Solutions & Explanations

Browse 4,030+ detailed solutions with multiple approaches, code in Python, Java, C++ and more.

4,030 Solutions961 Easy2102 Medium967 Hard

Title	Difficulty	Acceptance	Topics	Solution
1401. Circle and Rectangle Overlapping	Medium	53.4%	Geometry Math	Read
1402. Reducing Dishes	Hard	76.8%	Array Dynamic Programming+2	Read
1403. Minimum Subsequence in Non-Increasing Order	Easy	73.7%	Array Greedy+1	Read
1404. Number of Steps to Reduce a Number in Binary Representation to One	Medium	63.8%	Bit Manipulation String	Read
1405. Longest Happy String	Medium	65.5%	Greedy Heap (Priority Queue)+1	Read
1406. Stone Game III	Hard	68.0%	Array Dynamic Programming+2	Read
1407. Top Travellers	Easy	57.3%	Database	Read
1408. String Matching in an Array	Easy	69.8%	Array String+1	Read
1409. Queries on a Permutation With Key	Medium	84.9%	Array Binary Indexed Tree+1	Read
1410. HTML Entity Parser	Medium	50.0%	Hash Table String	Read
1411. Number of Ways to Paint N × 3 Grid	Hard	80.6%	Dynamic Programming	Read
1412. Find the Quiet Students in All Exams	Hard	58.7%	Database	Read
1413. Minimum Value to Get Positive Step by Step Sum	Easy	65.1%	Array Prefix Sum	Read
1414. Find the Minimum Number of Fibonacci Numbers Whose Sum Is K	Medium	64.9%	Greedy Math	Read
1415. The k-th Lexicographical String of All Happy Strings of Length n	Medium	87.1%	Backtracking String	Read
1416. Restore The Array	Hard	47.2%	Dynamic Programming String	Read
1417. Reformat The String	Easy	52.3%	String	Read
1418. Display Table of Food Orders in a Restaurant	Medium	76.5%	Array Hash Table+3	Read
1419. Minimum Number of Frogs Croaking	Medium	51.2%	Counting String	Read
1420. Build Array Where You Can Find The Maximum Exactly K Comparisons	Hard	65.3%	Dynamic Programming Prefix Sum	Read
1421. NPV Queries	Easy	82.8%	Database	Read
1422. Maximum Score After Splitting a String	Easy	65.1%	Prefix Sum String	Read
1423. Maximum Points You Can Obtain from Cards	Medium	58.1%	Array Prefix Sum+1	Read
1424. Diagonal Traverse II	Medium	58.3%	Array Heap (Priority Queue)+1	Read
1425. Constrained Subsequence Sum	Hard	56.5%	Array Dynamic Programming+4	Read
1426. Counting Elements	Easy	60.3%	Array Hash Table	Read
1427. Perform String Shifts	Easy	56.0%	Array Math+1	Read
1428. Leftmost Column with at Least a One	Medium	55.3%	Array Binary Search+2	Read
1429. First Unique Number	Medium	57.8%	Array Data Stream+3	Read
1430. Check If a String Is a Valid Sequence from Root to Leaves Path in a Binary Tree	Medium	47.6%	Binary Tree Breadth-First Search+2	Read
1431. Kids With the Greatest Number of Candies	Easy	87.8%	Array	Read
1432. Max Difference You Can Get From Changing an Integer	Medium	48.8%	Greedy Math	Read
1433. Check If a String Can Break Another String	Medium	70.9%	Greedy Sorting+1	Read
1434. Number of Ways to Wear Different Hats to Each Other	Hard	46.4%	Array Bit Manipulation+2	Read
1435. Create a Session Bar Chart	Easy	74.9%	Database	Read
1436. Destination City	Easy	79.5%	Array Hash Table+1	Read
1437. Check If All 1's Are at Least Length K Places Away	Easy	64.3%	Array	Read
1438. Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit	Medium	58.1%	Array Heap (Priority Queue)+4	Read
1439. Find the Kth Smallest Sum of a Matrix With Sorted Rows	Hard	62.0%	Array Binary Search+2	Read
1440. Evaluate Boolean Expression	Medium	72.6%	Database	Read
1441. Build an Array With Stack Operations	Medium	81.0%	Array Simulation+1	Read
1442. Count Triplets That Can Form Two Arrays of Equal XOR	Medium	84.9%	Array Bit Manipulation+3	Read
1443. Minimum Time to Collect All Apples in a Tree	Medium	63.6%	Breadth-First Search Depth-First Search+2	Read
1444. Number of Ways of Cutting a Pizza	Hard	61.8%	Array Dynamic Programming+2	Read
1445. Apples & Oranges	Medium	86.0%	Database	Read
1446. Consecutive Characters	Easy	60.1%	String	Read
1447. Simplified Fractions	Medium	70.3%	Math Number Theory+1	Read
1448. Count Good Nodes in Binary Tree	Medium	73.8%	Binary Tree Breadth-First Search+2	Read
1449. Form Largest Integer With Digits That Add up to Target	Hard	49.6%	Array Dynamic Programming	Read
1450. Number of Students Doing Homework at a Given Time	Easy	76.3%	Array	Read

