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
1232. Check If It Is a Straight Line	Easy	40.1%	Array Geometry+1	Read
1241. Number of Comments per Post	Easy	66.0%	Database	Read
1243. Array Transformation	Easy	53.6%	Array Simulation	Read
1251. Average Selling Price	Easy	37.1%	Database	Read
1252. Cells with Odd Values in a Matrix	Easy	79.7%	Array Math+1	Read
1260. Shift 2D Grid	Easy	74.3%	Array Matrix+1	Read
1266. Minimum Time Visiting All Points	Easy	84.8%	Array Geometry+1	Read
1271. Hexspeak	Easy	58.2%	Math String	Read
1275. Find Winner on a Tic Tac Toe Game	Easy	54.6%	Array Hash Table+2	Read
1279. Traffic Light Controlled Intersection	Easy	72.8%	Concurrency	Read
1280. Students and Examinations	Easy	59.6%	Database	Read
1281. Subtract the Product and Sum of Digits of an Integer	Easy	86.6%	Math	Read
1287. Element Appearing More Than 25% In Sorted Array	Easy	61.5%	Array	Read
1290. Convert Binary Number in a Linked List to Integer	Easy	82.3%	Linked List Math	Read
1294. Weather Type in Each Country	Easy	66.8%	Database	Read
1295. Find Numbers with Even Number of Digits	Easy	79.7%	Array Math	Read
1299. Replace Elements with Greatest Element on Right Side	Easy	72.6%	Array	Read
1303. Find the Team Size	Easy	89.6%	Database	Read
1304. Find N Unique Integers Sum up to Zero	Easy	78.5%	Array Math	Read
1309. Decrypt String from Alphabet to Integer Mapping	Easy	80.6%	String	Read
1313. Decompress Run-Length Encoded List	Easy	85.9%	Array	Read
1317. Convert Integer to the Sum of Two No-Zero Integers	Easy	59.1%	Math	Read
1322. Ads Performance	Easy	59.4%	Database	Read
1323. Maximum 69 Number	Easy	84.5%	Greedy Math	Read
1327. List the Products Ordered in a Period	Easy	71.6%	Database	Read
1331. Rank Transform of an Array	Easy	73.9%	Array Hash Table+1	Read
1332. Remove Palindromic Subsequences	Easy	77.1%	String Two Pointers	Read
1337. The K Weakest Rows in a Matrix	Easy	74.3%	Array Binary Search+3	Read
1342. Number of Steps to Reduce a Number to Zero	Easy	86.0%	Bit Manipulation Math	Read
1346. Check If N and Its Double Exist	Easy	41.7%	Array Binary Search+3	Read
1350. Students With Invalid Departments	Easy	89.8%	Database	Read
1351. Count Negative Numbers in a Sorted Matrix	Easy	79.6%	Array Binary Search+1	Read
1356. Sort Integers by The Number of 1 Bits	Easy	82.3%	Array Bit Manipulation+2	Read
1360. Number of Days Between Two Dates	Easy	53.1%	Math String	Read
1365. How Many Numbers Are Smaller Than the Current Number	Easy	87.0%	Array Counting+2	Read
1370. Increasing Decreasing String	Easy	77.3%	Counting Hash Table+1	Read
1374. Generate a String With Characters That Have Odd Counts	Easy	78.1%	String	Read
1378. Replace Employee ID With The Unique Identifier	Easy	83.6%	Database	Read
1379. Find a Corresponding Node of a Binary Tree in a Clone of That Tree	Easy	85.9%	Binary Tree Breadth-First Search+2	Read
1380. Lucky Numbers in a Matrix	Easy	79.9%	Array Matrix	Read
1385. Find the Distance Value Between Two Arrays	Easy	72.1%	Array Binary Search+2	Read
1389. Create Target Array in the Given Order	Easy	86.6%	Array Simulation	Read
1394. Find Lucky Integer in an Array	Easy	75.5%	Array Counting+1	Read
1399. Count Largest Group	Easy	74.7%	Hash Table Math	Read
1403. Minimum Subsequence in Non-Increasing Order	Easy	73.7%	Array Greedy+1	Read
1407. Top Travellers	Easy	57.3%	Database	Read
1408. String Matching in an Array	Easy	69.8%	Array String+1	Read
1413. Minimum Value to Get Positive Step by Step Sum	Easy	65.1%	Array Prefix Sum	Read
1417. Reformat The String	Easy	52.3%	String	Read
1421. NPV Queries	Easy	82.8%	Database	Read

