Hash Table Interview Questions

Array Hash Table

Rank

#3594MediumFrequency: 100%

Identify the Largest Outlier in an Array

Array Hash Table Counting Enumeration

Rank

#3638HardFrequency: 100%

Minimum Operations to Make Character Frequencies Equal

Asked at TikTok

Hash Table String Dynamic Programming Counting Enumeration

Rank

#49MediumFrequency: 100%

Group Anagrams

Asked at Oracle

Array Hash Table String Sorting

Rank

#532MediumFrequency: 100%

K-diff Pairs in an Array

Asked at Salesforce

Array Hash Table Two Pointers Binary Search Sorting

Rank

#1423MediumFrequency: 100%

Maximum Number of Occurrences of a Substring

Asked at Salesforce

Hash Table Linked List Design Doubly-Linked List

Rank

#146MediumFrequency: 100%

LRU Cache

Asked at Flipkart

Rank

#314MediumFrequency: 97%

Binary Tree Vertical Order Traversal

Hash Table Tree Depth-First Search Breadth-First Search Sorting Binary Tree

Rank

#833HardFrequency: 95%

Bus Routes

Asked at Uber

Array Hash Table Breadth-First Search

Rank

#348MediumFrequency: 93%

Design Tic-Tac-Toe

Asked at Databricks

Array Hash Table Design Matrix Simulation

#10

Rank

#1790MediumFrequency: 91%

Lowest Common Ancestor of a Binary Tree III

Hash Table Two Pointers Tree Binary Tree

#11

Rank

#460HardFrequency: 88%

LFU Cache

Asked at Salesforce

Hash Table Linked List Design Doubly-Linked List

#12

Rank

#621MediumFrequency: 85%

Task Scheduler

Array Hash Table Greedy Sorting Heap (Priority Queue)Counting

#13

Rank

#3MediumFrequency: 84%

Longest Substring Without Repeating Characters

#14

Rank

#560MediumFrequency: 81%

Subarray Sum Equals K

Array Hash Table Prefix Sum

#15

Rank

#305HardFrequency: 79%

Number of Islands II

Asked at Uber

Array Hash Table Union Find

#16

Rank

#347MediumFrequency: 76%

Top K Frequent Elements

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

#17

Rank

#1713MediumFrequency: 76%

Dot Product of Two Sparse Vectors

Array Hash Table Two Pointers Design

#18

Rank

#1915EasyFrequency: 73%

Check if One String Swap Can Make Strings Equal

Asked at DoorDash

Hash Table String Counting

#19

Rank

#778MediumFrequency: 72%

Reorganize String

Hash Table String Greedy Sorting Heap (Priority Queue)Counting

#20

Rank

#3710HardFrequency: 72%

Design an Array Statistics Tracker

Hash Table Binary Search Design Queue Heap (Priority Queue)Data Stream Ordered Set

