📖
LeetCode
  • Introduction
  • Array
    • Best Time To Buy And Sell Stock
      • 121.Best-Time-to-Buy-and-Sell-Stock
      • 122.Best-Time-to-Buy-and-Sell-Stock-II
      • 123.Best-Time-to-Buy-and-Sell-Stock-III
      • 188.Best-Time-to-Buy-and-Sell-Stock-IV
    • 1.Two-Sum
    • 1007.Minimum-Domino-Rotations-For-Equal-Row
    • 1031.Maximum-Sum-of-Two-Non-Overlapping-Subarrays
    • 1052.Grumpy-Bookstore-Owner
    • 11.Container-With-Most-Water
    • 1122.Relative-Sort-Array
    • 1163.Last-Substring-in-Lexicographical-Order
    • [118.Pascal's-Triangle](Array/118.Pascal's-Triangle.md)
    • 1181.Before-and-After-Puzzle
    • 1231.Divide-Chocolate
    • 1296.Divide-Array-in-Sets-of-K-Consecutive-Numbers
    • 1304.Find-N-Unique-Integers-Sum-up-to-Zero
    • 134.Gas-Station
    • 135.Candy
    • 1352.Product-of-the-Last-K-Numbers
    • 136.Single-Number
    • 14.Longest-Common-Prefix
    • 1477.Find-Two-Non-overlapping-Sub-arrays-Each-With-Target-Sum
    • 15.3Sum
    • 152.Maximum-Product-Subarray
    • 16.3Sum-Closest
    • 163.Missing-Ranges
    • 169.Majority-Element
    • 18.4Sum
    • 189.Rotate-Array
    • 204.Count-Primes
    • 215.Kth-Largest-Element-in-an-Array
    • 217.Contains-Duplicate
    • 219.Contains-Duplicate-II
    • 220.Contains-Duplicate-III
    • 228.Summary-Ranges
    • 229.Majority-Element-II
    • 238.Product-of-Array-Except-Self
    • 239.Sliding-Window-Maximum
    • 243.Shortest-Word-Distance
    • 252.Meeting-Rooms
    • 266.Palindrome-Permutation
    • 268.Missing-Number
    • 273.Integer-to-English-Words
    • 279.Perfect-Squares
    • 283.Move-Zeroes
    • 287.Find-the-Duplicate-Number
    • 29.Divide-Two-Integers
    • 299.Bulls-and-Cows
    • 31.Next-Permutation
    • 325.Maximum-Size-Subarray-Sum-Equals-k
    • 334.Increasing-Triplet-Subsequence
    • 340.Longest-Substring-with-At-Most-K-Distinct-Characters
    • 347.Top-K-Frequent-Elements
    • 349.Intersection-of-Two-Arrays
    • 350.Intersection-of-Two-Arrays-II
    • 354.Russian-Doll-Envelopes
    • 367.Valid-Perfect-Square
    • 378.Kth-Smallest-Element-in-a-Sorted-Matrix
    • 38.Count-and-Say
    • 383.Ransom-Note
    • 387.First-Unique-Character-in-a-String
    • 4.Median-of-Two-Sorted-Arrays
    • 406.Queue-Reconstruction-by-Height
    • 410.Split-Array-Largest-Sum
    • 412.Fizz-Buzz
    • 419.Battleships-in-a-Board
    • 435.Non-overlapping-Intervals
    • 438.Find-All-Anagrams-in-a-String
    • 442.Find-All-Duplicates-in-an-Array
    • 457.Circular-Array-Loop
    • 509.Fibonacci-Number
    • 53.Maximum-Subarray
    • 539.Minimum-Time-Difference
    • 540.Single-Element-in-a-Sorted-Array
    • 56.Merge-Intervals
    • 560.Subarray-Sum-Equals-K
    • 57.Insert-Interval
    • 575.Distribute-Candies
    • 581.Shortest-Unsorted-Continuous-Subarray
    • 593.Valid-Square
    • 6.ZigZag-Conversion
    • 609.Find-Duplicate-File-in-System
    • 611.Valid-Triangle-Number
    • 621.Task-Scheduler
    • 628.Maximum-Product-of-Three-Numbers
    • 632.Smallest-Range-Covering-Elements-from-K-Lists
    • 659.Split-Array-into-Consecutive-Subsequences
    • 67.Add-Binary
    • 670.Maximum-Swap
    • 7.Reverse-Integer
    • 717.1-bit-and-2-bit-Characters
    • 722.Remove-Comments
    • 724.Find-Pivot-Index
    • 763.Partition-Labels
    • 811.Subdomain-Visit-Count