#1401Medium

Circle and Rectangle Overlapping

GeometryMath

Acceptance: 53.4%

#1402Hard

Reducing Dishes

ArrayDynamic ProgrammingGreedy+1

Acceptance: 76.8%

#1403Easy

Minimum Subsequence in Non-Increasing Order

ArrayGreedySorting

Acceptance: 73.7%

#1404Medium

Number of Steps to Reduce a Number in Binary Representation to One

Bit ManipulationString

Acceptance: 63.8%

#1405Medium

Longest Happy String

GreedyHeap (Priority Queue)String

Acceptance: 65.5%

#1406Hard

Stone Game III

ArrayDynamic ProgrammingGame Theory+1

Acceptance: 68.0%

#1407Easy

Top Travellers

Database

Acceptance: 57.3%

#1408Easy

String Matching in an Array

ArrayStringString Matching

Acceptance: 69.8%

#1409Medium

Queries on a Permutation With Key

ArrayBinary Indexed TreeSimulation

Acceptance: 84.9%

#1410Medium

HTML Entity Parser

Hash TableString

Acceptance: 50.0%

#1411Hard

Number of Ways to Paint N × 3 Grid

Dynamic Programming

Acceptance: 80.6%

#1412Hard

Find the Quiet Students in All Exams

Database

Acceptance: 58.7%

#1413Easy

Minimum Value to Get Positive Step by Step Sum

ArrayPrefix Sum

Acceptance: 65.1%

#1414Medium

Find the Minimum Number of Fibonacci Numbers Whose Sum Is K

GreedyMath

Acceptance: 64.9%

#1415Medium

The k-th Lexicographical String of All Happy Strings of Length n

BacktrackingString

Acceptance: 87.1%

#1416Hard

Restore The Array

Dynamic ProgrammingString

Acceptance: 47.2%

#1417Easy

Reformat The String

String

Acceptance: 52.3%

#1418Medium

Display Table of Food Orders in a Restaurant

ArrayHash TableOrdered Set+2

Acceptance: 76.5%

#1419Medium

Minimum Number of Frogs Croaking

CountingString

Acceptance: 51.2%

#1420Hard

Build Array Where You Can Find The Maximum Exactly K Comparisons

Dynamic ProgrammingPrefix Sum

Acceptance: 65.3%

#1421Easy

NPV Queries

Database

Acceptance: 82.8%

#1422Easy

Maximum Score After Splitting a String

Prefix SumString

Acceptance: 65.1%

#1423Medium

Maximum Points You Can Obtain from Cards

ArrayPrefix SumSliding Window

Acceptance: 58.1%

#1424Medium

Diagonal Traverse II

ArrayHeap (Priority Queue)Sorting

Acceptance: 58.3%

#1425Hard

Constrained Subsequence Sum

ArrayDynamic ProgrammingHeap (Priority Queue)+3

Acceptance: 56.5%

#1426Easy

Counting Elements

ArrayHash Table

Acceptance: 60.3%

#1427Easy

Perform String Shifts

ArrayMathString

Acceptance: 56.0%

#1428Medium

Leftmost Column with at Least a One

ArrayBinary SearchInteractive+1

Acceptance: 55.3%

#1429Medium

First Unique Number

ArrayData StreamDesign+2

Acceptance: 57.8%

#1430Medium

Check If a String Is a Valid Sequence from Root to Leaves Path in a Binary Tree

Binary TreeBreadth-First SearchDepth-First Search+1

Acceptance: 47.6%

#1431Easy

Kids With the Greatest Number of Candies

Array

Acceptance: 87.8%

#1432Medium

Max Difference You Can Get From Changing an Integer

GreedyMath

Acceptance: 48.8%

#1433Medium

Check If a String Can Break Another String

GreedySortingString

Acceptance: 70.9%

#1434Hard

Number of Ways to Wear Different Hats to Each Other

ArrayBit ManipulationBitmask+1

Acceptance: 46.4%

#1435Easy

Create a Session Bar Chart

Database

Acceptance: 74.9%

#1436Easy

Destination City

ArrayHash TableString

Acceptance: 79.5%

#1437Easy

Check If All 1's Are at Least Length K Places Away

Array

Acceptance: 64.3%

#1438Medium

Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit

ArrayHeap (Priority Queue)Monotonic Queue+3

Acceptance: 58.1%

#1439Hard

Find the Kth Smallest Sum of a Matrix With Sorted Rows

ArrayBinary SearchHeap (Priority Queue)+1

Acceptance: 62.0%

#1440Medium

Evaluate Boolean Expression

Database

Acceptance: 72.6%

#1441Medium

Build an Array With Stack Operations

ArraySimulationStack

Acceptance: 81.0%

#1442Medium

Count Triplets That Can Form Two Arrays of Equal XOR

ArrayBit ManipulationHash Table+2

Acceptance: 84.9%

#1443Medium

Minimum Time to Collect All Apples in a Tree

Breadth-First SearchDepth-First SearchHash Table+1

Acceptance: 63.6%

#1444Hard

Number of Ways of Cutting a Pizza

ArrayDynamic ProgrammingMatrix+1

Acceptance: 61.8%

#1445Medium

Apples & Oranges

Database

Acceptance: 86.0%

#1446Easy

Consecutive Characters

String

Acceptance: 60.1%

#1447Medium

Simplified Fractions

MathNumber TheoryString

Acceptance: 70.3%

#1448Medium

Count Good Nodes in Binary Tree

Binary TreeBreadth-First SearchDepth-First Search+1

Acceptance: 73.8%

#1449Hard

Form Largest Integer With Digits That Add up to Target

ArrayDynamic Programming

Acceptance: 49.6%

#1450Easy

Number of Students Doing Homework at a Given Time

Array

Acceptance: 76.3%

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Master DSA with Step-by-Step Solutions

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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