📖
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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  • 176. Second Highest Salary
  • 题目地址
  • 题目描述
  • 代码
  • Approach #1 Using sub-query and LIMIT clause
  • Approach #2 Using IFNULL and LIMIT clause

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176.Second-Highest-Salary

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176. Second Highest Salary

题目地址

题目描述

SQL Schema
Write a SQL query to get the second highest salary from the Employee table.

+----+--------+
| Id | Salary |
+----+--------+
| 1  | 100    |
| 2  | 200    |
| 3  | 300    |
+----+--------+
For example, given the above Employee table, the query should return 200 as the second highest salary. If there is no second highest salary, then the query should return null.

+---------------------+
| SecondHighestSalary |
+---------------------+
| 200                 |
+---------------------+

代码

Approach #1 Using sub-query and LIMIT clause

However, this solution will be judged as 'Wrong Answer' if there is no such second highest salary since there might be only one record in this table. To overcome this issue, we can take this as a temp table.

# Write your MySQL query statement below
SELECT DISTINCT
    Salary AS SecondHighestSalary
FROM
    Employee
ORDER BY Salary DESC
LIMIT 1 OFFSET 1


## To overcome this issue, we can take this as a temp table.
SELECT
    (SELECT DISTINCT
            Salary
        FROM
            Employee
        ORDER BY Salary DESC
        LIMIT 1 OFFSET 1) AS SecondHighestSalary
;

Approach #2 Using IFNULL and LIMIT clause

Another way to solve the 'NULL' problem is to use IFNULL funtion as below.

SELECT
    IFNULL(
      (SELECT DISTINCT Salary 
    FROM Employee
    ORDER BY Salary DESC
    LIMIT 1 OFFSET 1),
    NULL) AS SecondHightestSalary
https://leetcode.com/problems/second-highest-salary/