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
832. Flipping an Image	Easy	83.6%	Array Bit Manipulation+3	Read
836. Rectangle Overlap	Easy	53.0%	Geometry Math	Read
844. Backspace String Compare	Easy	49.9%	Simulation Stack+2	Read
859. Buddy Strings	Easy	34.0%	Hash Table String	Read
860. Lemonade Change	Easy	59.0%	Array Greedy	Read
867. Transpose Matrix	Easy	76.8%	Array Matrix+1	Read
868. Binary Gap	Easy	74.2%	Bit Manipulation	Read
872. Leaf-Similar Trees	Easy	70.0%	Binary Tree Depth-First Search+1	Read
876. Middle of the Linked List	Easy	82.3%	Linked List Two Pointers	Read
883. Projection Area of 3D Shapes	Easy	76.3%	Array Geometry+2	Read
884. Uncommon Words from Two Sentences	Easy	75.8%	Counting Hash Table+1	Read
888. Fair Candy Swap	Easy	65.3%	Array Binary Search+2	Read
892. Surface Area of 3D Shapes	Easy	71.2%	Array Geometry+2	Read
896. Monotonic Array	Easy	62.3%	Array	Read
897. Increasing Order Search Tree	Easy	79.1%	Binary Search Tree Binary Tree+3	Read
905. Sort Array By Parity	Easy	76.2%	Array Sorting+1	Read
908. Smallest Range I	Easy	74.0%	Array Math	Read
914. X of a Kind in a Deck of Cards	Easy	30.4%	Array Counting+3	Read
917. Reverse Only Letters	Easy	68.9%	String Two Pointers	Read
922. Sort Array By Parity II	Easy	71.4%	Array Sorting+1	Read
925. Long Pressed Name	Easy	32.8%	String Two Pointers	Read
929. Unique Email Addresses	Easy	67.9%	Array Hash Table+1	Read
933. Number of Recent Calls	Easy	78.9%	Data Stream Design+1	Read
938. Range Sum of BST	Easy	87.2%	Binary Search Tree Binary Tree+2	Read
941. Valid Mountain Array	Easy	35.7%	Array	Read
942. DI String Match	Easy	81.0%	Array Greedy+2	Read
944. Delete Columns to Make Sorted	Easy	78.1%	Array String	Read
953. Verifying an Alien Dictionary	Easy	55.9%	Array Hash Table+1	Read
961. N-Repeated Element in Size 2N Array	Easy	79.9%	Array Hash Table	Read
965. Univalued Binary Tree	Easy	72.9%	Binary Tree Breadth-First Search+2	Read
976. Largest Perimeter Triangle	Easy	62.1%	Array Greedy+2	Read
977. Squares of a Sorted Array	Easy	73.7%	Array Sorting+1	Read
989. Add to Array-Form of Integer	Easy	45.6%	Array Math	Read
993. Cousins in Binary Tree	Easy	59.8%	Binary Tree Breadth-First Search+2	Read
997. Find the Town Judge	Easy	50.6%	Array Graph+1	Read
999. Available Captures for Rook	Easy	72.2%	Array Matrix+1	Read
1002. Find Common Characters	Easy	74.6%	Array Hash Table+1	Read
1005. Maximize Sum Of Array After K Negations	Easy	54.3%	Array Greedy+1	Read
1009. Complement of Base 10 Integer	Easy	63.3%	Bit Manipulation	Read
1013. Partition Array Into Three Parts With Equal Sum	Easy	42.6%	Array Greedy	Read
1018. Binary Prefix Divisible By 5	Easy	53.5%	Array Bit Manipulation	Read
1021. Remove Outermost Parentheses	Easy	87.5%	Stack String	Read
1022. Sum of Root To Leaf Binary Numbers	Easy	76.6%	Binary Tree Depth-First Search+1	Read
1025. Divisor Game	Easy	72.3%	Brainteaser Dynamic Programming+2	Read
1030. Matrix Cells in Distance Order	Easy	74.6%	Array Geometry+3	Read
1037. Valid Boomerang	Easy	39.9%	Array Geometry+1	Read
1046. Last Stone Weight	Easy	66.4%	Array Heap (Priority Queue)	Read
1047. Remove All Adjacent Duplicates In String	Easy	73.6%	Stack String	Read
1050. Actors and Directors Who Cooperated At Least Three Times	Easy	70.3%	Database	Read
1051. Height Checker	Easy	81.6%	Array Counting Sort+1	Read

