
#Array
#Prefix Sum | Prefix Sum | Easy | AmazonApple | Medium | Solution → | |
| | Minimum Operations to Reduce X to Zero Medium
#Array
#Hash Table
#Binary Search | Sliding Window | Medium | AmazonGoogle | Medium | Solution → | |
| | Longest Subarray of 1's After Deleting One Element Medium
#Array
#Dynamic Programming
#Sliding Window | Sliding Window | Medium | AmazonGoogle +1 | Medium | Solution → | |
| | Count Number of Nice Subarrays Medium
#Array
#Hash Table
#Math | Sliding Window | Medium | Amazon | Medium | Solution → | |
| | Valid Palindrome II Easy
#String
#Greedy
#Two Pointers | Two Pointers | Easy | FacebookAmazon +1 | High | Solution → | |
| | Minimum Length of String After Deleting Similar Ends Medium
#String
#Two Pointers | Two Pointers | Medium | Google | Low | Solution → | |
| | 4Sum II Medium
#Array
#Hash Table | Hash Map / Set | Medium | AmazonGoogle | Medium | Solution → | |
| | Number of Good Pairs Easy
#Array
#Hash Table
#Math | Hash Map / Set | Easy | Amazon | Medium | Solution → | |
| | Subarray Sum Divisible by K Medium
#Array
#Hash Table
#Prefix Sum | Hash Map / Set | Medium | FacebookAmazon +1 | Medium | Solution → | |
| | Basic Calculator II Medium
#Math
#String
#Stack | Stack | Medium | AmazonFacebook +3 | High | Solution → | |
| | Simplify Path Medium
#String
#Stack | Stack | Medium | FacebookAirbnb +1 | Medium | Solution → | |
| | Minimum Genetic Mutation Medium
#Hash Table
#String
#BFS | Queue / BFS | Medium | GoogleAmazon | Medium | Solution → | |
| | Jump Game III Medium
#Array
#DFS
#BFS | Queue / BFS | Medium | AmazonGoogle | Medium | Solution → | |
| | Find K Pairs with Smallest Sums Medium
#Array
#Heap | Heap / Priority Queue | Medium | AmazonGoogle +1 | Medium | Solution → | |
| | Minimum Cost to Connect Sticks ★ Medium
#Array
#Greedy
#Heap | Heap / Priority Queue | Medium | AmazonFacebook | Medium | Solution → | |
| | Swap Nodes in Pairs Medium
#Linked List
#Recursion | Linked List | Medium | AmazonMicrosoft +1 | Medium | Solution → | |
| | Rotate List Medium
#Linked List
#Two Pointers | Linked List | Medium | AmazonMicrosoft | Medium | Solution → | |
| | Reverse Nodes in k-Group Hard
#Linked List
#Recursion | Linked List | Hard | AmazonMicrosoft +2 | High | Solution → | |
| | Count Good Nodes in Binary Tree Medium
#Tree
#DFS
#BFS | Trees / DFS | Medium | FacebookAmazon | Medium | Solution → | |
| | Flatten Binary Tree to Linked List Medium
#Linked List
#Stack
#Tree | Trees / DFS | Medium | AmazonMicrosoft +1 | Medium | Solution → | |
| | Sum Root to Leaf Numbers Medium
#Tree
#DFS
#BFS | Trees / DFS | Medium | AmazonGoogle +1 | Medium | Solution → | |
| | Populating Next Right Pointers in Each Node Medium
#Linked List
#Tree
#DFS | Trees / DFS | Medium | FacebookAmazon +1 | Medium | Solution → | |
| | Find Eventual Safe States Medium
#DFS
#BFS
#Graph | Graphs | Medium | GoogleAmazon | Medium | Solution → | |
| | All Paths From Source to Target Medium
#Backtracking
#DFS
#BFS | Graphs | Medium | AmazonFacebook +1 | Medium | Solution → | |
| | Cheapest Flights Within K Stops Medium
#Dynamic Programming
#DFS
#BFS | Graphs | Medium | AmazonGoogle +1 | High | Solution → | |
| | Maximum Product Subarray Medium
#Array
#Dynamic Programming | Dynamic Programming | Medium | AmazonGoogle +4 | High | Solution → | |
| | Triangle Medium
#Array
