Quick Interview Prep - 25 Essential Problems

String Stack

Rank

#146MediumFrequency: 100%High Priority

LRU Cache

Asked at Apple

Rank

#833HardFrequency: 100%High Priority

Bus Routes

Array Hash Table Breadth-First Search

Rank

#716HardFrequency: 100%High Priority

Max Stack

Linked List Stack Design Doubly-Linked List Ordered Set

Rank

#2710MediumFrequency: 100%High Priority

Minimum Operations to Reduce an Integer to 0

Asked at Salesforce

Dynamic Programming Greedy Bit Manipulation

Rank

#286MediumFrequency: 100%High Priority

Walls and Gates

Asked at DoorDash

Array Breadth-First Search Matrix

Rank

#68HardFrequency: 100%High Priority

Text Justification

Array String Simulation

Rank

#1538MediumFrequency: 100%High Priority

Maximum Points You Can Obtain from Cards

Array Sliding Window Prefix Sum

Rank

#750HardFrequency: 100%High Priority

Contain Virus

Array Depth-First Search Breadth-First Search Matrix Simulation

#10

Rank

#6MediumFrequency: 100%High Priority

Zigzag Conversion

String

#11

Rank

#362MediumFrequency: 100%High Priority

Design Hit Counter

Array Binary Search Design Queue Data Stream

#12

Rank

#752MediumFrequency: 97.6%High Priority

IP to CIDR

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

String Bit Manipulation

#13

Rank

#200MediumFrequency: 97.3%High Priority

Number of Islands

Asked at TikTok

#14

Rank

#408EasyFrequency: 96.8%High Priority

Valid Word Abbreviation

Two Pointers String

#15

Rank

#364MediumFrequency: 95.4%High Priority

Nested List Weight Sum II

Stack Depth-First Search Breadth-First Search

#16

Rank

#269HardFrequency: 95.2%High Priority

Alien Dictionary

Array String Depth-First Search Breadth-First Search Graph Theory+2 more

#17

Rank

#680EasyFrequency: 95.1%High Priority

Valid Palindrome II

Two Pointers String Greedy

#18

Rank

#1306EasyFrequency: 94.7%High Priority

Minimum Absolute Difference

Array Sorting

#19

Rank

#1549MediumFrequency: 94.4%High Priority

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

Array Queue Sliding Window Heap (Priority Queue)Ordered Set+1 more

#20

Rank

#432HardFrequency: 93.8%High Priority

All O`one Data Structure

#21

Rank

#348MediumFrequency: 93.6%High Priority

Design Tic-Tac-Toe

Array Hash Table Design Matrix Simulation

#22

Rank

#314MediumFrequency: 93.4%High Priority

Binary Tree Vertical Order Traversal

Hash Table Tree Depth-First Search Breadth-First Search Sorting+1 more

#23

Rank

#215MediumFrequency: 93.3%High Priority

Kth Largest Element in an Array

Array Divide and Conquer Sorting Heap (Priority Queue)Quickselect

#24

Rank

#1352HardFrequency: 93%High Priority

Maximum Profit in Job Scheduling

Array Binary Search Dynamic Programming Sorting

#25

Rank

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Array (14)String (7)Breadth-First Search (7)Hash Table (6)Design (5)Depth-First Search (5)Matrix (4)Sorting (4)

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Quick Interview Prep - 25 Essential Problems

Curated list of 25 must-know problems for last-minute interview preparation.

Total Problems

Easy

Medium

Hard

97%

Avg Frequency

Most Common Topics

Companies Asking These Questions

Meta (5)Uber (3)LinkedIn (3)Databricks (3)Airbnb (2)Flipkart (2)

Problems in This Collection

#1EasyFrequency: 100%High Priority

Two Sum

Asked at Google

Array Hash Table

Rank

#1371MediumFrequency: 100%High Priority

Minimum Remove to Make Valid Parentheses

String Stack

Rank

#146MediumFrequency: 100%High Priority

LRU Cache

Asked at Apple

Rank

#833HardFrequency: 100%High Priority

Bus Routes

Array Hash Table Breadth-First Search

Rank

#716HardFrequency: 100%High Priority

Max Stack

Linked List Stack Design Doubly-Linked List Ordered Set

Rank

#2710MediumFrequency: 100%High Priority

Minimum Operations to Reduce an Integer to 0

Asked at Salesforce

Dynamic Programming Greedy Bit Manipulation

Rank

#286MediumFrequency: 100%High Priority

Walls and Gates

Asked at DoorDash

Array Breadth-First Search Matrix

Rank

#68HardFrequency: 100%High Priority

Text Justification

Array String Simulation

Rank

#1538MediumFrequency: 100%High Priority

Maximum Points You Can Obtain from Cards

Array Sliding Window Prefix Sum

Rank

#750HardFrequency: 100%High Priority

Contain Virus

Array Depth-First Search Breadth-First Search Matrix Simulation

#10

Rank

#6MediumFrequency: 100%High Priority

Zigzag Conversion

String

#11

Rank

#362MediumFrequency: 100%High Priority

Design Hit Counter

Array Binary Search Design Queue Data Stream

#12

Rank

#752MediumFrequency: 97.6%High Priority

IP to CIDR

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

String Bit Manipulation

#13

Rank

#200MediumFrequency: 97.3%High Priority

Number of Islands

Asked at TikTok

#14

Rank

#408EasyFrequency: 96.8%High Priority

Valid Word Abbreviation

Two Pointers String

#15

Rank

#364MediumFrequency: 95.4%High Priority

Nested List Weight Sum II

Stack Depth-First Search Breadth-First Search

#16

Rank

#269HardFrequency: 95.2%High Priority

Alien Dictionary

Array String Depth-First Search Breadth-First Search Graph Theory+2 more

#17

Rank

#680EasyFrequency: 95.1%High Priority

Valid Palindrome II

Two Pointers String Greedy

#18

Rank

#1306EasyFrequency: 94.7%High Priority

Minimum Absolute Difference

Array Sorting

#19

Rank

#1549MediumFrequency: 94.4%High Priority

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

Array Queue Sliding Window Heap (Priority Queue)Ordered Set+1 more

#20

Rank

#432HardFrequency: 93.8%High Priority

All O`one Data Structure

#21

Rank

#348MediumFrequency: 93.6%High Priority

Design Tic-Tac-Toe

Array Hash Table Design Matrix Simulation

#22

Rank

#314MediumFrequency: 93.4%High Priority

Binary Tree Vertical Order Traversal

Hash Table Tree Depth-First Search Breadth-First Search Sorting+1 more

#23

Rank

#215MediumFrequency: 93.3%High Priority

Kth Largest Element in an Array

Array Divide and Conquer Sorting Heap (Priority Queue)Quickselect

#24

Rank

#1352HardFrequency: 93%High Priority

Maximum Profit in Job Scheduling

Array Binary Search Dynamic Programming Sorting

#25

Rank

Other Collections

Most Frequent Interview Questions

The top 50 most frequently asked coding interview questions across all major tech companies.

Beginner-Friendly Interview Questions

Easy to medium difficulty problems perfect for interview preparation beginners.

75 problems →

Advanced Interview Problems

Challenging hard problems asked at top-tier tech companies for senior positions.