    • 845.Longest-Mountain-in-Array
    • 846.Hand-of-Straights
    • 862.Shortest-Subarray-with-Sum-at-Least-K
    • 866.Prime-Palindrome
    • 881.Boats-to-Save-People
    • 937.Reorder-Data-in-Log-Files
    • 953.Verifying-an-Alien-Dictionary
    • 957.Prison-Cells-After-N-Days
    • 973.K-Closest-Points-to-Origin
    • 974.Subarray-Sums-Divisible-by-K
    • 995.Minimum-Number-of-K-Consecutive-Bit-Flips
    • Interleaving Positive And Negative Numbers
    • Maximum Subarray Difference
    • Maximum Subarray Ii
    • Merge Sorted Array Ii
    • Minimum Subarray
    • Partition Array
    • Recover Rotated Sorted Array
    • Subarray Sum Closest
    • Subarray Sum Zero
  • Basic Knowledge
    • Binary Tree
    • Bit Operation
    • Heapify
    • Java Syntax
    • Monotonous Stack
    • Trie Tree
  • Binary Search
    • 1011.Capacity-To-Ship-Packages-Within-D-Days
    • 1044.Longest-Duplicate-Substring
    • 1062.Longest-Repeating-Substring
    • 153.Find-Minimum-in-Rotated-Sorted-Array
    • 162.Find-Peak-Element
    • 278.First-Bad-Version
    • 33.Search-in-Rotated-Sorted-Array
    • 34.Find-First-and-Last-Position-of-Element-in-Sorted-Array
    • 35.Search-Insert-Position
    • [50.Pow(x,-n)](Binary-Search/50.Pow(x,-n).md)
    • [69.Sqrt(x)](Binary-Search/69.Sqrt(x).md)
    • 704.Binary-Search
    • 74.Search-a-2D-Matrix
    • 785.Is-Graph-Bipartite?
    • 796.Rotate-String
    • 81.Search-in-Rotated-Sorted-Array-II
    • Count Of Smaller Number
    • Median
    • Search In A Big Sorted Array
  • Binary Tree
    • Serialize And Deserialize
      • 297.Serialize-and-Deserialize-Binary-Tree
      • 428.Serialize-and-Deserialize-N-ary-Tree
      • 449.Serialize-and-Deserialize-BST
    • 100.Same-Tree
    • 101.Symmetric-Tree
    • 1038.Binary-Search-Tree-to-Greater-Sum-Tree
    • 105.Construct-Binary-Tree-from-Preorder-and-Inorder-Traversal
    • 106.Construct-Binary-Tree-from-Inorder-and-Postorder-Traversal
    • 108.Convert-Sorted-Array-to-Binary-Search-Tree
    • 1110.Delete-Nodes-And-Return-Forest
    • 114.Flatten-Binary-Tree-to-Linked-List
    • 1145.Binary-Tree-Coloring-Game
    • 116.Populating-Next-Right-Pointers-in-Each-Node
    • 117.Populating-Next-Right-Pointers-in-Each-Node-II
    • 129.Sum-Root-to-Leaf-Numbers
    • 144.Binary-Tree-Preorder-Traversal
    • 199.Binary-Tree-Right-Side-View
    • 222.Count-Complete-Tree-Nodes
    • 226.Invert-Binary-Tree
    • 230.Kth-Smallest-Element-in-a-BST
    • 257.Binary-Tree-Paths
    • 270.Closest-Binary-Search-Tree-Value
    • 285.Inorder-Successor-in-BST
    • 337.House-Robber-III
    • 426.Convert-Binary-Search-Tree-to-Sorted-Doubly-Linked-List
    • 510.Inorder-Successor-in-BST-II
    • 543.Diameter-of-Binary-Tree
    • 617.Merge-Two-Binary-Trees
    • 652.Find-Duplicate-Subtrees
    • 653.Two-Sum-IV---Input-is-a-BST
    • 662.Maximum-Width-of-Binary-Tree
    • 669.Trim-a-Binary-Search-Tree
    • 889.Construct-Binary-Tree-from-Preorder-and-Postorder-Traversal
    • 938.Range-Sum-of-BST
    • 94.Binary-Tree-Inorder-Traversal
    • 951.Flip-Equivalent-Binary-Trees
    • 958.Check-Completeness-of-a-Binary-Tree
    • 979.Distribute-Coins-in-Binary-Tree
    • 987.Vertical-Order-Traversal-of-a-Binary-Tree
    • Search Range In Binary Search Tree
  • Bit
    • 307.Range-Sum-Query---Mutable
