Array Interview Questions

Array Hash Table

Rank

#3594MediumFrequency: 100%

Identify the Largest Outlier in an Array

Array Hash Table Counting Enumeration

Rank

#3613MediumFrequency: 100%

Maximize Amount After Two Days of Conversions

Array String Depth-First Search Breadth-First Search Graph

Rank

#49MediumFrequency: 100%

Group Anagrams

Array Hash Table String Sorting

Rank

#1306EasyFrequency: 100%

Minimum Absolute Difference

Array Hash Table Two Pointers Binary Search Sorting

Array Sorting

Rank

#532MediumFrequency: 100%

K-diff Pairs in an Array

Asked at Salesforce

Rank

#286MediumFrequency: 100%

Walls and Gates

Array Breadth-First Search Matrix

Rank

#1171MediumFrequency: 100%

Shortest Path in Binary Matrix

Asked at Airbnb

Array Breadth-First Search Matrix

Rank

#362MediumFrequency: 100%

Design Hit Counter

Array Binary Search Design Queue Data Stream

Rank

#658MediumFrequency: 96%

Find K Closest Elements

Array Two Pointers Binary Search Sliding Window Sorting Heap (Priority Queue)

#10

Rank

#833HardFrequency: 95%

Bus Routes

Array Hash Table Breadth-First Search

#11

Rank

#348MediumFrequency: 93%

Design Tic-Tac-Toe

Array Hash Table Design Matrix Simulation

#12

Rank

#88EasyFrequency: 92%

Merge Sorted Array

#13

Rank

#215MediumFrequency: 92%

Kth Largest Element in an Array

Array Divide and Conquer Sorting Heap (Priority Queue)Quickselect

#14

Rank

#1046MediumFrequency: 88%

Max Consecutive Ones III

Array Binary Search Sliding Window Prefix Sum

#15

Rank

#200MediumFrequency: 88%

Number of Islands

Asked at Salesforce

Array Depth-First Search Breadth-First Search Union Find Matrix

#16

Rank

#300MediumFrequency: 88%

Longest Increasing Subsequence

Asked at Salesforce

Array Binary Search Dynamic Programming

#17

Rank

#912MediumFrequency: 87%

Random Pick with Weight

Array Math Binary Search Prefix Sum Randomized

#18

Rank

#238MediumFrequency: 87%

Product of Array Except Self

Array Prefix Sum

#19

Rank

#322MediumFrequency: 87%

Coin Change

Array Dynamic Programming Breadth-First Search

#20

Rank

#1478MediumFrequency: 87%

Maximum Number of Events That Can Be Attended

Array Greedy Sorting Heap (Priority Queue)

#21

Rank

#621MediumFrequency: 85%

Task Scheduler

Array Hash Table Greedy Sorting Heap (Priority Queue)Counting

#22

Rank

#162MediumFrequency: 85%

Find Peak Element

#23

Rank

#198MediumFrequency: 84%

House Robber

#24

Rank

#213MediumFrequency: 84%

House Robber II

#25

Rank

#1352HardFrequency: 83%

Maximum Profit in Job Scheduling

Array Binary Search Dynamic Programming Sorting

#26

Rank

#560MediumFrequency: 81%

Subarray Sum Equals K

Array Hash Table Prefix Sum

#27

Rank

#53MediumFrequency: 79%

Maximum Subarray

Array Divide and Conquer Dynamic Programming

#28

Rank

#269HardFrequency: 79%

Alien Dictionary

Array String Depth-First Search Breadth-First Search Graph Topological Sort

#29

Rank

#305HardFrequency: 79%

Number of Islands II

Array Hash Table Union Find

#30

Rank

#347MediumFrequency: 76%

Top K Frequent Elements

Array Hash Table Divide and Conquer Sorting Heap (Priority Queue)Bucket Sort Counting Quickselect

