Solutions & Explanations

Browse 4,029+ detailed solutions with multiple approaches, code in Python, Java, C++ and more.

4,029 Solutions961 Easy2102 Medium966 Hard

Title	Difficulty	Acceptance	Topics	Solution
522. Longest Uncommon Subsequence II	Medium	45.2%	Array Hash Table+3	Read
523. Continuous Subarray Sum	Medium	31.3%	Array Hash Table+2	Read
524. Longest Word in Dictionary through Deleting	Medium	52.6%	Array Sorting+2	Read
525. Contiguous Array	Medium	52.2%	Array Hash Table+1	Read
526. Beautiful Arrangement	Medium	64.9%	Array Backtracking+3	Read
528. Random Pick with Weight	Medium	49.0%	Array Binary Search+3	Read
529. Minesweeper	Medium	68.7%	Array Breadth-First Search+2	Read
531. Lonely Pixel I	Medium	62.3%	Array Hash Table+1	Read
532. K-diff Pairs in an Array	Medium	46.3%	Array Binary Search+3	Read
533. Lonely Pixel II	Medium	48.7%	Array Hash Table+1	Read
534. Game Play Analysis III	Medium	81.0%	Database	Read
535. Encode and Decode TinyURL	Medium	86.5%	Design Hash Function+2	Read
536. Construct Binary Tree from String	Medium	58.7%	Binary Tree Depth-First Search+3	Read
537. Complex Number Multiplication	Medium	73.3%	Math Simulation+1	Read
538. Convert BST to Greater Tree	Medium	71.5%	Binary Search Tree Binary Tree+2	Read
539. Minimum Time Difference	Medium	62.7%	Array Math+2	Read
540. Single Element in a Sorted Array	Medium	59.3%	Array Binary Search	Read
542. 01 Matrix	Medium	54.7%	Array Breadth-First Search+2	Read
544. Output Contest Matches	Medium	77.3%	Recursion Simulation+1	Read
545. Boundary of Binary Tree	Medium	48.0%	Binary Tree Depth-First Search+1	Read
547. Number of Provinces	Medium	70.8%	Breadth-First Search Depth-First Search+2	Read
549. Binary Tree Longest Consecutive Sequence II	Medium	50.1%	Binary Tree Depth-First Search+1	Read
550. Game Play Analysis IV	Medium	38.4%	Database	Read
553. Optimal Division	Medium	63.4%	Array Dynamic Programming+1	Read
554. Brick Wall	Medium	56.1%	Array Hash Table	Read
555. Split Concatenated Strings	Medium	43.4%	Array Greedy+1	Read
556. Next Greater Element III	Medium	35.2%	Math String+1	Read
558. Logical OR of Two Binary Grids Represented as Quad-Trees	Medium	53.3%	Divide and Conquer Tree	Read
560. Subarray Sum Equals K	Medium	48.2%	Array Hash Table+1	Read
562. Longest Line of Consecutive One in Matrix	Medium	50.5%	Array Dynamic Programming+1	Read
565. Array Nesting	Medium	56.6%	Array Depth-First Search	Read
567. Permutation in String	Medium	49.8%	Hash Table Sliding Window+2	Read
570. Managers with at Least 5 Direct Reports	Medium	49.4%	Database	Read
573. Squirrel Simulation	Medium	57.1%	Array Math	Read
574. Winning Candidate	Medium	61.3%	Database	Read
576. Out of Boundary Paths	Medium	48.1%	Dynamic Programming	Read
578. Get Highest Answer Rate Question	Medium	40.2%	Database	Read
580. Count Student Number in Departments	Medium	59.4%	Database	Read
581. Shortest Unsorted Continuous Subarray	Medium	38.1%	Array Greedy+4	Read
582. Kill Process	Medium	70.4%	Array Breadth-First Search+3	Read
583. Delete Operation for Two Strings	Medium	66.0%	Dynamic Programming String	Read
585. Investments in 2016	Medium	49.4%	Database	Read
592. Fraction Addition and Subtraction	Medium	66.6%	Math Simulation+1	Read
593. Valid Square	Medium	45.5%	Geometry Math	Read
602. Friend Requests II: Who Has the Most Friends	Medium	59.2%	Database	Read
606. Construct String from Binary Tree	Medium	70.6%	Binary Tree Depth-First Search+2	Read
608. Tree Node	Medium	73.1%	Database	Read
609. Find Duplicate File in System	Medium	67.6%	Array Hash Table+1	Read
611. Valid Triangle Number	Medium	56.8%	Array Binary Search+3	Read
612. Shortest Distance in a Plane	Medium	61.3%	Database	Read