    • 308.Range-Sum-Query-2D---Mutable
    • 315.Count-of-Smaller-Numbers-After-Self
    • 493.Reverse-Pairs
  • Data Structure
    • Basic Calculator
      • 224.Basic-Calculator
      • 227.Basic-Calculator-II
      • 772.Basic-Calculator-III
      • Basic Claculator Iv
    • 1146.Snapshot-Array
    • 1152.Analyze-User-Website-Visit-Pattern
    • 1167.Minimum-Cost-to-Connect-Sticks
    • 1172.Dinner-Plate-Stacks
    • 1236.Web-Crawler
    • 128.Longest-Consecutive-Sequence
    • 146.LRU-Cache
    • 155.Min-Stack
    • 158.Read-N-Characters-Given-Read4-II---Call-multiple-times
    • 225.Implement-Stack-using-Queues
    • 232.Implement-Queue-using-Stacks
    • 253.Meeting-Rooms-II
    • 263.Ugly-Number
    • 271.Encode-and-Decode-Strings
    • [28.Implement-strStr()](Data-Structure/28.Implement-strStr().md)
    • 281.Zigzag-Iterator
    • 284.Peeking-Iterator
    • 295.Find-Median-from-Data-Stream
    • 314.Binary-Tree-Vertical-Order-Traversal
    • 332.Reconstruct-Itinerary
    • 341.Flatten-Nested-List-Iterator
    • 346.Moving-Average-from-Data-Stream
    • 348.Design-Tic-Tac-Toe
    • 353.Design-Snake-Game
    • 359.Logger-Rate-Limiter
    • 362.Design-Hit-Counter
    • [380.Insert-Delete-GetRandom-O(1)](Data-Structure/380.Insert-Delete-GetRandom-O(1).md)
    • [381.Insert-Delete-GetRandom-O(1)---Duplicates-allowed](Data-Structure/381.Insert-Delete-GetRandom-O
    • 384.Shuffle-an-Array
    • 41.First-Missing-Positive
    • 460.LFU-Cache
    • [470.Implement-Rand10()-Using-Rand7()](Data-Structure/470.Implement-Rand10()-Using-Rand7().md)
    • 49.Group-Anagrams
    • 523.Continuous-Subarray-Sum
    • 528.Random-Pick-with-Weight
    • 535.Encode-and-Decode-TinyURL
    • 545.Boundary-of-Binary-Tree
    • 572.Subtree-of-Another-Tree
    • 588.Design-In-Memory-File-System
    • 622.Design-Circular-Queue
    • 642.Design-Search-Autocomplete-System
    • 692.Top-K-Frequent-Words
    • 706.Design-HashMap
    • 707.Design-Linked-List
    • 729.My-Calendar-I
    • 731.My-Calendar-II
    • 759.Employee-Free-Time
    • 794.Valid-Tic-Tac-Toe-State
    • 84.Largest-Rectangle-in-Histogram
    • 843.Guess-the-Word
    • 900.RLE-Iterator
    • 937.Reorder-Data-in-Log-Files
    • 981.Time-Based-Key-Value-Store
    • 99.Recover-Binary-Search-Tree
    • Add And Search Word Data Structure Design
    • Heapify
    • Max Tree
    • Rehashing
    • Subarray Sum Zero
  • Divide Conquer
    • 102.Binary-Tree-Level-Order-Traversal
    • 103.Binary-Tree-Zigzag-Level-Order-Traversal
    • 104.Maximum-Depth-of-Binary-Tree
    • 107.Binary-Tree-Level-Order-Traversal-II
    • 110.Balanced-Binary-Tree
    • 124.Binary-Tree-Maximum-Path-Sum
    • 173.Binary-Search-Tree-Iterator
    • 218.The-Skyline-Problem
    • 236.Lowest-Common-Ancestor-of-a-Binary-Tree
    • 450.Delete-Node-in-a-BST
    • 973.K-Closest-Points-to-Origin
    • 98.Validate-Binary-Search-Tree
    • Inorder
    • Insert Node In A Binary Search Tree
    • Postorder
    • Preorder
  • Dynamic Programming
    • 1.position
      • 1048.Longest-String-Chain
      • 198.House-Robber
      • 256.Paint-House
      • 265.Paint-House-II
      • 32.Longest-Valid-Parentheses
      • 338.Counting-Bits
      • 361.Bomb-Enemy
      • 403.Frog-Jump
      • 45.Jump-Game-II
      • 518.Coin-Change-2
      • 55.Jump-Game
