📖
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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  • 1145. Binary Tree Coloring Game
  • 题目地址
  • 题目描述
  • 代码
  • Approach 1:

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  1. Binary Tree

1145.Binary-Tree-Coloring-Game

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1145. Binary Tree Coloring Game

题目地址

题目描述

Two players play a turn based game on a binary tree.  We are given the root of this binary tree, and the number of nodes n in the tree.  n is odd, and each node has a distinct value from 1 to n.

Initially, the first player names a value x with 1 <= x <= n, and the second player names a value y with 1 <= y <= n and y != x.  The first player colors the node with value x red, and the second player colors the node with value y blue.

Then, the players take turns starting with the first player.  In each turn, that player chooses a node of their color (red if player 1, blue if player 2) and colors an uncolored neighbor of the chosen node (either the left child, right child, or parent of the chosen node.)

If (and only if) a player cannot choose such a node in this way, they must pass their turn.  If both players pass their turn, the game ends, and the winner is the player that colored more nodes.

You are the second player.  If it is possible to choose such a y to ensure you win the game, return true.  If it is not possible, return false.

Example 1:
Input: root = [1,2,3,4,5,6,7,8,9,10,11], n = 11, x = 3
Output: true
Explanation: The second player can choose the node with value 2.

Constraints:
root is the root of a binary tree with n nodes and distinct node values from 1 to n.
n is odd.
1 <= x <= n <= 100

代码

Approach 1:

Time O(N) Space O(height) for recursion

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {
  int left, right, val;
  public boolean btreeGameWinningMove(TreeNode root, int n, int x) {
        val = x;
    count(root);
    return Math.max(Math.max(left, right), n - left - right - 1) > n / 2;
  }

  private int count(TreeNode node) {
    if (node == null)    return 0;
    int l = count(node.left);
    int r = count(node.right);
    if (node.val == val) {
      left = l;
      right = r;
    }
    return l + r + 1;
  }
}
https://leetcode.com/problems/binary-tree-coloring-game/