#Dynamic Programming | Dynamic Programming | Medium | AmazonApple | Medium | Solution → | |
| | Minimum Path Sum Medium
#Array
#Dynamic Programming
#Matrix | Dynamic Programming | Medium | AmazonGoogle +1 | High | Solution → | |
| | Perfect Squares Medium
#Math
#Dynamic Programming
#BFS | Dynamic Programming | Medium | GoogleAmazon | Medium | Solution → | |
| | Regular Expression Matching Hard
#String
#Dynamic Programming
#Recursion | Dynamic Programming | Hard | GoogleFacebook +2 | Medium | Solution → | |
| | Interleaving String Medium
#String
#Dynamic Programming
#BFS | Dynamic Programming | Medium | AmazonGoogle +1 | Medium | Solution → | |
| | Best Time to Buy and Sell Stock with Transaction Fee Medium
#Array
#Dynamic Programming
#Greedy | Dynamic Programming | Medium | AmazonGoogle | Medium | Solution → | |
| | Integer Break Medium
#Math
#Dynamic Programming | Dynamic Programming | Medium | Google | Low | Solution → | |
| | Minimum Number of Arrows to Burst Balloons Medium
#Array
#Greedy
#Sorting | Greedy | Medium | MicrosoftAmazon | Medium | Solution → | |
| | Candy Hard
#Array
#Greedy | Greedy | Hard | AmazonGoogle | Medium | Solution → | |
| | Combination Sum II Medium
#Array
#Backtracking | Backtracking | Medium | AmazonAdobe | Medium | Solution → | |
| | Subsets II Medium
#Array
#Backtracking
#Bit Manipulation | Backtracking | Medium | FacebookAmazon | Medium | Solution → | |
| | Replace Words Medium
#Array
#Hash Table
#String | Trie | Medium | FacebookAmazon | Medium | Solution → | |
| | Swim in Rising Water Hard
#Array
#Binary Search
#DFS | Union Find | Hard | GoogleAmazon | Medium | Solution → | |
| | Most Stones Removed with Same Row or Column Medium
#Hash Table
#DFS
#Union-Find | Union Find | Medium | FacebookAmazon | Medium | Solution → | |
| | 132 Pattern Medium
#Array
#Binary Search
#Stack | Monotonic Stack | Medium | GoogleAmazon +1 | Medium | Solution → | |
| | Remove Duplicate Letters Medium
#String
#Stack
#Greedy | Monotonic Stack | Medium | GoogleLyft | Medium | Solution → | |
| | Parallel Courses ★ Medium
#Graph
#Topological Sort
#BFS | Topological Sort | Medium | AmazonGoogle | Medium | Solution → | |
| | Sequence Reconstruction ★ Medium
#Array
#Graph
#Topological Sort | Topological Sort | Medium | GoogleSnapchat | Low | Solution → | |
| | Single Number II Medium
#Array
#Bit Manipulation | Bit Manipulation | Medium | AmazonFacebook | Medium | Solution → | |
| | Power of Two Easy
#Math
#Bit Manipulation
#Recursion | Bit Manipulation | Easy | GoogleApple | Medium | Solution → | |
| | Search a 2D Matrix II Medium
#Array
#Binary Search
#Divide and Conquer | Matrix | Medium | AmazonApple +2 | High | Solution → | |
| | Count Negative Numbers in a Sorted Matrix Easy
#Array
#Binary Search
#Matrix | Matrix | Easy | AmazonGoogle | Medium | Solution → | |
| | Frequency of the Most Frequent Element Medium
#Array
#Binary Search
#Greedy | Sliding Window | Medium | AmazonGoogle | Medium | Solution → | |
| | Maximum Number of Vowels in a Substring of Given Length Medium
#String
#Sliding Window | Sliding Window | Medium | GoogleBloomberg +1 | Medium | Solution → | |
| | Minimum Average Difference Medium
#Array
#Prefix Sum | Prefix Sum | Medium | Amazon | Low | Solution → | |
| | Alien Dictionary ★ Hard
#Array
#String
#Graph | Topological Sort | Hard | FacebookAmazon +3 | High | Solution → | |
| | Graph Valid Tree ★ Medium