      • 62.Unique-Paths
      • 63.Unique-Paths-II
      • 64.Minimum-Path-Sum
      • 70.Climbing-Stairs
      • 72.Edit-Distance
      • 85.Maximal-Rectangle
      • 871.Minimum-Number-of-Refueling-Stops
      • 91.Decode-Ways
      • 97.Interleaving-String
      • 980.Unique-Paths-III
    • 2.sequence
      • Sell Stock
        • 188.Best-Time-to-Buy-and-Sell-Stock-IV
        • 309.Best-Time-to-Buy-and-Sell-Stock-with-Cooldown
      • 115.Distinct-Subsequences
      • 132.Palindrome-Partitioning-II
      • 300.Longest-Increasing-Subsequence
      • 472.Concatenated-Words
      • 516.Longest-Palindromic-Subsequence
      • 727.Minimum-Window-Subsequence
      • 801.Minimum-Swaps-To-Make-Sequences-Increasing
      • K Sum
      • Long Common Sequence
      • Maximum Subarray Iii
      • Minimum Adjustment Cost
    • Backpack Problem
      • 1155.Number-of-Dice-Rolls-With-Target-Sum
      • 322.Coin-Change
      • 416.Partition-Equal-Subset-Sum
      • Backpack Ii
      • Backpack Iii
      • Backpack
    • 区间型
      • 1000.Minimum-Cost-to-Merge-Stones
      • 1335.Minimum-Difficulty-of-a-Job-Schedule
      • 375.Guess-Number-Higher-or-Lower-II
      • 87.Scramble-String
      • Coins In A Line Iii
    • 矩阵坐标
      • 1277.Count-Square-Submatrices-with-All-Ones
      • 221.Maximal-Square
      • 741.Cherry-Pickup
    • 1049.Last-Stone-Weight-II
    • 1140.Stone-Game-II
    • 1235.Maximum-Profit-in-Job-Scheduling
    • 1320.Minimum-Distance-to-Type-a-Word-Using-Two-Fingers
    • 1406.Stone-Game-III
    • 774.Minimize-Max-Distance-to-Gas-Station
    • Longest Arithmetic Sequence
  • Graph Search
    • Word Ladder
      • 126.Word-Ladder-II
      • 127.Word-Ladder
    • 10.Regular-Expression-Matching
    • 1041.Robot-Bounded-In-Circle
    • 1066.Campus-Bikes-II
    • 1087.Brace-Expansion
    • 1102.Path-With-Maximum-Minimum-Value
    • 113.Path-Sum-II
    • 1192.Critical-Connections-in-a-Network
    • 1197.Minimum-Knight-Moves
    • 1219.Path-with-Maximum-Gold
    • 1239.Maximum-Length-of-a-Concatenated-String-with-Unique-Characters
    • 1284.Minimum-Number-of-Flips-to-Convert-Binary-Matrix-to-Zero-Matrix
    • 1293.Shortest-Path-in-a-Grid-with-Obstacles-Elimination
    • 131.Palindrome-Partitioning
    • 133.Clone-Graph
    • 1345.Jump-Game-IV
    • 1376.Time-Needed-to-Inform-All-Employees
    • 139.Word-Break
    • 140.Word-Break-II
    • 1416.Restore-The-Array
    • 17.Letter-Combinations-of-a-Phone-Number
    • 179.Largest-Number
    • 200.Number-of-Islands
    • 212.Word-Search-II
    • 22.Generate-Parentheses
    • 248.Strobogrammatic-Number-III
    • 286.Walls-and-Gates
    • 289.Game-of-Life
    • 298.Binary-Tree-Longest-Consecutive-Sequence
    • 301.Remove-Invalid-Parentheses
    • 312.Burst-Balloons
    • 317.Shortest-Distance-from-All-Buildings
    • 320.Generalized-Abbreviation
    • 323.Number-of-Connected-Components-in-an-Undirected-Graph
    • 329.Longest-Increasing-Path-in-a-Matrix
    • 364.Nested-List-Weight-Sum-II
    • 386.Lexicographical-Numbers
    • 39.Combination-Sum
    • 399.Evaluate-Division
    • 40.Combination-Sum-II
    • 417.Pacific-Atlantic-Water-Flow
    • 430.Flatten-a-Multilevel-Doubly-Linked-List
    • 437.Path-Sum-III
    • 44.Wildcard-Matching
    • 463.Island-Perimeter
    • 465.Optimal-Account-Balancing