#522Medium

Longest Uncommon Subsequence II

ArrayHash TableSorting+2

Acceptance: 45.2%

#523Medium

Continuous Subarray Sum

ArrayHash TableMath+1

Acceptance: 31.3%

#524Medium

Longest Word in Dictionary through Deleting

ArraySortingString+1

Acceptance: 52.6%

#525Medium

Contiguous Array

ArrayHash TablePrefix Sum

Acceptance: 52.2%

#526Medium

Beautiful Arrangement

ArrayBacktrackingBit Manipulation+2

Acceptance: 64.9%

#528Medium

Random Pick with Weight

ArrayBinary SearchMath+2

Acceptance: 49.0%

#529Medium

Minesweeper

ArrayBreadth-First SearchDepth-First Search+1

Acceptance: 68.7%

#531Medium

Lonely Pixel I

ArrayHash TableMatrix

Acceptance: 62.3%

#532Medium

K-diff Pairs in an Array

ArrayBinary SearchHash Table+2

Acceptance: 46.3%

#533Medium

Lonely Pixel II

ArrayHash TableMatrix

Acceptance: 48.7%

#534Medium

Game Play Analysis III

Database

Acceptance: 81.0%

#535Medium

Encode and Decode TinyURL

DesignHash FunctionHash Table+1

Acceptance: 86.5%

#536Medium

Construct Binary Tree from String

Binary TreeDepth-First SearchStack+2

Acceptance: 58.7%

#537Medium

Complex Number Multiplication

MathSimulationString

Acceptance: 73.3%

#538Medium

Convert BST to Greater Tree

Binary Search TreeBinary TreeDepth-First Search+1

Acceptance: 71.5%

#539Medium

Minimum Time Difference

ArrayMathSorting+1

Acceptance: 62.7%

#540Medium

Single Element in a Sorted Array

ArrayBinary Search

Acceptance: 59.3%

#542Medium

01 Matrix

ArrayBreadth-First SearchDynamic Programming+1

Acceptance: 54.7%

#544Medium

Output Contest Matches

RecursionSimulationString

Acceptance: 77.3%

#545Medium

Boundary of Binary Tree

Binary TreeDepth-First SearchTree

Acceptance: 48.0%

#547Medium

Number of Provinces

Breadth-First SearchDepth-First SearchGraph+1

Acceptance: 70.8%

#549Medium

Binary Tree Longest Consecutive Sequence II

Binary TreeDepth-First SearchTree

Acceptance: 50.1%

#550Medium

Game Play Analysis IV

Database

Acceptance: 38.4%

#553Medium

Optimal Division

ArrayDynamic ProgrammingMath

Acceptance: 63.4%

#554Medium

Brick Wall

ArrayHash Table

Acceptance: 56.1%

#555Medium

Split Concatenated Strings

ArrayGreedyString

Acceptance: 43.4%

#556Medium

Next Greater Element III

MathStringTwo Pointers

Acceptance: 35.2%

#558Medium

Logical OR of Two Binary Grids Represented as Quad-Trees

Divide and ConquerTree

Acceptance: 53.3%

#560Medium

Subarray Sum Equals K

ArrayHash TablePrefix Sum

Acceptance: 48.2%

#562Medium

Longest Line of Consecutive One in Matrix

ArrayDynamic ProgrammingMatrix

Acceptance: 50.5%

#565Medium

Array Nesting

ArrayDepth-First Search

Acceptance: 56.6%

#567Medium

Permutation in String

Hash TableSliding WindowString+1

Acceptance: 49.8%

#570Medium

Managers with at Least 5 Direct Reports

Database

Acceptance: 49.4%

#573Medium

Squirrel Simulation

ArrayMath

Acceptance: 57.1%

#574Medium

Winning Candidate

Database

Acceptance: 61.3%

#576Medium

Out of Boundary Paths

Dynamic Programming

Acceptance: 48.1%

#578Medium

Get Highest Answer Rate Question

Database

Acceptance: 40.2%

#580Medium

Count Student Number in Departments

Database

Acceptance: 59.4%

#581Medium

Shortest Unsorted Continuous Subarray

ArrayGreedyMonotonic Stack+3

Acceptance: 38.1%

#582Medium

Kill Process

ArrayBreadth-First SearchDepth-First Search+2

Acceptance: 70.4%

#583Medium

Delete Operation for Two Strings

Dynamic ProgrammingString

Acceptance: 66.0%

#585Medium

Investments in 2016

Database

Acceptance: 49.4%

#592Medium

Fraction Addition and Subtraction

MathSimulationString

Acceptance: 66.6%

#593Medium

Valid Square

GeometryMath

Acceptance: 45.5%

#602Medium

Friend Requests II: Who Has the Most Friends

Database

Acceptance: 59.2%

#606Medium

Construct String from Binary Tree

Binary TreeDepth-First SearchString+1

Acceptance: 70.6%

#608Medium

Tree Node

Database

Acceptance: 73.1%

#609Medium

Find Duplicate File in System

ArrayHash TableString

Acceptance: 67.6%

#611Medium

Valid Triangle Number

ArrayBinary SearchGreedy+2

Acceptance: 56.8%

#612Medium

Shortest Distance in a Plane

Database

Acceptance: 61.3%

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