Interview questions

Parallel Courses

Given n courses and prerequisite pairs, determine the minimum number of semesters required to finish all courses if you can take any number of courses…

Companies: Snowflake

Last reported Sep 2026

Product of Array Except Self

For each index in an integer array, compute the product of all other elements without using division and in O(n) time — typically done by…

Companies: Amazon, Asana, Meta, Snap

Array · Prefix Sum

Last reported Sep 2026

Ransom Note

Determine whether ransomNote can be formed from magazine by verifying that for every character, magazine contains at least as many occurrences as needed — i.e.…

Companies: Anduril, Pinterest

Counting · Hash Table · String

Last reported Sep 2026

Shortest Path in a 2D Grid with Obstacles (with Path Reconstruction)

Given a 2D grid of a specified size, start coordinates, and end coordinates, find the shortest path between the two points. The problem is presented…

Companies: Amazon, Anduril

Last reported Sep 2026

Simple Bank System

Design a Bank class that maintains 1-indexed account balances and supports transfer, deposit, and withdraw operations; each operation must validate account indices and (for…

Companies: Capital One, Coinbase, Okta, OpenAI +1

Last reported Sep 2026

Snake Game Implementation

Design a Snake game class with a 40x30 screen, wrapping boundaries, automatic growth every 5 moves, and collision detection for game over conditions.

Companies: Atlassian, Watershed

Last reported Sep 2026

Snapshot Array

Design a versioned array that supports point updates, taking snapshots (returning increasing snap_ids), and querying the value at an index for a given snap_id. The…

Companies: Amazon, Anduril, Apple, Google DeepMind +1

Array · Binary Search · Design · Hash Table

Last reported Sep 2026

Stuff My Friends Bought

Given two APIs to retrieve a person's purchases and friends, implement a function that returns all items purchased by a user's friends (excluding items the…

Companies: Amazon

Last reported Sep 2026

URL Query String Parser

Parse a URL query string into a key-value map, where values can be a boolean (for keys with no value), a string, or a list…

Companies: Airbnb

Last reported Sep 2026

Alien Dictionary

Given a sorted list of words in an unknown alphabet, infer the relative ordering of characters by deriving precedence constraints between first differing letters, then…

Companies: Amazon, Bloomberg, Google, Intuit +3

Array · Breadth-First Search · Depth-First Search · Directed Acyclic Graph

Last reported Aug 2026

Burst Balloons

Given an array of balloon values, find the maximum coins you can collect by bursting balloons optimally. When you burst balloon at index i, you…

Companies: Amazon, Apple, Google

Last reported Aug 2026

Candy

Given a line of children with integer ratings, assign each at least one candy so any child with a higher rating than a neighbor gets…

Companies: LinkedIn, Marvin, PayPal

Last reported Aug 2026

Car Rental Optimization

Given N cars and a list of rental requests (each with pickup time, return time, and ID), assign cars to requests using the minimum number…

Companies: Amazon, Google, Waymo

Last reported Aug 2026

Design a Data Structure with Insert, Remove, and GetRandom for Unique Elements in O(1)

Design a data structure that supports three operations, all in average O(1) time: - insert(val): adds val to the data structure if not already present…

Companies: Nebuis

Last reported Aug 2026

Design a Package Tracking System with Courier Assignment, Event Recording, Undo, and Sign-Out

Implement a multi-level package tracking system supporting: recording parcel events under an assigned courier (RecordCourierEvent), querying total event counts per courier…

Companies: Airbnb

Last reported Aug 2026

Diagonal Traverse II

Return the elements of a possibly jagged 2D array in diagonal (anti-diagonal) order, where cells on the same diagonal share the same i+j value and…

Companies: Meta

Last reported Aug 2026

Edit Distance

Compute the minimum number of single-character insertions, deletions, or replacements needed to transform word1 into word2 (the classic Levenshtein edit distance), typically…

Companies: Amazon, LinkedIn

Last reported Aug 2026

Find the Left and Right Side View of a Binary Search Tree

Given a binary search tree, return the left side view from bottom to top, and the right side view from top to bottom. Ensure there…

Companies: Meta

Last reported Aug 2026

Furthest Building You Can Reach

Given an array of building heights and limited bricks and ladders, find the furthest building index you can reach from 0 by covering each positive…

Companies: D. E. Shaw, SchröDinger

Array · Greedy · Heap (Priority Queue)

Last reported Aug 2026

Group Shifted Strings

Group strings that are equivalent under a uniform alphabetical shift (e.g., "abc" → "bcd", with wrap-around) by identifying a shift-invariant signature for each string and…

Companies: Google, Meta

Last reported Aug 2026

IP to CIDR

Given a start IPv4 address and a number of consecutive addresses, produce the minimal list of CIDR blocks that exactly cover that range. The key…

Companies: Databricks

Bit Manipulation · String

Last reported Aug 2026

Letter Combinations of a Phone Number

Given a string of digits 2–9, return all possible letter strings by mapping each digit to its phone-keypad letters — effectively computing the Cartesian product…

Companies: Amazon, Google, LinkedIn, Microsoft +1

Backtracking · Hash Table · String

Last reported Aug 2026