    • 489.Robot-Room-Cleaner
    • 490.The-Maze
    • 494.Target-Sum
    • 51.N-Queens
    • 515.Find-Largest-Value-in-Each-Tree-Row
    • 524.Longest-Word-in-Dictionary-through-Deleting
    • 529.Minesweeper
    • 547.Number-of-Provinces
    • 568.Maximum-Vacation-Days
    • 675.Cut-Off-Trees-for-Golf-Event
    • 679.24-Game
    • 695.Max-Area-of-Island
    • 698.Partition-to-K-Equal-Sum-Subsets
    • 721.Accounts-Merge
    • 733.Flood-Fill
    • 737.Sentence-Similarity-II
    • 743.Network-Delay-Time
    • 752.Open-the-Lock
    • 753.Cracking-the-Safe
    • 773.Sliding-Puzzle
    • 79.Word-Search
    • 802.Find-Eventual-Safe-States
    • 815.Bus-Routes
    • 818.Race-Car
    • 854.K-Similar-Strings
    • 863.All-Nodes-Distance-K-in-Binary-Tree
    • 864.Shortest-Path-to-Get-All-Keys
    • 909.Snakes-and-Ladders
    • 93.Restore-IP-Addresses
    • 95.Unique-Binary-Search-Trees-II
    • 96.Unique-Binary-Search-Trees
    • 994.Rotting-Oranges
  • Linked List
    • Add Two Numbers
      • 2.Add-Two-Numbers
      • 445.Add-Two-Numbers-II
    • 109.Convert-Sorted-List-to-Binary-Search-Tree
    • 138.Copy-List-with-Random-Pointer
    • 141.Linked-List-Cycle
    • 142.Linked-List-Cycle-II
    • 143.Reorder-List
    • 148.Sort-List
    • 160.Intersection-of-Two-Linked-Lists
    • 19.Remove-Nth-Node-From-End-of-List
    • 206.Reverse-Linked-List
    • 21.Merge-Two-Sorted-Lists
    • 23.Merge-k-Sorted-Lists
    • 234.Palindrome-Linked-List
    • 237.Delete-Node-in-a-Linked-List
    • 24.Swap-Nodes-in-Pairs
    • 25.Reverse-Nodes-in-k-Group
    • 328.Odd-Even-Linked-List
    • 369.Plus-One-Linked-List
    • 61.Rotate-List
    • 82.Remove-Duplicates-from-Sorted-List-II
    • 83.Remove-Duplicates-from-Sorted-List
    • 86.Partition-List
    • 876.Middle-of-the-Linked-List
    • 92.Reverse-Linked-List-II
    • Remove Duplicates From Unsorted List Geeksforgeeks
  • Matrix
    • Spiral Matrix
      • 54.Spiral-Matrix
      • 59.Spiral-Matrix-II
    • 1074.Number-of-Submatrices-That-Sum-to-Target
    • 1292.Maximum-Side-Length-of-a-Square-with-Sum-Less-than-or-Equal-to-Threshold
    • 240.Search-a-2D-Matrix-II
    • 296.Best-Meeting-Point
    • 304.Range-Sum-Query-2D---Immutable
    • 311.Sparse-Matrix-Multiplication
    • 36.Valid-Sudoku
    • 363.Max-Sum-of-Rectangle-No-Larger-Than-K
    • 37.Sudoku-Solver
    • 48.Rotate-Image
    • 498.Diagonal-Traverse
    • 562.Longest-Line-of-Consecutive-One-in-Matrix
    • 723.Candy-Crush
    • 73.Set-Matrix-Zeroes
    • 835.Image-Overlap
    • 939.Minimum-Area-Rectangle
    • 963.Minimum-Area-Rectangle-II
    • 986.Interval-List-Intersections
    • Friend Circles
  • Mergesort
    • Algorithm Swap
  • Numbers
    • 1088.Confusing-Number-II
    • 13.Roman-to-Integer
    • 166.Fraction-to-Recurring-Decimal
    • 202.Happy-Number
    • 65.Valid-Number
    • 681.Next-Closest-Time
    • 780.Reaching-Points
    • 829.Consecutive-Numbers-Sum
    • 914.X-of-a-Kind-in-a-Deck-of-Cards
    • 991.Broken-Calculator
  • Other
    • 1185.Day-of-the-Week
    • 149.Max-Points-on-a-Line
    • 176.Second-Highest-Salary
    • 20.Valid-Parentheses
    • 277.Find-the-Celebrity
    • 612.Shortest-Distance-in-a-Plane
    • [8.String-to-Integer-(atoi)](Other/8.String-to-Integer-(atoi).md)
  • Permutation And Combination
    • 46.Permutations
