Striver's A2Z DSA Sheet

Striver’s A2Z is the most complete free resource of the group, and the right choice if you are genuinely starting from zero. It begins with language basics and sorting — material every other sheet assumes — and only reaches interview-shaped problems around step 9.

That completeness has a cost: 455 problems is a several-month commitment, and a meaningful fraction of them are there for teaching rather than because they get asked. Do not treat finishing it as a prerequisite for interviewing.

Use it if you have months rather than weeks, or if the other sheets have been skipping over things you do not actually know yet.

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Striver's A2Z DSA Sheet

by Raj Vikramaditya (Striver) · original sheet

455 problems

The most complete free sheet, and the best choice if you are starting from zero rather than topping up. 455 problems across 18 steps, each with a video.

How this one is mapped. Striver's A2Z DSA Sheet publishes steps rather than a LeetCode-only problem list, and a good number of its problems live on GeeksforGeeks or Coding Ninjas rather than LeetCode. So each step below is matched to the pages on this site that teach it, and the problems shown are this site's LeetCode equivalents for that step — close to the original, not identical to it. Follow the link above for the canonical list.

435 problems

86 easy277 medium72 hard

AllEasyMediumHard

Unsolved onlyExportImportReset

▾Important sorting techniques · 66

• ○21Merge Two Sorted Listseasyamazonmicrosoftapplebloomberg
• ○1051Height Checkereasy
• ○147Insertion Sort Listmedium
• ○912Sort an Arraymedium
• ○315Count of Smaller Numbers After Selfhard
• ○493Reverse Pairshard

▾Arrays: easy to hard · 3030

• ○1Two Sumeasyamazongooglemetamicrosoftapplebloomberg
• ○121Best Time to Buy and Sell Stockeasyamazonmetamicrosoftbloomberg
• ○169Majority Elementeasy
• ○268Missing Numbereasy
• ○303Range Sum Query - Immutableeasy
• ○448Find All Numbers Disappeared in an Arrayeasy
• ○766Toeplitz Matrixeasy
• ○867Transpose Matrixeasy
• ○53Maximum Subarraymediumamazonmicrosoftbloombergapple
• ○75Sort Colorsmediumamazonmicrosoftmeta
• ○238Product of Array Except Selfmediumamazonmetamicrosoftapple
• ○36Valid Sudokumedium
• ○48Rotate Imagemedium
• ○54Spiral Matrixmedium
• ○59Spiral Matrix IImedium
• ○73Set Matrix Zeroesmedium
• ○152Maximum Product Subarraymedium
• ○189Rotate Arraymedium
• ○274H-Indexmedium
• ○287Find the Duplicate Numbermedium
• ○289Game of Lifemedium
• ○304Range Sum Query 2D - Immutablemedium
• ○498Diagonal Traversemedium
• ○525Contiguous Arraymedium
• ○560Subarray Sum Equals Kmedium
• ○918Maximum Sum Circular Subarraymedium
• ○1749Maximum Absolute Sum of Any Subarraymedium
• ○2606Find the Substring With Maximum Costmedium
• ○41First Missing Positivehard
• ○135Candyhard

▾Binary search: 1D, 2D, search space · 2323

• ○35Search Insert Positioneasy
• ○69Sqrt(x)easy
• ○704Binary Searcheasy
• ○33Search in Rotated Sorted Arraymediumamazonmetamicrosoftbloomberg
• ○347Top K Frequent Elementsmediumamazonmetauberbytedance
• ○875Koko Eating Bananasmediumgoogleamazonbytedance
• ○34Find First and Last Position of Element in Sorted Arraymedium
• ○74Search a 2D Matrixmedium
• ○81Search in Rotated Sorted Array IImedium
• ○153Find Minimum in Rotated Sorted Arraymedium
• ○162Find Peak Elementmedium
• ○215Kth Largest Element in an Arraymedium
• ○240Search a 2D Matrix IImedium
• ○324Wiggle Sort IImedium
• ○692Top K Frequent Wordsmedium
• ○852Peak Index in a Mountain Arraymedium
• ○973K Closest Points to Originmedium
• ○981Time Based Key-Value Storemedium
• ○1011Capacity To Ship Packages Within D Daysmedium
• ○1631Path With Minimum Effortmedium
• ○154Find Minimum in Rotated Sorted Array IIhard
• ○410Split Array Largest Sumhard
• ○774Minimize Max Distance to Gas Stationpremiumhard