#21

Rank

#139MediumFrequency: 72%

Word Break

Asked at TikTok

Array Hash Table String Dynamic Programming Trie Memoization

#22

Rank

#381HardFrequency: 72%

Insert Delete GetRandom O(1) - Duplicates allowed

Asked at LinkedIn

Array Hash Table Math Design Randomized

#23

Rank

#127HardFrequency: 71%

Word Ladder

Asked at Apple

Hash Table String Breadth-First Search

#24

Rank

#1108MediumFrequency: 69%

Analyze User Website Visit Pattern

Array Hash Table Sorting

#25

Rank

#138MediumFrequency: 67%

Copy List with Random Pointer

Hash Table Linked List

#26

Rank

#893MediumFrequency: 64%

All Nodes Distance K in Binary Tree

Hash Table Tree Depth-First Search Breadth-First Search Binary Tree

#27

Rank

#244MediumFrequency: 63%

Shortest Word Distance II

Asked at LinkedIn

Array Hash Table Two Pointers String Design

#28

Rank

#432HardFrequency: 63%

All O`one Data Structure

Asked at LinkedIn

Hash Table Linked List Design Doubly-Linked List

#29

Rank

#721MediumFrequency: 62%

Accounts Merge

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

#30

Rank

#694MediumFrequency: 62%

Number of Distinct Islands

Asked at TikTok

Hash Table Depth-First Search Breadth-First Search Union Find Hash Function

#31

Rank

#76HardFrequency: 60%

Minimum Window Substring

#32

Rank

#133MediumFrequency: 60%

Clone Graph

Hash Table Depth-First Search Breadth-First Search Graph

#33

Rank

#807MediumFrequency: 60%

Custom Sort String

Hash Table String Sorting

#34

Rank

#1029HardFrequency: 60%

Vertical Order Traversal of a Binary Tree

Hash Table Tree Depth-First Search Breadth-First Search Sorting Binary Tree

#35

Rank

#17MediumFrequency: 56%

Letter Combinations of a Phone Number

Hash Table String Backtracking

#36

Rank

#12MediumFrequency: 55%

Integer to Roman

Hash Table Math String

#37

Rank

#128MediumFrequency: 55%

Longest Consecutive Sequence

Array Hash Table Union Find

#38

Rank

#169EasyFrequency: 55%

Majority Element

Array Hash Table Divide and Conquer Sorting Counting

#39

Rank

#205EasyFrequency: 55%

Isomorphic Strings

Hash Table String

#40

Rank

#291MediumFrequency: 55%

Word Pattern II

Hash Table String Backtracking

#41

Rank

#567MediumFrequency: 55%

Permutation in String

Hash Table Two Pointers String Sliding Window

#42

Rank

#1147MediumFrequency: 55%

Flip Columns For Maximum Number of Equal Rows

Array Hash Table Matrix

#43

Rank

#1468EasyFrequency: 55%

Check If N and Its Double Exist

Array Hash Table Two Pointers Binary Search Sorting

#44

Rank

#141EasyFrequency: 53%

Linked List Cycle

Hash Table Linked List Two Pointers

#45

Rank

#2300MediumFrequency: 53%

Construct String With Repeat Limit

Hash Table String Greedy Heap (Priority Queue)Counting

#46

Rank

#380MediumFrequency: 51%

Insert Delete GetRandom O(1)

Array Hash Table Math Design Randomized

#47

Rank

#387EasyFrequency: 51%

First Unique Character in a String

Hash Table String Queue Counting

#48

Rank

#398MediumFrequency: 51%

Random Pick Index

Hash Table Math Reservoir Sampling Randomized

#49

Rank

#976MediumFrequency: 48%

Minimum Area Rectangle

Array Hash Table Math Geometry Sorting

#50

Rank

#126HardFrequency: 45%

Word Ladder II

Hash Table String Backtracking Breadth-First Search

#51

Rank

#1034HardFrequency: 45%

Subarrays with K Different Integers

Array Hash Table Sliding Window Counting

#52

Rank

#3410HardFrequency: 45%

Find Longest Self-Contained Substring

Hash Table String Binary Search Prefix Sum

#53

Rank

#249MediumFrequency: 43%

Group Shifted Strings

Array Hash Table String

#54

Rank

#325MediumFrequency: 43%

Maximum Size Subarray Sum Equals k

Array Hash Table Prefix Sum

#55

Rank

#523MediumFrequency: 43%

Continuous Subarray Sum

Array Hash Table Math Prefix Sum

#56

Rank

#13EasyFrequency: 42%

Roman to Integer

Hash Table Math String

#57

Rank

#268EasyFrequency: 42%

Missing Number

Array Hash Table Math Binary Search Bit Manipulation Sorting

#58

Rank

#359EasyFrequency: 42%

Logger Rate Limiter

Hash Table Design Data Stream

#59

Rank

#383EasyFrequency: 42%

Ransom Note

Hash Table String Counting

#60

Rank

#424MediumFrequency: 42%

Longest Repeating Character Replacement

#61

Rank

#1330MediumFrequency: 42%

Longest Arithmetic Subsequence of Given Difference

Array Hash Table Dynamic Programming

#62

Rank

#36MediumFrequency: 36%

Valid Sudoku

Array Hash Table Matrix

#63

Rank

#41HardFrequency: 33%

First Missing Positive