#31

Rank

#1713MediumFrequency: 76%

Dot Product of Two Sparse Vectors

Array Hash Table Two Pointers Design

#32

Rank

#42HardFrequency: 74%

Trapping Rain Water

Array Two Pointers Dynamic Programming Stack Monotonic Stack

#33

Rank

#3654MediumFrequency: 74%

Minimum Array Sum

#34

Rank

#27EasyFrequency: 73%

Remove Element

#35

Rank

#329HardFrequency: 73%

Longest Increasing Path in a Matrix

Array Dynamic Programming Depth-First Search Breadth-First Search Graph Topological Sort Memoization Matrix

#36

Rank

#907MediumFrequency: 73%

Koko Eating Bananas

#37

Rank

#1397MediumFrequency: 73%

Search Suggestions System

Array String Binary Search Trie Sorting Heap (Priority Queue)

#38

Rank

#1783MediumFrequency: 73%

Ways to Make a Fair Array

Array Prefix Sum

#39

Rank

#56MediumFrequency: 72%

Merge Intervals

Array Sorting

#40

Rank

#39MediumFrequency: 72%

Combination Sum

Asked at TikTok

Array Hash Table String Dynamic Programming Trie Memoization

#41

Rank

#139MediumFrequency: 72%

Word Break

Asked at TikTok

#42

Rank

#381HardFrequency: 72%

Insert Delete GetRandom O(1) - Duplicates allowed

Array Hash Table Math Design Randomized

#43

Rank

#605EasyFrequency: 72%

Can Place Flowers

Array Greedy

#44

Rank

#121EasyFrequency: 69%

Best Time to Buy and Sell Stock

#45

Rank

#1108MediumFrequency: 69%

Analyze User Website Visit Pattern

Array Hash Table Sorting

#46

Rank

#1028MediumFrequency: 69%

Interval List Intersections

#47

Rank

#1014MediumFrequency: 68%

K Closest Points to Origin

Array Math Divide and Conquer Geometry Sorting Heap (Priority Queue)Quickselect

#48

Rank

#4HardFrequency: 67%

Median of Two Sorted Arrays

Array Binary Search Divide and Conquer

#49

Rank

#1085MediumFrequency: 67%

The Earliest Moment When Everyone Become Friends

Array Union Find Sorting

#50

Rank

#3639MediumFrequency: 67%

Zero Array Transformation I

Array Prefix Sum

#51

Rank

#3647MediumFrequency: 67%

Zero Array Transformation III

Array Greedy Sorting Heap (Priority Queue)Prefix Sum

#52

Rank

#136EasyFrequency: 66%

Single Number

Array Bit Manipulation

#53

Rank

#283EasyFrequency: 66%

Move Zeroes

#54

Rank

#733EasyFrequency: 66%

Flood Fill

Array Depth-First Search Breadth-First Search Matrix

#55

Rank

#2089MediumFrequency: 66%

Maximum Matrix Sum

Array Greedy Matrix

#56

Rank

#2267HardFrequency: 64%

Minimum Difference in Sums After Removal of Elements

Array Dynamic Programming Heap (Priority Queue)

#57

Rank

#78MediumFrequency: 64%

Subsets

Array Backtracking Bit Manipulation

#58

Rank

#1909MediumFrequency: 64%

Buildings With an Ocean View

Array Stack Monotonic Stack

#59

Rank

#54MediumFrequency: 63%

Spiral Matrix

Array Matrix Simulation

#60

Rank

#79MediumFrequency: 63%

Word Search

Array String Backtracking Matrix

#61

Rank

#399MediumFrequency: 63%

Evaluate Division

Array String Depth-First Search Breadth-First Search Union Find Graph Shortest Path

#62

Rank

#772MediumFrequency: 63%

Construct Quad Tree

Array Divide and Conquer Tree Matrix

#63

Rank

#1019EasyFrequency: 63%

Squares of a Sorted Array

#64

Rank

#1549MediumFrequency: 63%

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

Array Queue Sliding Window Heap (Priority Queue)Ordered Set Monotonic Queue

#65

Rank

#34MediumFrequency: 63%

Find First and Last Position of Element in Sorted Array

#66

Rank

#40MediumFrequency: 63%

Combination Sum II

#67

Rank

#152MediumFrequency: 63%

Maximum Product Subarray

#68

Rank

#244MediumFrequency: 63%

Shortest Word Distance II

Array Hash Table Two Pointers String Design

#69

Rank

#31MediumFrequency: 62%

Next Permutation

#70

Rank

#346EasyFrequency: 62%

Moving Average from Data Stream

Array Design Queue Data Stream

#71

Rank

#721MediumFrequency: 62%

Accounts Merge

Array Hash Table String Depth-First Search Breadth-First Search Union Find Sorting

