All Easy Medium Hard Very Hard
All Solved Unsolved
All topics Arrays BFS Backtracking Binary Search Binary Search Trees Binary Trees Binary search Bit manipulation Collections Counting DFS DP Divide and Conquer Dynamic Programming Famous Algorithms Graphs Greedy Hash Table HashMap HashSet Heaps Idioms Intervals Linked Lists Maps Math Matrix Monotonic deque Overflow Prefix Prefix Sum Quickselect Recursion Simulation Sliding window Sorting Stack Strings Trees Tries Two Pointers Two pointers groupBy groupingBy 130 shown
Meta — Top Interview 28 Two Sum Easy · HashMap, Arrays Longest Substring Without Repeats Medium · Sliding window Balanced Brackets Easy · Stack Best Time to Buy and Sell Stock Easy · Sliding window, Greedy Contains Nearby Duplicate Easy · Sliding window, HashSet Minimum Window Substring Hard · Sliding window, HashMap Roman to Integer Easy · Strings, Maps Longest Common Prefix Easy · Strings Find the Index of the First Occurrence Easy · Strings, Two pointers Climbing Stairs Easy · DP Single Number Easy · Bit manipulation Contains Duplicate Easy · HashSet Move Zeroes Easy · Two pointers Binary Search Easy · Binary search Rotate String Easy · Strings, Idioms Reverse Integer Medium · Math, Overflow Container With Most Water Medium · Two pointers, Greedy 3Sum Medium · Two pointers, Sorting Next Permutation Medium · Arrays, Math Search in Rotated Sorted Array Medium · Binary search Combination Sum Medium · Backtracking Subsets Medium · Bit manipulation, Backtracking Group Shifted Strings Medium · groupBy, Strings Subarray Product Less Than K Medium · Sliding window Two Non-overlapping Sub-arrays Each With Target Sum Medium · Sliding window, DP Median of Two Sorted Arrays Hard · Binary search Trapping Rain Water Hard · Two pointers Distinct Subsequences Hard · DP
Karat 12 Two Sum Easy · HashMap, Arrays Check if Every Row and Column Contains All Numbers Easy · Arrays, Hash Table, Matrix Find Words That Can Be Formed by Characters Easy · Arrays, Hash Table, Strings Ransom Note Easy · Hash Table, Strings, Counting Valid Sudoku Medium · Arrays, Hash Table, Matrix Word Search Medium · Arrays, Strings, Backtracking Alert Using Same Key-Card Three or More Times in a One Hour Period Medium · Arrays, Hash Table, Strings, Sorting Maximal Square Medium · Arrays, Dynamic Programming, Matrix Jump Game Medium · Arrays, Dynamic Programming, Greedy Find Players With Zero or One Losses Medium · Arrays, Hash Table, Sorting High-Access Employees Medium · Arrays, Hash Table, Strings, Sorting Text Justification Hard · Arrays, Strings, Simulation
Sliding Window 6 Maximum Average Subarray Easy · Sliding window Fruit Into Baskets Medium · Sliding window, HashMap Longest Repeating Character Replacement Medium · Sliding window, Counting Permutation in String Medium · Sliding window, Counting Sliding Window Maximum Hard · Sliding window, Monotonic deque Minimum K-Bit Flips Hard · Sliding window, Greedy
Dynamic Programming 16 Max Subset Sum No Adjacent Medium · DP, Arrays Number Of Ways To Make Change Medium · DP Min Number Of Coins For Change Medium · DP Levenshtein Distance Medium · DP, Strings Number Of Ways To Traverse Graph Medium · DP, Math Max Sum Increasing Subsequence Hard · DP, Arrays Longest Common Subsequence Hard · DP, Strings Min Number Of Jumps Hard · DP, Greedy Water Area Hard · DP, Arrays Knapsack Problem Hard · DP Disk Stacking Hard · DP, Sorting Numbers In Pi Hard · DP, Strings, Recursion Maximum Sum Submatrix Hard · DP, Matrix Maximize Expression Hard · DP, Arrays Dice Throws Hard · DP Juice Bottling Hard · DP