▾Strings: basic and medium · 2828

• ○242Valid Anagrameasyamazonmetabloomberg
• ○9Palindrome Numbereasy
• ○13Roman to Integereasy
• ○14Longest Common Prefixeasy
• ○58Length of Last Wordeasy
• ○125Valid Palindromeeasy
• ○169Majority Elementeasy
• ○205Isomorphic Stringseasy
• ○234Palindrome Linked Listeasy
• ○290Word Patterneasy
• ○383Ransom Noteeasy
• ○387First Unique Character in a Stringeasy
• ○680Valid Palindrome IIeasy
• ○49Group Anagramsmediumamazonmetauberbloomberg
• ○5Longest Palindromic Substringmedium
• ○12Integer to Romanmedium
• ○131Palindrome Partitioningmedium
• ○151Reverse Words in a Stringmedium
• ○271Encode and Decode Stringspremiummedium
• ○274H-Indexmedium
• ○438Find All Anagrams in a Stringmedium
• ○451Sort Characters By Frequencymedium
• ○516Longest Palindromic Subsequencemedium
• ○647Palindromic Substringsmedium
• ○1657Determine if Two Strings Are Closemedium
• ○132Palindrome Partitioning IIhard
• ○135Candyhard
• ○1312Minimum Insertion Steps to Make a String Palindromehard

▾Linked list · 2323

• ○206Reverse Linked Listeasyamazonmicrosoftapplebloombergmeta
• ○21Merge Two Sorted Listseasyamazonmicrosoftapplebloomberg
• ○141Linked List Cycleeasyamazonmicrosoftbloomberg
• ○83Remove Duplicates from Sorted Listeasy
• ○202Happy Numbereasy
• ○876Middle of the Linked Listeasy
• ○133Clone Graphmediummetagoogleamazon
• ○138Copy List with Random Pointermediumamazonmicrosoftbloombergapple
• ○143Reorder Listmediumamazonmetabloomberg
• ○2Add Two Numbersmedium
• ○19Remove Nth Node From End of Listmedium
• ○24Swap Nodes in Pairsmedium
• ○61Rotate Listmedium
• ○82Remove Duplicates from Sorted List IImedium
• ○86Partition Listmedium
• ○92Reverse Linked List IImedium
• ○142Linked List Cycle IImedium
• ○148Sort Listmedium
• ○287Find the Duplicate Numbermedium
• ○328Odd Even Linked Listmedium
• ○426Convert Binary Search Tree to Sorted Doubly Linked Listpremiummedium
• ○430Flatten a Multilevel Doubly Linked Listmedium
• ○25Reverse Nodes in k-Grouphard

▾Recursion: pattern-wise · 2424

• ○108Convert Sorted Array to Binary Search Treeeasy
• ○17Letter Combinations of a Phone Numbermedium
• ○22Generate Parenthesesmedium
• ○31Next Permutationmedium
• ○39Combination Summedium
• ○40Combination Sum IImedium
• ○46Permutationsmedium
• ○47Permutations IImedium
• ○77Combinationsmedium
• ○78Subsetsmedium
• ○79Word Searchmedium
• ○90Subsets IImedium
• ○148Sort Listmedium
• ○241Different Ways to Add Parenthesesmedium
• ○427Construct Quad Treemedium
• ○556Next Greater Element IIImedium
• ○784Letter Case Permutationmedium
• ○912Sort an Arraymedium
• ○4Median of Two Sorted Arrayshardgoogleamazonmicrosoftbytedance
• ○37Sudoku Solverhard
• ○51N-Queenshard
• ○52N-Queens IIhard
• ○60Permutation Sequencehard
• ○315Count of Smaller Numbers After Selfhard