    • 47.Permutations-II
    • 60.Permutation-Sequence
    • 77.Combinations
    • 78.Subsets
    • 90.Subsets-II
  • Queue
    • 480.Sliding-Window-Median
    • 853.Car-Fleet
    • 862.Shortest-Subarray-with-Sum-at-Least-K
    • 950.Reveal-Cards-In-Increasing-Order
  • Sort Algorithm
    • 1057.Campus-Bikes
    • 969.Pancake-Sorting
    • Bubble Sort
    • Merge Sort
    • Quick Sort
  • Stack
    • 1130.Minimum-Cost-Tree-From-Leaf-Values
    • 1249.Minimum-Remove-to-Make-Valid-Parentheses
    • 379.Design-Phone-Directory
    • 394.Decode-String
    • 402.Remove-K-Digits
    • 456.132-Pattern
    • 496.Next-Greater-Element-I
    • 503.Next-Greater-Element-II
    • 636.Exclusive-Time-of-Functions
    • 71.Simplify-Path
    • 739.Daily-Temperatures
    • 844.Backspace-String-Compare
    • 917.Reverse-Only-Letters
    • 946.Validate-Stack-Sequences
  • String
    • 1055.Shortest-Way-to-Form-String
    • 1096.Brace-Expansion-II
    • 1100.Find-K-Length-Substrings-With-No-Repeated-Characters
    • 1153.String-Transforms-Into-Another-String
    • 12.Integer-to-Roman
    • 125.Valid-Palindrome
    • 151.Reverse-Words-in-a-String
    • 161.One-Edit-Distance
    • 165.Compare-Version-Numbers
    • 168.Excel-Sheet-Column-Title
    • 171.Excel-Sheet-Column-Number
    • 205.Isomorphic-Strings
    • 214.Shortest-Palindrome
    • 242.Valid-Anagram
    • 3.Longest-Substring-Without-Repeating-Characters
    • 344.Reverse-String
    • 415.Add-Strings
    • 43.Multiply-Strings
    • 443.String-Compression
    • 459.Repeated-Substring-Pattern
    • 482.License-Key-Formatting
    • 5.Longest-Palindromic-Substring
    • 556.Next-Greater-Element-III
    • 557.Reverse-Words-in-a-String-III
    • 567.Permutation-in-String
    • 640.Solve-the-Equation
    • 68.Text-Justification
    • 726.Number-of-Atoms
    • 736.Parse-Lisp-Expression
    • 767.Reorganize-String
    • 784.Letter-Case-Permutation
    • 792.Number-of-Matching-Subsequences
    • 809.Expressive-Words
    • 819.Most-Common-Word
    • 833.Find-And-Replace-in-String
  • Toposort
    • 1136.Parallel-Courses
    • 207.Course-Schedule
    • 210.Course-Schedule-II
    • 269.Alien-Dictionary
    • 444.Sequence-Reconstruction
    • 468.Validate-IP-Address
    • Topological Sorting
  • Trie Tree
    • 1032.Stream-of-Characters
    • 1268.Search-Suggestions-System
    • [208.Implement-Trie-(Prefix-Tree)](Trie-Tree/208.Implement-Trie-(Prefix-Tree).md)
    • 336.Palindrome-Pairs
  • Two Pointers
    • 1004.Max-Consecutive-Ones-III
    • 1099.Two-Sum-Less-Than-K
    • 159.Longest-Substring-with-At-Most-Two-Distinct-Characters
    • 167.Two-Sum-II---Input-array-is-sorted
    • 26.Remove-Duplicates-from-Sorted-Array
    • 27.Remove-Element
    • 340.Longest-Substring-with-At-Most-K-Distinct-Characters
    • 42.Trapping-Rain-Water
    • 647.Palindromic-Substrings
    • 680.Valid-Palindrome-II
    • 75.Sort-Colors
    • 76.Minimum-Window-Substring
    • 88.Merge-Sorted-Array
    • Sort Colors Ii
  • Union Find
    • 1168.Optimize-Water-Distribution-in-a-Village
    • 803.Bricks-Falling-When-Hit
    • 924.Minimize-Malware-Spread
    • 947.Most-Stones-Removed-with-Same-Row-or-Column
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  • 609. Find Duplicate File in System
  • 题目地址
  • 题目描述
  • 代码
  • Approach #1 HashMap