#1232Easy

Check If It Is a Straight Line

ArrayGeometryMath

Acceptance: 40.1%

#1241Easy

Number of Comments per Post

Database

Acceptance: 66.0%

#1243Easy

Array Transformation

ArraySimulation

Acceptance: 53.6%

#1251Easy

Average Selling Price

Database

Acceptance: 37.1%

#1252Easy

Cells with Odd Values in a Matrix

ArrayMathSimulation

Acceptance: 79.7%

#1260Easy

Shift 2D Grid

ArrayMatrixSimulation

Acceptance: 74.3%

#1266Easy

Minimum Time Visiting All Points

ArrayGeometryMath

Acceptance: 84.8%

#1271Easy

Hexspeak

MathString

Acceptance: 58.2%

#1275Easy

Find Winner on a Tic Tac Toe Game

ArrayHash TableMatrix+1

Acceptance: 54.6%

#1279Easy

Traffic Light Controlled Intersection

Concurrency

Acceptance: 72.8%

#1280Easy

Students and Examinations

Database

Acceptance: 59.6%

#1281Easy

Subtract the Product and Sum of Digits of an Integer

Math

Acceptance: 86.6%

#1287Easy

Element Appearing More Than 25% In Sorted Array

Array

Acceptance: 61.5%

#1290Easy

Convert Binary Number in a Linked List to Integer

Linked ListMath

Acceptance: 82.3%

#1294Easy

Weather Type in Each Country

Database

Acceptance: 66.8%

#1295Easy

Find Numbers with Even Number of Digits

ArrayMath

Acceptance: 79.7%

#1299Easy

Replace Elements with Greatest Element on Right Side

Array

Acceptance: 72.6%

#1303Easy

Find the Team Size

Database

Acceptance: 89.6%

#1304Easy

Find N Unique Integers Sum up to Zero

ArrayMath

Acceptance: 78.5%

#1309Easy

Decrypt String from Alphabet to Integer Mapping

String

Acceptance: 80.6%

#1313Easy

Decompress Run-Length Encoded List

Array

Acceptance: 85.9%

#1317Easy

Convert Integer to the Sum of Two No-Zero Integers

Math

Acceptance: 59.1%

#1322Easy

Ads Performance

Database

Acceptance: 59.4%

#1323Easy

Maximum 69 Number

GreedyMath

Acceptance: 84.5%

#1327Easy

List the Products Ordered in a Period

Database

Acceptance: 71.6%

#1331Easy

Rank Transform of an Array

ArrayHash TableSorting

Acceptance: 73.9%

#1332Easy

Remove Palindromic Subsequences

StringTwo Pointers

Acceptance: 77.1%

#1337Easy

The K Weakest Rows in a Matrix

ArrayBinary SearchHeap (Priority Queue)+2

Acceptance: 74.3%

#1342Easy

Number of Steps to Reduce a Number to Zero

Bit ManipulationMath

Acceptance: 86.0%

#1346Easy

Check If N and Its Double Exist

ArrayBinary SearchHash Table+2

Acceptance: 41.7%

#1350Easy

Students With Invalid Departments

Database

Acceptance: 89.8%

#1351Easy

Count Negative Numbers in a Sorted Matrix

ArrayBinary SearchMatrix

Acceptance: 79.6%

#1356Easy

Sort Integers by The Number of 1 Bits

ArrayBit ManipulationCounting+1

Acceptance: 82.3%

#1360Easy

Number of Days Between Two Dates

MathString

Acceptance: 53.1%

#1365Easy

How Many Numbers Are Smaller Than the Current Number

ArrayCountingHash Table+1

Acceptance: 87.0%

#1370Easy

Increasing Decreasing String

CountingHash TableString

Acceptance: 77.3%

#1374Easy

Generate a String With Characters That Have Odd Counts

String

Acceptance: 78.1%

#1378Easy

Replace Employee ID With The Unique Identifier

Database

Acceptance: 83.6%

#1379Easy

Find a Corresponding Node of a Binary Tree in a Clone of That Tree

Binary TreeBreadth-First SearchDepth-First Search+1

Acceptance: 85.9%

#1380Easy

Lucky Numbers in a Matrix

ArrayMatrix

Acceptance: 79.9%

#1385Easy

Find the Distance Value Between Two Arrays

ArrayBinary SearchSorting+1

Acceptance: 72.1%

#1389Easy

Create Target Array in the Given Order

ArraySimulation

Acceptance: 86.6%

#1394Easy

Find Lucky Integer in an Array

ArrayCountingHash Table

Acceptance: 75.5%

#1399Easy

Count Largest Group

Hash TableMath

Acceptance: 74.7%

#1403Easy

Minimum Subsequence in Non-Increasing Order

ArrayGreedySorting

Acceptance: 73.7%

#1407Easy

Top Travellers

Database

Acceptance: 57.3%

#1408Easy

String Matching in an Array

ArrayStringString Matching

Acceptance: 69.8%

#1413Easy

Minimum Value to Get Positive Step by Step Sum

ArrayPrefix Sum

Acceptance: 65.1%

#1417Easy

Reformat The String

String

Acceptance: 52.3%

#1421Easy

NPV Queries

Database

Acceptance: 82.8%

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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