▾Bit manipulation · 1515

• ○67Add Binaryeasy
• ○136Single Numbereasy
• ○190Reverse Bitseasy
• ○191Number of 1 Bitseasy
• ○268Missing Numbereasy
• ○338Counting Bitseasy
• ○1720Decode XORed Arrayeasy
• ○78Subsetsmedium
• ○137Single Number IImedium
• ○201Bitwise AND of Numbers Rangemedium
• ○260Single Number IIImedium
• ○371Sum of Two Integersmedium
• ○421Maximum XOR of Two Numbers in an Arraymedium
• ○600Non-negative Integers without Consecutive Oneshard
• ○1483Kth Ancestor of a Tree Nodehard

▾Stacks and queues · 2929

• ○20Valid Parentheseseasyamazongooglemetamicrosoftbloomberg
• ○225Implement Stack using Queueseasy
• ○232Implement Queue using Stackseasy
• ○496Next Greater Element Ieasy
• ○1047Remove All Adjacent Duplicates In Stringeasy
• ○739Daily Temperaturesmediumamazonmetabloomberg
• ○71Simplify Pathmedium
• ○150Evaluate Reverse Polish Notationmedium
• ○155Min Stackmedium
• ○227Basic Calculator IImedium
• ○394Decode Stringmedium
• ○503Next Greater Element IImedium
• ○622Design Circular Queuemedium
• ○641Design Circular Dequemedium
• ○678Valid Parenthesis Stringmedium
• ○853Car Fleetmedium
• ○907Sum of Subarray Minimumsmedium
• ○921Minimum Add to Make Parentheses Validmedium
• ○1381Design a Stack With Increment Operationmedium
• ○1438Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limitmedium
• ○1696Jump Game VImedium
• ○2762Continuous Subarraysmedium
• ○42Trapping Rain Waterhardamazongooglemetabloomberg
• ○84Largest Rectangle in Histogramhardgoogleamazonbytedance
• ○239Sliding Window Maximumhardamazongooglebytedance
• ○32Longest Valid Parentheseshard
• ○224Basic Calculatorhard
• ○862Shortest Subarray with Sum at Least Khard
• ○1499Max Value of Equationhard

▾Sliding window and two pointer · 3737

• ○26Remove Duplicates from Sorted Arrayeasy
• ○27Remove Elementeasy
• ○88Merge Sorted Arrayeasy
• ○125Valid Palindromeeasy
• ○219Contains Duplicate IIeasy
• ○283Move Zeroeseasy
• ○392Is Subsequenceeasy
• ○643Maximum Average Subarray Ieasy
• ○3Longest Substring Without Repeating Charactersmediumamazongooglemetamicrosoftbloomberg
• ○153Summediumamazonmetamicrosoftapplebloomberg
• ○11Container With Most Watermediumamazonmetabloomberg
• ○80Remove Duplicates from Sorted Array IImedium
• ○167Two Sum II - Input Array Is Sortedmedium
• ○209Minimum Size Subarray Summedium
• ○340Longest Substring with At Most K Distinct Characterspremiummedium
• ○424Longest Repeating Character Replacementmedium
• ○437Path Sum IIImedium
• ○438Find All Anagrams in a Stringmedium
• ○523Continuous Subarray Summedium
• ○525Contiguous Arraymedium
• ○560Subarray Sum Equals Kmedium
• ○567Permutation in Stringmedium
• ○904Fruit Into Basketsmedium
• ○930Binary Subarrays With Summedium
• ○974Subarray Sums Divisible by Kmedium
• ○1004Max Consecutive Ones IIImedium
• ○1248Count Number of Nice Subarraysmedium
• ○1456Maximum Number of Vowels in a Substring of Given Lengthmedium
• ○1493Longest Subarray of 1's After Deleting One Elementmedium
• ○1838Frequency of the Most Frequent Elementmedium
• ○2461Maximum Sum of Distinct Subarrays With Length Kmedium
• ○42Trapping Rain Waterhardamazongooglemetabloomberg
• ○76Minimum Window Substringhardmetaamazongoogleuber
• ○30Substring with Concatenation of All Wordshard
• ○220Contains Duplicate IIIhard
• ○992Subarrays with K Different Integershard
• ○1074Number of Submatrices That Sum to Targethard

