Quick Interview Prep - 25 Essential Problems

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

25

Total Problems

4

Easy

17

Medium

4

Hard

98%

Avg Frequency

Most Common Topics

Array (14)Hash Table (10)String (8)Sorting (8)Breadth-First Search (5)Design (5)Two Pointers (5)Heap (Priority Queue) (4)

Companies Asking These Questions

Meta (5)Oracle (3)Microsoft (2)Uber (2)Salesforce (2)DoorDash (2)

Problems in This Collection

#1EasyFrequency: 100%High Priority

Two Sum

Asked at Google

Array Hash Table

#1

Rank

#3594MediumFrequency: 100%High Priority

Identify the Largest Outlier in an Array

Asked at Amazon

Array Hash Table Counting Enumeration

#2

Rank

#3655MediumFrequency: 100%High Priority

Digit Operations to Make Two Integers Equal

Asked at Microsoft

Math Graph Heap (Priority Queue)Number Theory Shortest Path

#3

Rank

#1371MediumFrequency: 100%High Priority

Minimum Remove to Make Valid Parentheses

#4

Rank

#3638HardFrequency: 100%High Priority

Minimum Operations to Make Character Frequencies Equal

Asked at TikTok

Hash Table String Dynamic Programming Counting Enumeration

#5

Rank

#3613MediumFrequency: 100%High Priority

Maximize Amount After Two Days of Conversions

Array String Depth-First Search Breadth-First Search Graph

#6

Rank

#716HardFrequency: 100%High Priority

Max Stack

Asked at LinkedIn

Linked List Stack Design Doubly-Linked List Ordered Set

#7

Rank

#49MediumFrequency: 100%High Priority

Group Anagrams

Asked at Oracle

Array Hash Table String Sorting

#8

Rank

#71MediumFrequency: 100%High Priority

Simplify Path

Asked at Oracle

#9

Rank

#1306EasyFrequency: 100%High Priority

Minimum Absolute Difference

Asked at Oracle

#10

Rank

#532MediumFrequency: 100%High Priority

K-diff Pairs in an Array

Asked at Salesforce

Array Hash Table Two Pointers Binary Search Sorting

#11

Rank

#1423MediumFrequency: 100%High Priority

Maximum Number of Occurrences of a Substring

Asked at Salesforce

Hash Table String Sliding Window

#12

Rank

#286MediumFrequency: 100%High Priority

Walls and Gates

Asked at DoorDash

Array Breadth-First Search Matrix

#13

Rank

#1171MediumFrequency: 100%High Priority

Shortest Path in Binary Matrix

Asked at Airbnb

Array Breadth-First Search Matrix

#14

Rank

#146MediumFrequency: 100%High Priority

LRU Cache

Asked at Flipkart

Hash Table Linked List Design Doubly-Linked List

#15

Rank

#295HardFrequency: 100%High Priority

Find Median from Data Stream

Asked at PayPal

Two Pointers Design Sorting Heap (Priority Queue)Data Stream

#16

Rank

#362MediumFrequency: 100%High Priority

Design Hit Counter

Asked at Databricks

Array Binary Search Design Queue Data Stream

#17

Rank

#314MediumFrequency: 97%High Priority

Binary Tree Vertical Order Traversal

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

#18

Rank

#227MediumFrequency: 96%High Priority

Basic Calculator II

Math String Stack

#19

Rank

#658MediumFrequency: 96%High Priority

Find K Closest Elements

Asked at DoorDash

Array Two Pointers Binary Search Sliding Window Sorting+1 more

#20

Rank

#680EasyFrequency: 95%High Priority

Valid Palindrome II

Two Pointers String Greedy

#21

Rank

#833HardFrequency: 95%High Priority

Bus Routes

Array Hash Table Breadth-First Search

#22

Rank

#348MediumFrequency: 93%High Priority

Design Tic-Tac-Toe

Asked at Databricks

Array Hash Table Design Matrix Simulation

#23

Rank

#88EasyFrequency: 92%High Priority

Merge Sorted Array

Asked at Microsoft

Array Two Pointers Sorting

#24

Rank

#215MediumFrequency: 92%High Priority

Kth Largest Element in an Array

Array Divide and Conquer Sorting Heap (Priority Queue)Quickselect

#25

Rank

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