#Depth-First Search
#Breadth-First Search
#Union Find | Graphs | Medium | GoogleFacebook +2 | High | Solution → | |
| | Encode and Decode Strings ★ Medium
#Array
#String
#Design | Two Pointers | Medium | GoogleFacebook +2 | Medium | Solution → | |
| | Same Tree Easy
#Tree
#Depth-First Search
#Breadth-First Search | Trees / DFS | Easy | AmazonGoogle +1 | High | Solution → | |
| | Subtree of Another Tree Easy
#Tree
#Depth-First Search
#String Matching | Trees / DFS | Easy | AmazonFacebook +1 | High | Solution → | |
| | Best Time to Buy and Sell the Stocks - 2 Medium
#Array | Two Pointers | Medium | AmazonGoogle +1 | High | Solution → | |
| | 3Sum Closest Medium
#Array | Two Pointers | Medium | AmazonGoogle +1 | High | Solution → | |
| | Intersection of two Arrays Medium
#Array | Two Pointers | Medium | AmazonGoogle +1 | High | Solution → | |
| | Next Permutation Medium
#Array | Backtracking | Medium | AmazonGoogle +1 | High | Solution → | |
| | Magic Index Medium
#Array | Binary Search | Medium | AmazonGoogle +1 | High | Solution → | |
| | Maximum Sum Rectangle Medium
#Array | Two Pointers | Medium | AmazonGoogle +1 | High | Solution → | |
| | Merge sorted arrays Medium
#Array | Binary Search | Medium | AmazonGoogle +1 | High | Solution → | |
| | Rotate Array Medium
#Array | Two Pointers | Medium | AmazonGoogle +1 | High | Solution → | |
| | Majority Element Easy
#Array | Two Pointers | Easy | AmazonGoogle +1 | High | Solution → | |
| | Majority Element II Easy
#Array | Two Pointers | Easy | AmazonGoogle +1 | High | Solution → | |
| | Next Greater Element III Medium
#Array | Two Pointers | Medium | AmazonGoogle +1 | High | Solution → | |
| | Max Chunks To Make Sorted Medium
#Array | Prefix Sum | Medium | AmazonGoogle +1 | High | Solution → | |
| | Max Chunks To Make Sorted II Medium
#Array | Prefix Sum | Medium | AmazonGoogle +1 | High | Solution → | |
| | Merge Sort Medium
#Array | Two Pointers | Medium | AmazonGoogle +1 | High | Solution → | |
| | Count Inversions Medium
#Array | Two Pointers | Medium | AmazonGoogle +1 | High | Solution → | |
| | First Missing Positive Medium
#Array | Two Pointers | Medium | AmazonGoogle +1 | High | Solution → | |
| | Repeat and Missing Number Array Medium
#Array | Two Pointers | Medium | AmazonGoogle +1 | High | Solution → | |
| | Minimum Platforms Medium
#Array | Two Pointers | Medium | AmazonGoogle +1 | High | Solution → | |
| | Max sum path in two arrays Medium
#Array | Two Pointers | Medium | AmazonGoogle +1 | High | Solution → | |
| | Pairs of Songs With Total Durations Divisible by 60 Medium
#Array | Two Pointers | Medium | AmazonGoogle +1 | High | Solution → | |
| | Rectangle Overlap Medium
#Array | Two Pointers | Medium | AmazonGoogle +1 | High | Solution → | |
| | Find the Duplicate Number Medium
#Array | Two Pointers | Medium | AmazonGoogle +1 | High | Solution → | |
| | Segregate Even and Odd numbers Medium
#Array | Two Pointers | Medium | AmazonGoogle +1 | High | Solution → | |
| | Subarray with 0 sum exist Medium
#Array | Two Pointers | Medium | AmazonGoogle +1 | High | Solution → | |
| | Count Numbers with Unique Digits Medium
#Array | Two Pointers | Medium | AmazonGoogle +1 | High | Solution → | |
| | Distribute Candies Medium
#Array | Two Pointers | Medium | AmazonGoogle +1 | High | Solution → | |
| | Transpose Matrix Medium