#72

Rank

#253MediumFrequency: 62%

Meeting Rooms II

Asked at TikTok

Array Two Pointers Greedy Sorting Heap (Priority Queue)Prefix Sum

#73

Rank

#2868MediumFrequency: 60%

Continuous Subarrays

Array Queue Sliding Window Heap (Priority Queue)Ordered Set Monotonic Queue

#74

Rank

#2891MediumFrequency: 60%

Maximum Beauty of an Array After Applying Operation

Array Binary Search Sliding Window Sorting

#75

Rank

#15MediumFrequency: 60%

3Sum

#76

Rank

#55MediumFrequency: 60%

Jump Game

Array Dynamic Programming Greedy

#77

Rank

#854HardFrequency: 60%

Making A Large Island

Array Depth-First Search Breadth-First Search Union Find Matrix

#78

Rank

#1646EasyFrequency: 57%

Kth Missing Positive Number

#79

Rank

#2164MediumFrequency: 56%

Two Best Non-Overlapping Events

Array Binary Search Dynamic Programming Sorting Heap (Priority Queue)

#80

Rank

#18MediumFrequency: 55%

4Sum

#81

Rank

#33MediumFrequency: 55%

Search in Rotated Sorted Array

#82

Rank

#90MediumFrequency: 55%

Subsets II

Array Backtracking Bit Manipulation

#83

Rank

#128MediumFrequency: 55%

Longest Consecutive Sequence

Array Hash Table Union Find

#84

Rank

#167MediumFrequency: 55%

Two Sum II - Input Array Is Sorted

Array Two Pointers Binary Search

#85

Rank

#169EasyFrequency: 55%

Majority Element

Array Hash Table Divide and Conquer Sorting Counting

#86

Rank

#1036MediumFrequency: 55%

Rotting Oranges

Array Breadth-First Search Matrix

#87

Rank

#1147MediumFrequency: 55%

Flip Columns For Maximum Number of Equal Rows

Array Hash Table Matrix

#88

Rank

#1468EasyFrequency: 55%

Check If N and Its Double Exist

Array Hash Table Two Pointers Binary Search Sorting

#89

Rank

#2711HardFrequency: 55%

Minimum Time to Visit a Cell In a Grid

Array Breadth-First Search Graph Heap (Priority Queue)Matrix Shortest Path

#90

Rank

#3555EasyFrequency: 55%

Final Array State After K Multiplication Operations I

Array Math Heap (Priority Queue)Simulation

#91

Rank

#26EasyFrequency: 53%

Remove Duplicates from Sorted Array

#92

Rank

#35EasyFrequency: 53%

Search Insert Position

#93

Rank

#380MediumFrequency: 51%

Insert Delete GetRandom O(1)

Array Hash Table Math Design Randomized

#94

Rank

#1056MediumFrequency: 51%

Capacity To Ship Packages Within D Days

#95

Rank

#51HardFrequency: 48%

N-Queens

#96

Rank

#118EasyFrequency: 48%

Pascal's Triangle

#97

Rank

#976MediumFrequency: 48%

Minimum Area Rectangle

Array Hash Table Math Geometry Sorting

#98

Rank

#1886MediumFrequency: 48%

Minimum Limit of Balls in a Bag

#99

Rank

#2232MediumFrequency: 48%

Adding Spaces to a String

Array Two Pointers String Simulation

#100

Rank

#2692EasyFrequency: 48%

Take Gifts From the Richest Pile

Array Heap (Priority Queue)Simulation

#101

Rank

#3643MediumFrequency: 48%

Zero Array Transformation II

Array Binary Search Prefix Sum

#102

Rank

#48MediumFrequency: 47%

Rotate Image

Array Math Matrix

#103

Rank

#84HardFrequency: 45%

Largest Rectangle in Histogram

Array Stack Monotonic Stack

#104

Rank

#122MediumFrequency: 45%

Best Time to Buy and Sell Stock II

Array Dynamic Programming Greedy

#105

Rank

#239HardFrequency: 45%

Sliding Window Maximum

Array Queue Sliding Window Heap (Priority Queue)Monotonic Queue

#106

Rank

#373MediumFrequency: 45%

Find K Pairs with Smallest Sums

Array Heap (Priority Queue)

