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
551. Student Attendance Record I	Easy	50.1%	String	Read
552. Student Attendance Record II	Hard	56.5%	Dynamic Programming	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
557. Reverse Words in a String III	Easy	84.0%	String Two Pointers	Read
558. Logical OR of Two Binary Grids Represented as Quad-Trees	Medium	53.3%	Divide and Conquer Tree	Read
559. Maximum Depth of N-ary Tree	Easy	73.5%	Breadth-First Search Depth-First Search+1	Read
560. Subarray Sum Equals K	Medium	48.2%	Array Hash Table+1	Read
561. Array Partition	Easy	82.2%	Array Counting Sort+2	Read
562. Longest Line of Consecutive One in Matrix	Medium	50.5%	Array Dynamic Programming+1	Read
563. Binary Tree Tilt	Easy	66.2%	Binary Tree Depth-First Search+1	Read
564. Find the Closest Palindrome	Hard	31.6%	Math String	Read
565. Array Nesting	Medium	56.6%	Array Depth-First Search	Read
566. Reshape the Matrix	Easy	65.4%	Array Matrix+1	Read
567. Permutation in String	Medium	49.8%	Hash Table Sliding Window+2	Read
568. Maximum Vacation Days	Hard	46.7%	Array Dynamic Programming+1	Read
569. Median Employee Salary	Hard	65.9%	Database	Read
570. Managers with at Least 5 Direct Reports	Medium	49.4%	Database	Read
571. Find Median Given Frequency of Numbers	Hard	42.4%	Database	Read
572. Subtree of Another Tree	Easy	52.0%	Binary Tree Depth-First Search+3	Read
573. Squirrel Simulation	Medium	57.1%	Array Math	Read
574. Winning Candidate	Medium	61.3%	Database	Read
575. Distribute Candies	Easy	71.5%	Array Hash Table	Read
576. Out of Boundary Paths	Medium	48.1%	Dynamic Programming	Read
577. Employee Bonus	Easy	76.7%	Database	Read
578. Get Highest Answer Rate Question	Medium	40.2%	Database	Read
579. Find Cumulative Salary of an Employee	Hard	47.8%	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
584. Find Customer Referee	Easy	71.2%	Database	Read
585. Investments in 2016	Medium	49.4%	Database	Read
586. Customer Placing the Largest Number of Orders	Easy	64.6%	Database	Read
587. Erect the Fence	Hard	53.4%	Array Geometry+1	Read
588. Design In-Memory File System	Hard	48.0%	Design Hash Table+3	Read
589. N-ary Tree Preorder Traversal	Easy	76.7%	Depth-First Search Stack+1	Read
590. N-ary Tree Postorder Traversal	Easy	81.0%	Depth-First Search Stack+1	Read
591. Tag Validator	Hard	41.7%	Stack String	Read
592. Fraction Addition and Subtraction	Medium	66.6%	Math Simulation+1	Read
593. Valid Square	Medium	45.5%	Geometry Math	Read
594. Longest Harmonious Subsequence	Easy	65.1%	Array Counting+3	Read
595. Big Countries	Easy	68.2%	Database	Read
596. Classes More Than 5 Students	Easy	58.4%	Database	Read
597. Friend Requests I: Overall Acceptance Rate	Easy	41.6%	Database	Read
598. Range Addition II	Easy	59.1%	Array Math	Read
599. Minimum Index Sum of Two Lists	Easy	60.2%	Array Hash Table+1	Read
600. Non-negative Integers without Consecutive Ones	Hard	43.1%	Dynamic Programming	Read

#551Easy

Student Attendance Record I

String

Acceptance: 50.1%

#552Hard

Student Attendance Record II

Dynamic Programming

Acceptance: 56.5%

#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%

#557Easy

Reverse Words in a String III

StringTwo Pointers

Acceptance: 84.0%

#558Medium

Logical OR of Two Binary Grids Represented as Quad-Trees

Divide and ConquerTree

Acceptance: 53.3%

#559Easy

Maximum Depth of N-ary Tree

Breadth-First SearchDepth-First SearchTree

Acceptance: 73.5%

#560Medium

Subarray Sum Equals K

ArrayHash TablePrefix Sum

Acceptance: 48.2%

#561Easy

Array Partition

ArrayCounting SortGreedy+1

Acceptance: 82.2%

#562Medium

Longest Line of Consecutive One in Matrix

ArrayDynamic ProgrammingMatrix

Acceptance: 50.5%

#563Easy

Binary Tree Tilt

Binary TreeDepth-First SearchTree

Acceptance: 66.2%

#564Hard

Find the Closest Palindrome

MathString

Acceptance: 31.6%

#565Medium

Array Nesting

ArrayDepth-First Search

Acceptance: 56.6%

#566Easy

Reshape the Matrix

ArrayMatrixSimulation

Acceptance: 65.4%

#567Medium

Permutation in String

Hash TableSliding WindowString+1

Acceptance: 49.8%

#568Hard

Maximum Vacation Days

ArrayDynamic ProgrammingMatrix

Acceptance: 46.7%

#569Hard

Median Employee Salary

Database

Acceptance: 65.9%

#570Medium

Managers with at Least 5 Direct Reports

Database

Acceptance: 49.4%

#571Hard

Find Median Given Frequency of Numbers

Database

Acceptance: 42.4%

#572Easy

Subtree of Another Tree

Binary TreeDepth-First SearchHash Function+2

Acceptance: 52.0%

#573Medium

Squirrel Simulation

ArrayMath

Acceptance: 57.1%

#574Medium

Winning Candidate

Database

Acceptance: 61.3%

#575Easy

Distribute Candies

ArrayHash Table

Acceptance: 71.5%

#576Medium

Out of Boundary Paths

Dynamic Programming

Acceptance: 48.1%

#577Easy

Employee Bonus

Database

Acceptance: 76.7%

#578Medium

Get Highest Answer Rate Question

Database

Acceptance: 40.2%

#579Hard

Find Cumulative Salary of an Employee

Database

Acceptance: 47.8%

#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%

#584Easy

Find Customer Referee

Database

Acceptance: 71.2%

#585Medium

Investments in 2016

Database

Acceptance: 49.4%

#586Easy

Customer Placing the Largest Number of Orders

Database

Acceptance: 64.6%

#587Hard

Erect the Fence

ArrayGeometryMath

Acceptance: 53.4%

#588Hard

Design In-Memory File System

DesignHash TableSorting+2

Acceptance: 48.0%

#589Easy

N-ary Tree Preorder Traversal

Depth-First SearchStackTree

Acceptance: 76.7%

#590Easy

N-ary Tree Postorder Traversal

Depth-First SearchStackTree

Acceptance: 81.0%

#591Hard

Tag Validator

StackString

Acceptance: 41.7%

#592Medium

Fraction Addition and Subtraction

MathSimulationString

Acceptance: 66.6%

#593Medium

Valid Square

GeometryMath

Acceptance: 45.5%

#594Easy

Longest Harmonious Subsequence

ArrayCountingHash Table+2

Acceptance: 65.1%

#595Easy

Big Countries

Database

Acceptance: 68.2%

#596Easy

Classes More Than 5 Students

Database

Acceptance: 58.4%

#597Easy

Friend Requests I: Overall Acceptance Rate

Database

Acceptance: 41.6%

#598Easy

Range Addition II

ArrayMath

Acceptance: 59.1%

#599Easy

Minimum Index Sum of Two Lists

ArrayHash TableString

Acceptance: 60.2%

#600Hard

Non-negative Integers without Consecutive Ones

Dynamic Programming

Acceptance: 43.1%

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Master DSA with Step-by-Step Solutions

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