#Array | Two Pointers | Medium | AmazonGoogle +1 | High | Solution → | |
| | Common Elements from 3 Sorted Arrays Medium
#Array | Binary Search | Medium | AmazonGoogle +1 | High | Solution → | |
| | Pascals Triangle Medium
#Array | Two Pointers | Medium | AmazonGoogle +1 | High | Solution → | |
| | Insert Delete GetRandom in O Medium
#Array | Two Pointers | Medium | AmazonGoogle +1 | High | Solution → | |
| | Sign of the Product of an Array Medium
#Array | Two Pointers | Medium | AmazonGoogle +1 | High | Solution → | |
| | Find N Unique Integers Sum up to Zero Medium
#Array | Two Pointers | Medium | AmazonGoogle +1 | High | Solution → | |
| | Shuffle an Array Medium
#Array | Two Pointers | Medium | AmazonGoogle +1 | High | Solution → | |
| | Count Primes Medium
#Array | Two Pointers | Medium | AmazonGoogle +1 | High | Solution → | |
| | Power of Three Medium
#Array | Two Pointers | Medium | AmazonGoogle +1 | High | Solution → | |
| | Hamming Distance Medium
#Array | Two Pointers | Medium | AmazonGoogle +1 | High | Solution → | |
| | Excel Sheet Column Number Medium
#Array | Two Pointers | Medium | AmazonGoogle +1 | High | Solution → | |
| | Excel Sheet Column Title Medium
#Array | Two Pointers | Medium | AmazonGoogle +1 | High | Solution → | |
| | Happy Number Medium
#Array | Two Pointers | Medium | AmazonGoogle +1 | High | Solution → | |
| | Assign Cookies Medium
#Array | Two Pointers | Medium | AmazonGoogle +1 | High | Solution → | |
| | Consecutive 1's not allowed Medium
#String | Sliding Window | Medium | AmazonGoogle +1 | High | Solution → | |
| | Minimum changes to make alternating binary string Medium
#String | Sliding Window | Medium | AmazonGoogle +1 | High | Solution → | |
| | Find all permutations of a string Medium
#String | Backtracking | Medium | AmazonGoogle +1 | High | Solution → | |
| | Find all permutations of a given string without duplicates Medium
#String | Backtracking | Medium | AmazonGoogle +1 | High | Solution → | |
| | Reverse words in a given string Medium
#String | Two Pointers | Medium | AmazonGoogle +1 | High | Solution → | |
| | Reverse Words in a String Medium
#String | Two Pointers | Medium | AmazonGoogle +1 | High | Solution → | |
| | String to Integer Medium
#String | Sliding Window | Medium | AmazonGoogle +1 | High | Solution → | |
| | Length of Last Word Medium
#String | Sliding Window | Medium | AmazonGoogle +1 | High | Solution → | |
| | Run Length Encoding Medium
#String | Sliding Window | Medium | AmazonGoogle +1 | High | Solution → | |
| | Longest Common Prefix Medium
#String | Sliding Window | Medium | AmazonGoogle +1 | High | Solution → | |
| | Largest Alphabetic Character present in the String Medium
#String | Sliding Window | Medium | AmazonGoogle +1 | High | Solution → | |
| | Minimum Number of Moves to Make Palindrome Medium
#String | Two Pointers | Medium | AmazonGoogle +1 | High | Solution → | |
| | Roman to Integer Medium
#String | Sliding Window | Medium | AmazonGoogle +1 | High | Solution → | |
| | Integer to Roman Medium
#String | Sliding Window | Medium | AmazonGoogle +1 | High | Solution → | |
| | First Unique Character in a String Medium
#String | Sliding Window | Medium | AmazonGoogle +1 | High | Solution → | |
| | Valid Tic Toe State Medium
#String | Sliding Window | Medium | AmazonGoogle +1 | High | Solution → | |
| | Find the Index of the First Occurrence in a String Medium