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  1. Array

609.Find-Duplicate-File-in-System

Previous6.ZigZag-ConversionNext611.Valid-Triangle-Number

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609. Find Duplicate File in System

题目地址

题目描述

Given a list of directory info including directory path, and all the files with contents in this directory, you need to find out all the groups of duplicate files in the file system in terms of their paths.

A group of duplicate files consists of at least two files that have exactly the same content.

A single directory info string in the input list has the following format:

"root/d1/d2/.../dm f1.txt(f1_content) f2.txt(f2_content) ... fn.txt(fn_content)"

It means there are n files (f1.txt, f2.txt ... fn.txt with content f1_content, f2_content ... fn_content, respectively) in directory root/d1/d2/.../dm. Note that n >= 1 and m >= 0. If m = 0, it means the directory is just the root directory.

The output is a list of group of duplicate file paths. For each group, it contains all the file paths of the files that have the same content. A file path is a string that has the following format:

"directory_path/file_name.txt"

Example 1:
Input:
["root/a 1.txt(abcd) 2.txt(efgh)", "root/c 3.txt(abcd)", "root/c/d 4.txt(efgh)", "root 4.txt(efgh)"]
Output:  
[["root/a/2.txt","root/c/d/4.txt","root/4.txt"],["root/a/1.txt","root/c/3.txt"]]


Note:
No order is required for the final output.
You may assume the directory name, file name and file content only has letters and digits, and the length of file content is in the range of [1,50].
The number of files given is in the range of [1,20000].
You may assume no files or directories share the same name in the same directory.
You may assume each given directory info represents a unique directory. Directory path and file info are separated by a single blank space.

Follow-up beyond contest:
Imagine you are given a real file system, how will you search files? DFS or BFS?
If the file content is very large (GB level), how will you modify your solution?
If you can only read the file by 1kb each time, how will you modify your solution?
What is the time complexity of your modified solution? What is the most time-consuming part and memory consuming part of it? How to optimize?
How to make sure the duplicated files you find are not false positive?

代码

Approach #1 HashMap

class Solution {
  public List<List<String>> findDuplicate(String[] paths) {
        HashMap<String, List<String>> map = new HashMap();
    for (String path: paths) {
      String[] values = path.split(" ");
      for (int i = 1; i < values.length; i++) {
        String[] name_cont = vlaues[i].split("\\(");
        name_cont[1] = name_cont[1].replace(")", "");
        List<String> list = map.getOrDefault(name_cont[1], new ArrayList<String>());
        list.add(values[0] + "/" + name_cont[0]);
        map.put(name_cont[1], list);
      }
    }

    List<List<String>> res = new ArrayList();
    for (String key: map.keySet()) {
      if (map.get(key).size() > 1) {
        res.add(map.get(key));
      }
    }

    return res;
  }
}
https://leetcode.com/problems/find-duplicate-file-in-system/