▾Heaps · 1616

• ○1046Last Stone Weighteasy
• ○347Top K Frequent Elementsmediumamazonmetauberbytedance
• ○621Task Schedulermediummetaamazonuber
• ○215Kth Largest Element in an Arraymedium
• ○373Find K Pairs with Smallest Sumsmedium
• ○378Kth Smallest Element in a Sorted Matrixmedium
• ○451Sort Characters By Frequencymedium
• ○973K Closest Points to Originmedium
• ○1962Remove Stones to Minimize the Totalmedium
• ○2542Maximum Subsequence Scoremedium
• ○295Find Median from Data Streamhardamazongooglemetabloomberg
• ○23Merge k Sorted Listshard
• ○480Sliding Window Medianhard
• ○502IPOhard
• ○632Smallest Range Covering Elements from K Listshard
• ○1851Minimum Interval to Include Each Queryhard

▾Greedy algorithms · 3333

• ○228Summary Rangeseasy
• ○252Meeting Roomspremiumeasy
• ○56Merge Intervalsmediumgooglemetaamazonuberbloomberg
• ○621Task Schedulermediummetaamazonuber
• ○45Jump Game IImedium
• ○55Jump Gamemedium
• ○57Insert Intervalmedium
• ○122Best Time to Buy and Sell Stock IImedium
• ○134Gas Stationmedium
• ○179Largest Numbermedium
• ○253Meeting Rooms IIpremiummedium
• ○406Queue Reconstruction by Heightmedium
• ○435Non-overlapping Intervalsmedium
• ○452Minimum Number of Arrows to Burst Balloonsmedium
• ○646Maximum Length of Pair Chainmedium
• ○678Valid Parenthesis Stringmedium
• ○692Top K Frequent Wordsmedium
• ○731My Calendar IImedium
• ○763Partition Labelsmedium
• ○846Hand of Straightsmedium
• ○853Car Fleetmedium
• ○937Reorder Data in Log Filesmedium
• ○1024Video Stitchingmedium
• ○1029Two City Schedulingmedium
• ○1094Car Poolingmedium
• ○1306Jump Game IIImedium
• ○1899Merge Triplets to Form Target Tripletmedium
• ○2406Divide Intervals Into Minimum Number of Groupsmedium
• ○218The Skyline Problemhard
• ○354Russian Doll Envelopeshard
• ○732My Calendar IIIhard
• ○759Employee Free Timepremiumhard
• ○1851Minimum Interval to Include Each Queryhard