#String | Sliding Window | Medium | AmazonGoogle +1 | High | Solution → | |
| | Longest Valid Parentheses Easy
#String | Backtracking | Easy | AmazonGoogle +1 | High | Solution → | |
| | Sort an Almost Sorted Array Medium
#Heap
#Priority Queue | Heap / Priority Queue | Medium | AmazonGoogle +1 | High | Solution → | |
| | Find K Closest Elements Medium
#Heap
#Priority Queue | Heap / Priority Queue | Medium | AmazonGoogle +1 | High | Solution → | |
| | Connect Ropes to Minimize the Cost Medium
#Heap
#Priority Queue | Heap / Priority Queue | Medium | AmazonGoogle +1 | High | Solution → | |
| | The sum of Elements between k1 smallest and k2 smallest numbers Medium
#Heap
#Priority Queue | Heap / Priority Queue | Medium | AmazonGoogle +1 | High | Solution → | |
| | Kth Largest Element in a Stream Medium
#Heap
#Priority Queue | Heap / Priority Queue | Medium | AmazonGoogle +1 | High | Solution → | |
| | Find the intersection of two linked lists Medium
#Linked List | Linked List | Medium | AmazonGoogle +1 | High | Solution → | |
| | Middle of the Linked List Easy
#Linked List | Linked List | Easy | AmazonGoogle +1 | High | Solution → | |
| | Add Two Numbers Represented in Linked List Medium
#Linked List | Linked List | Medium | AmazonGoogle +1 | High | Solution → | |
| | Linked List Cycle II Medium
#Linked List | Linked List | Medium | AmazonGoogle +1 | High | Solution → | |
| | Remove Duplicates from Sorted List Easy
#Linked List | Linked List | Easy | AmazonGoogle +1 | High | Solution → | |
| | Remove Duplicates from Sorted List - II Easy
#Linked List | Linked List | Easy | AmazonGoogle +1 | High | Solution → | |
| | Add Two Numbers II Medium
#Linked List | Linked List | Medium | AmazonGoogle +1 | High | Solution → | |
| | Odd Even Linked List Medium
#Linked List | Linked List | Medium | AmazonGoogle +1 | High | Solution → | |
| | Reverse a Linked List in groups of given size k Medium
#Linked List | Linked List | Medium | AmazonGoogle +1 | High | Solution → | |
| | Reverse Linked List II Medium
#Linked List | Linked List | Medium | AmazonGoogle +1 | High | Solution → | |
| | Convert Binary Number in a Linked List to Integer Medium
#Linked List | Linked List | Medium | AmazonGoogle +1 | High | Solution → | |
| | Partition List Medium
#Linked List | Linked List | Medium | AmazonGoogle +1 | High | Solution → | |
| | Sort List Medium
#Linked List | Linked List | Medium | AmazonGoogle +1 | High | Solution → | |
| | Next Largest Element to Right Medium
#Stack | Stack | Medium | AmazonGoogle +1 | High | Solution → | |
| | Next Largest Element to Left Medium
#Stack | Stack | Medium | AmazonGoogle +1 | High | Solution → | |
| | Next Smallest Element to Left Medium
#Stack | Stack | Medium | AmazonGoogle +1 | High | Solution → | |
| | Next Smallest Element to Right Medium
#Stack | Stack | Medium | AmazonGoogle +1 | High | Solution → | |
| | Stock Span Problem Medium
#Stack | Monotonic Stack | Medium | AmazonGoogle +1 | High | Solution → | |
| | Maximum Area Rectangle in Binary Matrix Medium
#Stack | Stack | Medium | AmazonGoogle +1 | High | Solution → | |
| | Minimum Element in Stack with Extra Space Medium
#Stack | Stack | Medium | AmazonGoogle +1 | High | Solution → | |
| | Minimum Element in Stack in O Medium
#Stack | Stack | Medium | AmazonGoogle +1 | High | Solution → | |