#832Easy

Flipping an Image

ArrayBit ManipulationMatrix+2

Acceptance: 83.6%

#836Easy

Rectangle Overlap

GeometryMath

Acceptance: 53.0%

#844Easy

Backspace String Compare

SimulationStackString+1

Acceptance: 49.9%

#859Easy

Buddy Strings

Hash TableString

Acceptance: 34.0%

#860Easy

Lemonade Change

ArrayGreedy

Acceptance: 59.0%

#867Easy

Transpose Matrix

ArrayMatrixSimulation

Acceptance: 76.8%

#868Easy

Binary Gap

Bit Manipulation

Acceptance: 74.2%

#872Easy

Leaf-Similar Trees

Binary TreeDepth-First SearchTree

Acceptance: 70.0%

#876Easy

Middle of the Linked List

Linked ListTwo Pointers

Acceptance: 82.3%

#883Easy

Projection Area of 3D Shapes

ArrayGeometryMath+1

Acceptance: 76.3%

#884Easy

Uncommon Words from Two Sentences

CountingHash TableString

Acceptance: 75.8%

#888Easy

Fair Candy Swap

ArrayBinary SearchHash Table+1

Acceptance: 65.3%

#892Easy

Surface Area of 3D Shapes

ArrayGeometryMath+1

Acceptance: 71.2%

#896Easy

Monotonic Array

Array

Acceptance: 62.3%

#897Easy

Increasing Order Search Tree

Binary Search TreeBinary TreeDepth-First Search+2

Acceptance: 79.1%

#905Easy

Sort Array By Parity

ArraySortingTwo Pointers

Acceptance: 76.2%

#908Easy

Smallest Range I

ArrayMath

Acceptance: 74.0%

#914Easy

X of a Kind in a Deck of Cards

ArrayCountingHash Table+2

Acceptance: 30.4%

#917Easy

Reverse Only Letters

StringTwo Pointers

Acceptance: 68.9%

#922Easy

Sort Array By Parity II

ArraySortingTwo Pointers

Acceptance: 71.4%

#925Easy

Long Pressed Name

StringTwo Pointers

Acceptance: 32.8%

#929Easy

Unique Email Addresses

ArrayHash TableString

Acceptance: 67.9%

#933Easy

Number of Recent Calls

Data StreamDesignQueue

Acceptance: 78.9%

#938Easy

Range Sum of BST

Binary Search TreeBinary TreeDepth-First Search+1

Acceptance: 87.2%

#941Easy

Valid Mountain Array

Array

Acceptance: 35.7%

#942Easy

DI String Match

ArrayGreedyString+1

Acceptance: 81.0%

#944Easy

Delete Columns to Make Sorted

ArrayString

Acceptance: 78.1%

#953Easy

Verifying an Alien Dictionary

ArrayHash TableString

Acceptance: 55.9%

#961Easy

N-Repeated Element in Size 2N Array

ArrayHash Table

Acceptance: 79.9%

#965Easy

Univalued Binary Tree

Binary TreeBreadth-First SearchDepth-First Search+1

Acceptance: 72.9%

#976Easy

Largest Perimeter Triangle

ArrayGreedyMath+1

Acceptance: 62.1%

#977Easy

Squares of a Sorted Array

ArraySortingTwo Pointers

Acceptance: 73.7%

#989Easy

Add to Array-Form of Integer

ArrayMath

Acceptance: 45.6%

#993Easy

Cousins in Binary Tree

Binary TreeBreadth-First SearchDepth-First Search+1

Acceptance: 59.8%

#997Easy

Find the Town Judge

ArrayGraphHash Table

Acceptance: 50.6%

#999Easy

Available Captures for Rook

ArrayMatrixSimulation

Acceptance: 72.2%

#1002Easy

Find Common Characters

ArrayHash TableString

Acceptance: 74.6%

#1005Easy

Maximize Sum Of Array After K Negations

ArrayGreedySorting

Acceptance: 54.3%

#1009Easy

Complement of Base 10 Integer

Bit Manipulation

Acceptance: 63.3%

#1013Easy

Partition Array Into Three Parts With Equal Sum

ArrayGreedy

Acceptance: 42.6%

#1018Easy

Binary Prefix Divisible By 5

ArrayBit Manipulation

Acceptance: 53.5%

#1021Easy

Remove Outermost Parentheses

StackString

Acceptance: 87.5%

#1022Easy

Sum of Root To Leaf Binary Numbers

Binary TreeDepth-First SearchTree

Acceptance: 76.6%

#1025Easy

Divisor Game

BrainteaserDynamic ProgrammingGame Theory+1

Acceptance: 72.3%

#1030Easy

Matrix Cells in Distance Order

ArrayGeometryMath+2

Acceptance: 74.6%

#1037Easy

Valid Boomerang

ArrayGeometryMath

Acceptance: 39.9%

#1046Easy

Last Stone Weight

ArrayHeap (Priority Queue)

Acceptance: 66.4%

#1047Easy

Remove All Adjacent Duplicates In String

StackString

Acceptance: 73.6%

#1050Easy

Actors and Directors Who Cooperated At Least Three Times

Database

Acceptance: 70.3%

#1051Easy

Height Checker

ArrayCounting SortSorting

Acceptance: 81.6%

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Master DSA with Step-by-Step Solutions

Each solution article on FleetCode breaks down the problem into multiple approaches, from brute force to optimal, with detailed explanations and code in Python, Java, C++ and more. Understanding why an approach works - not just copying code - is what separates candidates who clear interviews from those who don't.

How to Use These Solutions

Try the problem first: Spend at least 20 minutes before reading the solution
Read all approaches: Start from brute force to understand the problem fully, then study the optimized solution
Understand the complexity: Pay attention to time and space analysis for each approach
Code it yourself: After understanding the approach, close the solution and implement from memory
Revisit after a week: Spaced repetition helps retain problem-solving patterns