▾Binary trees · 4747

• ○94Binary Tree Inorder Traversaleasy
• ○100Same Treeeasy
• ○101Symmetric Treeeasy
• ○104Maximum Depth of Binary Treeeasy
• ○110Balanced Binary Treeeasy
• ○111Minimum Depth of Binary Treeeasy
• ○112Path Sumeasy
• ○222Count Complete Tree Nodeseasy
• ○543Diameter of Binary Treeeasy
• ○572Subtree of Another Treeeasy
• ○617Merge Two Binary Treeseasy
• ○637Average of Levels in Binary Treeeasy
• ○993Cousins in Binary Treeeasy
• ○102Binary Tree Level Order Traversalmediumamazonmetamicrosoftbytedance
• ○236Lowest Common Ancestor of a Binary Treemediummetaamazonmicrosoftapple
• ○98Validate Binary Search Treemedium
• ○103Binary Tree Zigzag Level Order Traversalmedium
• ○105Construct Binary Tree from Preorder and Inorder Traversalmedium
• ○106Construct Binary Tree from Inorder and Postorder Traversalmedium
• ○107Binary Tree Level Order Traversal IImedium
• ○113Path Sum IImedium
• ○114Flatten Binary Tree to Linked Listmedium
• ○116Populating Next Right Pointers in Each Nodemedium
• ○117Populating Next Right Pointers in Each Node IImedium
• ○129Sum Root to Leaf Numbersmedium
• ○199Binary Tree Right Side Viewmedium
• ○235Lowest Common Ancestor of a Binary Search Treemedium
• ○314Binary Tree Vertical Order Traversalpremiummedium
• ○437Path Sum IIImedium
• ○449Serialize and Deserialize BSTmedium
• ○515Find Largest Value in Each Tree Rowmedium
• ○652Find Duplicate Subtreesmedium
• ○654Maximum Binary Treemedium
• ○662Maximum Width of Binary Treemedium
• ○863All Nodes Distance K in Binary Treemedium
• ○865Smallest Subtree with all the Deepest Nodesmedium
• ○889Construct Binary Tree from Preorder and Postorder Traversalmedium
• ○958Check Completeness of a Binary Treemedium
• ○1008Construct Binary Search Tree from Preorder Traversalmedium
• ○1123Lowest Common Ancestor of Deepest Leavesmedium
• ○1161Maximum Level Sum of a Binary Treemedium
• ○1302Deepest Leaves Summedium
• ○1448Count Good Nodes in Binary Treemedium
• ○1650Lowest Common Ancestor of a Binary Tree IIIpremiummedium
• ○2096Step-By-Step Directions From a Binary Tree Node to Anothermedium
• ○297Serialize and Deserialize Binary Treehardmetaamazongooglebloomberg
• ○124Binary Tree Maximum Path Sumhard

▾Binary search trees · 1515

• ○108Convert Sorted Array to Binary Search Treeeasy
• ○110Balanced Binary Treeeasy
• ○222Count Complete Tree Nodeseasy
• ○501Find Mode in Binary Search Treeeasy
• ○530Minimum Absolute Difference in BSTeasy
• ○700Search in a Binary Search Treeeasy
• ○897Increasing Order Search Treeeasy
• ○98Validate Binary Search Treemedium
• ○173Binary Search Tree Iteratormedium
• ○230Kth Smallest Element in a BSTmedium
• ○235Lowest Common Ancestor of a Binary Search Treemedium
• ○450Delete Node in a BSTmedium
• ○538Convert BST to Greater Treemedium
• ○701Insert into a Binary Search Treemedium
• ○99Recover Binary Search Treehard

▾Graphs · 4848

• ○112Path Sumeasy
• ○463Island Perimetereasy
• ○733Flood Filleasy
• ○200Number of Islandsmediumamazongooglemetamicrosoftbytedance
• ○102Binary Tree Level Order Traversalmediumamazonmetamicrosoftbytedance
• ○207Course Schedulemediumgoogleamazonmetabytedance
• ○133Clone Graphmediummetagoogleamazon
• ○743Network Delay Timemediumgoogleuberamazon
• ○787Cheapest Flights Within K Stopsmediumgoogleuberamazon
• ○994Rotting Orangesmediumamazonmicrosoftbytedance
• ○1584Min Cost to Connect All Pointsmediumamazonuber
• ○128Longest Consecutive Sequencemedium
• ○130Surrounded Regionsmedium
• ○210Course Schedule IImedium
• ○261Graph Valid Treepremiummedium
• ○286Walls and Gatespremiummedium
• ○310Minimum Height Treesmedium
• ○323Number of Connected Components in an Undirected Graphpremiummedium
• ○399Evaluate Divisionmedium
• ○417Pacific Atlantic Water Flowmedium
• ○433Minimum Genetic Mutationmedium
• ○54201 Matrixmedium
• ○547Number of Provincesmedium
• ○684Redundant Connectionmedium
• ○695Max Area of Islandmedium
• ○721Accounts Mergemedium
• ○785Is Graph Bipartite?medium
• ○886Possible Bipartitionmedium
• ○909Snakes and Laddersmedium
• ○990Satisfiability of Equality Equationsmedium
• ○1020Number of Enclavesmedium
• ○1091Shortest Path in Binary Matrixmedium
• ○1135Connecting Cities With Minimum Costpremiummedium
• ○1136Parallel Coursespremiummedium
• ○1162As Far from Land as Possiblemedium
• ○1319Number of Operations to Make Network Connectedmedium
• ○1334Find the City With the Smallest Number of Neighbors at a Threshold Distancemedium
• ○1631Path With Minimum Effortmedium
• ○127Word Ladderhardamazongooglebytedance
• ○269Alien Dictionarypremiumhardgooglemetaamazon
• ○329Longest Increasing Path in a Matrixhard
• ○332Reconstruct Itineraryhard
• ○778Swim in Rising Waterhard
• ○1168Optimize Water Distribution in a Villagepremiumhard
• ○1192Critical Connections in a Networkhard
• ○1293Shortest Path in a Grid with Obstacles Eliminationhard
• ○1368Minimum Cost to Make at Least One Valid Path in a Gridhard
• ○2290Minimum Obstacle Removal to Reach Cornerhard