AlgoExpert — Easy 17 Validate Subsequence Easy · Arrays, Two Pointers Sorted Squared Array Easy · Arrays, Two Pointers Tournament Winner Easy · HashMap, Strings Non-Constructible Change Easy · Greedy, Sorting Transpose Matrix Easy · Matrix Nth Fibonacci Easy · Dynamic Programming, Math Product Sum Easy · Recursion Find Three Largest Numbers Easy · Arrays Caesar Cipher Encryptor Easy · Strings, Math Run-Length Encoding Easy · Strings First Non-Repeating Character Easy · Strings, HashMap Semordnilap Easy · Strings, HashSet Branch Sums Easy · Binary Trees, Recursion Node Depths Easy · Binary Trees, Recursion Depth-first Search Easy · Graphs, Recursion Find Closest Value In BST Easy · Binary Search Trees Remove Duplicates From Linked List Easy · Linked Lists
AlgoExpert — Medium 26 Three Number Sum Medium · Two Pointers, Sorting Smallest Difference Medium · Two Pointers, Sorting Move Element To End Medium · Two Pointers, Arrays Monotonic Array Medium · Arrays Spiral Traverse Medium · Matrix Longest Peak Medium · Arrays Array Of Products Medium · Arrays, Prefix First Duplicate Value Medium · Arrays, HashSet Merge Overlapping Intervals Medium · Sorting, Intervals Zero Sum Subarray Medium · Prefix Sum, HashSet Kadane's Algorithm Medium · Dynamic Programming, Arrays Balanced Brackets Medium · Stack, Strings Sunset Views Medium · Stack, Arrays Valid Starting City Medium · Greedy, Arrays BST Traversal Medium · Binary Search Trees, Recursion Validate BST Medium · Binary Search Trees, Recursion Invert Binary Tree Medium · Binary Trees, BFS Binary Tree Diameter Medium · Binary Trees, Recursion Remove Kth Node From End Medium · Linked Lists, Two Pointers Sum of Linked Lists Medium · Linked Lists, Math River Sizes Medium · Graphs, Matrix, DFS Youngest Common Ancestor Medium · Graphs, Trees Single Cycle Check Medium · Arrays, Graphs Breadth-first Search Medium · Graphs, BFS Cycle In Graph Medium · Graphs, DFS Suffix Trie Construction Medium · Tries, Strings
AlgoExpert — Hard 15 Four Number Sum Hard · HashMap, Arrays Subarray Sort Hard · Arrays Largest Range Hard · HashSet, Arrays Min Rewards Hard · Greedy, Arrays Zigzag Traverse Hard · Matrix Shifted Binary Search Hard · Binary Search Search For Range Hard · Binary Search Quickselect Hard · Quickselect, Sorting Max Path Sum In Binary Tree Hard · Binary Trees, Recursion Find Nodes Distance K Hard · Binary Trees, BFS, Graphs Lowest Common Manager Hard · Graphs, Recursion Boggle Board Hard · Tries, Graphs, Matrix Dijkstra's Algorithm Hard · Graphs, Famous Algorithms, Heaps Topological Sort Hard · Graphs, Famous Algorithms Knuth-Morris-Pratt Algorithm Hard · Strings, Famous Algorithms
AlgoExpert — Very Hard 8 Merge Sort Very Hard · Sorting, Divide and Conquer Count Inversions Very Hard · Divide and Conquer, Sorting Longest Balanced Substring Very Hard · Stack, Strings Max Profit With K Transactions Very Hard · Dynamic Programming All Kinds Of Node Depths Very Hard · Binary Trees, Recursion Right Sibling Tree Very Hard · Binary Trees, Recursion Iterative In-order Traversal Very Hard · Binary Trees, Two Pointers Flatten Binary Tree Very Hard · Binary Trees, Linked Lists
Warm-ups 3 Reverse Words Easy · Strings, Idioms Group Anagrams Medium · groupBy, Collections Top K Frequent Words Medium · groupingBy, Sorting