| | Implement Queue using Stack Medium
#Stack | Stack | Medium | AmazonGoogle +1 | High | Solution → | |
| | Implement Stack using Queues Medium
#Stack | Stack | Medium | AmazonGoogle +1 | High | Solution → | |
| | Remove All Occurrences of a Substring Medium
#Stack | Stack | Medium | AmazonGoogle +1 | High | Solution → | |
| | Minimum invalid parentheses to remove to make valid parentheses Easy
#Stack | Stack | Easy | AmazonGoogle +1 | High | Solution → | |
| | Minimum Add to Make Parentheses Valid Medium
#Stack | Stack | Medium | AmazonGoogle +1 | High | Solution → | |
| | Next Greatest Element in Sorted Array Medium
#Binary Search | Binary Search | Medium | AmazonGoogle +1 | High | Solution → | |
| | Next Smallest Element in Sorted Array Medium
#Binary Search | Binary Search | Medium | AmazonGoogle +1 | High | Solution → | |
| | Binary Search on Sorted Array Medium
#Binary Search | Binary Search | Medium | AmazonGoogle +1 | High | Solution → | |
| | Find the First and Last Occurrence of the Element in the Sorted Array Medium
#Binary Search | Binary Search | Medium | AmazonGoogle +1 | High | Solution → | |
| | Count the number of occurrences of the element in a sorted array. Medium
#Binary Search | Binary Search | Medium | AmazonGoogle +1 | High | Solution → | |
| | Search in Rotated Sorted Array II Medium
#Binary Search | Binary Search | Medium | AmazonGoogle +1 | High | Solution → | |
| | Search in a Nearly Sorted Array Medium
#Binary Search | Binary Search | Medium | AmazonGoogle +1 | High | Solution → | |
| | Single Element in a Sorted Array Medium
#Binary Search | Binary Search | Medium | AmazonGoogle +1 | High | Solution → | |
| | Find Floor of an Element in a Sorted Array Medium
#Binary Search | Binary Search | Medium | AmazonGoogle +1 | High | Solution → | |
| | Find Ciel of an Element in a Sorted Array Medium
#Binary Search | Binary Search | Medium | AmazonGoogle +1 | High | Solution → | |
| | Next Alphabetical Element in Sorted Array of Characters Medium
#Binary Search | Binary Search | Medium | AmazonGoogle +1 | High | Solution → | |
| | Find the position of an element in an infinite sorted array. Medium
#Binary Search | Binary Search | Medium | AmazonGoogle +1 | High | Solution → | |
| | Index of the first 1 in a Infinite Binary Sorted Array Medium
#Binary Search | Binary Search | Medium | AmazonGoogle +1 | High | Solution → | |
| | Minimum Difference Element in a Sorted Array Medium
#Binary Search | Binary Search | Medium | AmazonGoogle +1 | High | Solution → | |
| | Find Maximum element in Bitonic Array Medium
#Binary Search | Binary Search | Medium | AmazonGoogle +1 | High | Solution → | |
| | Search an Element in Bitonic Array Medium
#Binary Search | Binary Search | Medium | AmazonGoogle +1 | High | Solution → | |
| | Search Insert Position Medium
#Binary Search | Binary Search | Medium | AmazonGoogle +1 | High | Solution → | |
| | Pow(x, n) Medium
#Binary Search | Binary Search | Medium | AmazonGoogle +1 | High | Solution → | |
| | Smallest Missing Number in sorted array Medium
#Binary Search | Binary Search | Medium | AmazonGoogle +1 | High | Solution → | |
| | First Bad Version Medium
#Binary Search | Binary Search | Medium | AmazonGoogle +1 | High | Solution → | |
| | Row with Maximum number of 1's Medium
#Binary Search | Binary Search | Medium | AmazonGoogle +1 | High | Solution → | |