▾Dynamic programming · 4848

• ○70Climbing Stairseasy
• ○118Pascal's Triangleeasy
• ○509Fibonacci Numbereasy
• ○543Diameter of Binary Treeeasy
• ○746Min Cost Climbing Stairseasy
• ○1137N-th Tribonacci Numbereasy
• ○72Edit Distancemediumgoogleamazonmicrosoftbytedance
• ○139Word Breakmediumgoogleamazonmetabytedance
• ○300Longest Increasing Subsequencemediumgooglemicrosoftbytedanceuber
• ○322Coin Changemediumamazongooglemicrosoftbytedance
• ○1143Longest Common Subsequencemediumgoogleamazonmicrosoft
• ○5Longest Palindromic Substringmedium
• ○62Unique Pathsmedium
• ○63Unique Paths IImedium
• ○64Minimum Path Summedium
• ○91Decode Waysmedium
• ○97Interleaving Stringmedium
• ○120Trianglemedium
• ○198House Robbermedium
• ○213House Robber IImedium
• ○221Maximal Squaremedium
• ○309Best Time to Buy and Sell Stock with Cooldownmedium
• ○337House Robber IIImedium
• ○357Count Numbers with Unique Digitsmedium
• ○377Combination Sum IVmedium
• ○416Partition Equal Subset Summedium
• ○474Ones and Zeroesmedium
• ○494Target Summedium
• ○516Longest Palindromic Subsequencemedium
• ○518Coin Change IImedium
• ○583Delete Operation for Two Stringsmedium
• ○698Partition to K Equal Sum Subsetsmedium
• ○1049Last Stone Weight IImedium
• ○1696Jump Game VImedium
• ○1824Minimum Sideway Jumpsmedium
• ○10Regular Expression Matchinghard
• ○115Distinct Subsequenceshard
• ○123Best Time to Buy and Sell Stock IIIhard
• ○124Binary Tree Maximum Path Sumhard
• ○188Best Time to Buy and Sell Stock IVhard
• ○312Burst Balloonshard
• ○329Longest Increasing Path in a Matrixhard
• ○847Shortest Path Visiting All Nodeshard
• ○864Shortest Path to Get All Keyshard
• ○902Numbers At Most N Given Digit Sethard
• ○1012Numbers With Repeated Digitshard
• ○1425Constrained Subsequence Sumhard
• ○2376Count Special Integershard

▾Tries · 88

• ○208Implement Trie (Prefix Tree)mediumgoogleamazonbloomberg
• ○211Design Add and Search Words Data Structuremedium
• ○421Maximum XOR of Two Numbers in an Arraymedium
• ○648Replace Wordsmedium
• ○677Map Sum Pairsmedium
• ○720Longest Word in Dictionarymedium
• ○1268Search Suggestions Systemmedium
• ○212Word Search IIhardgoogleamazonbytedance

▾Strings: advanced · 55

• ○28Find the Index of the First Occurrence in a Stringeasy
• ○438Find All Anagrams in a Stringmedium
• ○686Repeated String Matchmedium
• ○214Shortest Palindromehard
• ○1392Longest Happy Prefixhard

Before you start this sheet

Do the consensus problems first. They are the problems every sheet author independently agreed on, so they are the highest-value problems available regardless of which sheet you eventually commit to.