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
1362. Closest Divisors	Medium	64.3%	Math	Read
1364. Number of Trusted Contacts of a Customer	Medium	74.9%	Database	Read
1366. Rank Teams by Votes	Medium	60.1%	Array Counting+3	Read
1367. Linked List in Binary Tree	Medium	52.1%	Binary Tree Depth-First Search+2	Read
1371. Find the Longest Substring Containing Vowels in Even Counts	Medium	75.7%	Bit Manipulation Hash Table+2	Read
1372. Longest ZigZag Path in a Binary Tree	Medium	67.0%	Binary Tree Depth-First Search+2	Read
1375. Number of Times Binary String Is Prefix-Aligned	Medium	65.8%	Array	Read
1376. Time Needed to Inform All Employees	Medium	60.6%	Breadth-First Search Depth-First Search+1	Read
1381. Design a Stack With Increment Operation	Medium	79.9%	Array Design+1	Read
1382. Balance a Binary Search Tree	Medium	86.3%	Binary Search Tree Binary Tree+4	Read
1386. Cinema Seat Allocation	Medium	56.8%	Array Bit Manipulation+2	Read
1387. Sort Integers by The Power Value	Medium	71.6%	Dynamic Programming Memoization+1	Read
1390. Four Divisors	Medium	56.6%	Array Math	Read
1391. Check if There is a Valid Path in a Grid	Medium	64.5%	Array Breadth-First Search+3	Read
1393. Capital Gain/Loss	Medium	85.3%	Database	Read
1395. Count Number of Teams	Medium	70.1%	Array Binary Indexed Tree+2	Read
1396. Design Underground System	Medium	74.8%	Design Hash Table+1	Read
1398. Customers Who Bought Products A and B but Not C	Medium	72.3%	Database	Read
1400. Construct K Palindrome Strings	Medium	68.6%	Counting Greedy+2	Read
1401. Circle and Rectangle Overlapping	Medium	67.4%	Geometry Math	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
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
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
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
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
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
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
1438. Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit	Medium	58.1%	Array Heap (Priority Queue)+4	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
1445. Apples & Oranges	Medium	86.0%	Database	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
1451. Rearrange Words in a Sentence	Medium	67.5%	Sorting String	Read
1452. People Whose List of Favorite Companies Is Not a Subset of Another List	Medium	60.6%	Array Hash Table+1	Read
1454. Active Users	Medium	36.7%	Database	Read
1456. Maximum Number of Vowels in a Substring of Given Length	Medium	63.0%	Sliding Window String	Read
1457. Pseudo-Palindromic Paths in a Binary Tree	Medium	68.3%	Binary Tree Bit Manipulation+3	Read
1459. Rectangles Area	Medium	68.5%	Database	Read
1461. Check If a String Contains All Binary Codes of Size K	Medium	61.5%	Bit Manipulation Hash Function+3	Read

#1362Medium

Closest Divisors

Math

Acceptance: 64.3%

#1364Medium

Number of Trusted Contacts of a Customer

Database

Acceptance: 74.9%

#1366Medium

Rank Teams by Votes

ArrayCountingHash Table+2

Acceptance: 60.1%

#1367Medium

Linked List in Binary Tree

Binary TreeDepth-First SearchLinked List+1

Acceptance: 52.1%

#1371Medium

Find the Longest Substring Containing Vowels in Even Counts

Bit ManipulationHash TablePrefix Sum+1

Acceptance: 75.7%

#1372Medium

Longest ZigZag Path in a Binary Tree

Binary TreeDepth-First SearchDynamic Programming+1

Acceptance: 67.0%

#1375Medium

Number of Times Binary String Is Prefix-Aligned

Array

Acceptance: 65.8%

#1376Medium

Time Needed to Inform All Employees

Breadth-First SearchDepth-First SearchTree

Acceptance: 60.6%

#1381Medium

Design a Stack With Increment Operation

ArrayDesignStack

Acceptance: 79.9%

#1382Medium

Balance a Binary Search Tree

Binary Search TreeBinary TreeDepth-First Search+3

Acceptance: 86.3%

#1386Medium

Cinema Seat Allocation

ArrayBit ManipulationGreedy+1

Acceptance: 56.8%

#1387Medium

Sort Integers by The Power Value

Dynamic ProgrammingMemoizationSorting

Acceptance: 71.6%

#1390Medium

Four Divisors

ArrayMath

Acceptance: 56.6%

#1391Medium

Check if There is a Valid Path in a Grid

ArrayBreadth-First SearchDepth-First Search+2

Acceptance: 64.5%

#1393Medium

Capital Gain/Loss

Database

Acceptance: 85.3%

#1395Medium

Count Number of Teams

ArrayBinary Indexed TreeDynamic Programming+1

Acceptance: 70.1%

#1396Medium

Design Underground System

DesignHash TableString

Acceptance: 74.8%

#1398Medium

Customers Who Bought Products A and B but Not C

Database

Acceptance: 72.3%

#1400Medium

Construct K Palindrome Strings

CountingGreedyHash Table+1

Acceptance: 68.6%

#1401Medium

Circle and Rectangle Overlapping

GeometryMath

Acceptance: 67.4%

#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%

#1409Medium

Queries on a Permutation With Key

ArrayBinary Indexed TreeSimulation

Acceptance: 84.9%

#1410Medium

HTML Entity Parser

Hash TableString

Acceptance: 50.0%

#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%

#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%

#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%

#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%

#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%

#1438Medium

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

ArrayHeap (Priority Queue)Monotonic Queue+3

Acceptance: 58.1%

#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%

#1445Medium

Apples & Oranges

Database

Acceptance: 86.0%

#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%

#1451Medium

Rearrange Words in a Sentence

SortingString

Acceptance: 67.5%

#1452Medium

People Whose List of Favorite Companies Is Not a Subset of Another List

ArrayHash TableString

Acceptance: 60.6%

#1454Medium

Active Users

Database

Acceptance: 36.7%

#1456Medium

Maximum Number of Vowels in a Substring of Given Length

Sliding WindowString

Acceptance: 63.0%

#1457Medium

Pseudo-Palindromic Paths in a Binary Tree

Binary TreeBit ManipulationBreadth-First Search+2

Acceptance: 68.3%

#1459Medium

Rectangles Area

Database

Acceptance: 68.5%

#1461Medium

Check If a String Contains All Binary Codes of Size K

Bit ManipulationHash FunctionHash Table+2

Acceptance: 61.5%

1 2 315 16 1741 42 43

Page 16 of 43

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