#107

Rank

#1034HardFrequency: 45%

Subarrays with K Different Integers

Array Hash Table Sliding Window Counting

#108

Rank

#249MediumFrequency: 43%

Group Shifted Strings

Array Hash Table String

#109

Rank

#325MediumFrequency: 43%

Maximum Size Subarray Sum Equals k

Array Hash Table Prefix Sum

#110

Rank

#498MediumFrequency: 43%

Diagonal Traverse

Array Matrix Simulation

#111

Rank

#523MediumFrequency: 43%

Continuous Subarray Sum

Array Hash Table Math Prefix Sum

#112

Rank

#777EasyFrequency: 43%

Toeplitz Matrix

Array Matrix

#113

Rank

#11MediumFrequency: 42%

Container With Most Water

Array Two Pointers Greedy

#114

Rank

#46MediumFrequency: 42%

Permutations

#115

Rank

#63MediumFrequency: 42%

Unique Paths II

Array Dynamic Programming Matrix

#116

Rank

#66EasyFrequency: 42%

Plus One

Array Math

#117

Rank

#75MediumFrequency: 42%

Sort Colors

#118

Rank

#179MediumFrequency: 42%

Largest Number

Array String Greedy Sorting

#119

Rank

#268EasyFrequency: 42%

Missing Number

Array Hash Table Math Binary Search Bit Manipulation Sorting

#120

Rank

#410HardFrequency: 42%

Split Array Largest Sum

Array Binary Search Dynamic Programming Greedy Prefix Sum

#121

Rank

#518MediumFrequency: 42%

Coin Change II

#122

Rank

#739MediumFrequency: 42%

Daily Temperatures

Array Stack Monotonic Stack

#123

Rank

#987MediumFrequency: 42%

Reveal Cards In Increasing Order

Array Queue Sorting Simulation

#124

Rank

#1330MediumFrequency: 42%

Longest Arithmetic Subsequence of Given Difference

Array Hash Table Dynamic Programming

#125

Rank

#1966MediumFrequency: 42%

Frequency of the Most Frequent Element

Array Binary Search Greedy Sliding Window Sorting Prefix Sum

#126

Rank

#3681MediumFrequency: 42%

Maximum Area Rectangle With Point Constraints I

Array Math Binary Indexed Tree Segment Tree Geometry Sorting Enumeration

#127

Rank

#163EasyFrequency: 37%

Missing Ranges

Array

#128

Rank

#378MediumFrequency: 37%

Kth Smallest Element in a Sorted Matrix

Array Binary Search Sorting Heap (Priority Queue)Matrix

#129

Rank

#735MediumFrequency: 37%

Asteroid Collision

Array Stack Simulation

#130

Rank

#852MediumFrequency: 37%

Friends Of Appropriate Ages

Array Two Pointers Binary Search Sorting

#131

Rank

#36MediumFrequency: 36%

Valid Sudoku

Array Hash Table Matrix

#132

Rank

#64MediumFrequency: 36%

Minimum Path Sum

Array Dynamic Programming Matrix

#133

Rank

#80MediumFrequency: 36%

Remove Duplicates from Sorted Array II

#134

Rank

#134MediumFrequency: 36%

Gas Station

Array Greedy

#135

Rank

#188HardFrequency: 36%

Best Time to Buy and Sell Stock IV

#136

Rank

#41HardFrequency: 33%

First Missing Positive

Array Hash Table

#137

Rank

#45MediumFrequency: 33%

Jump Game II