Interview questions

Plan Round Trip With Minimum Flight Cost

Plan a round trip between 2 cities with minimum flight cost, given departure and return cost arrays.

Companies: Meta

Last reported Jul 2026

Matrix Diagonal Sum

Compute the sum of the primary and secondary diagonals of an n×n matrix, making sure to count the center element only once when n is…

Companies: Amazon

Last reported Jul 2026

Find Lowest Value in Array

Given an array of integers, return the smallest value in the array. Do not use built-in min/max functions.

Companies: Merge

Last reported Jul 2026

Design Memory Allocator

Design an allocator for n memory units that supports allocating the leftmost contiguous block of a given size and freeing all units with a given…

Companies: Apple, OpenAI, Roblox

Array · Design · Hash Table · Simulation

Last reported Jul 2026

First Column Starting With 'A'

Given a 2D matrix or dataset, identify and return all values from the first column where the entry starts with the letter 'A'. Handle edge…

Companies: Uber

Last reported Jul 2026

Smallest Greater Number from Digits

Given a list of digits and a lower bound string of equal length, construct the smallest possible number from those digits that is greater than…

Companies: Airbnb

Last reported Jul 2026

Change Directory

Implement a function that simulates the 'cd' (change directory) command, handling both relative and absolute paths. Handle edge cases such as invalid paths and proper…

Companies: Meta

Last reported Jul 2026

Cursor-Based Pagination

Implement a cursor-based pagination system in TypeScript. The solution should handle efficient data traversal and retrieval using cursor pointers rather than traditional…

Companies: Hex

Last reported Jul 2026

Design File System

Implement an in-memory hierarchical file system that supports createPath(path, value) — which should succeed only if the immediate parent path exists and the path is…

Companies: Anchorage Digital, Capital One, Google, Uber

Last reported Jul 2026

Determine if a String is a Palindrome

Given a string, determine whether it reads the same forwards and backwards. Return true if the string is a palindrome, false otherwise.

Companies: Meta

Last reported Jul 2026

Find First and Last Position of Element in Sorted Array

Given a sorted (non-decreasing) array, return the starting and ending indices of a target value (or [-1, -1] if it’s not present). The challenge is…

Companies: Amazon, Apple, Meta, NVIDIA +3

Array · Binary Search

Last reported Jul 2026

Notebook React Component with Shared State

Build a Notebook React component using the provided scaffolding repository where multiple components share and sync data via a subscription-based API. Components should…

Companies: Hex

Last reported Jul 2026

Promotion Rule Engine

Given a JSON input containing a user's cart context and a list of promotion rules with conditions (e.g., EQUAL, GREATER_THAN), evaluate which promotions apply and…

Companies: Coupang

Last reported Jul 2026

Build a Progressive Banking Ledger

Implement a banking account system through four stages of increasing complexity. Preserve earlier behavior as each stage adds requirements.

Companies: Airbnb, Anthropic

CodeSignal · Data Structure Design · Incremental Implementation · Progressive Assessment

Last reported Jul 2026

Build a Progressive Cloud Storage System

Implement a file store that grows from basic file operations to search and user capacity limits. Practice one final extension at a time: compression or…

Companies: Airbnb, Anthropic

CodeSignal · File & Media Storage · Low-Level Design (OOP) · Progressive Assessment

Last reported Jul 2026

Build a Progressive Employee Tracker

Companies: Anthropic

Data Structure Design · Simulation & State Machines

Last reported Jul 2026

Build a Versioned In-Memory Database

Implement an in-memory database with fields, filtered reads, and values that expire. Then practice a named final extension: historical lookup or backup and restore.

Companies: Anthropic, eBay

CodeSignal · Data Structure Design · Progressive Assessment · State Machines

Last reported Jul 2026

Calculate How Much XRP a Customer Can Buy with a Given USD Budget

Write a function that calculates how much XRP a customer can buy with a given USD budget. Return the total amount of XRP the customer…

Companies: Ripple

Last reported Jul 2026

Calculate Streaming Token Usage Costs

Companies: Anthropic

Arrays & Strings

Last reported Jul 2026

Convert Stack Samples into Trace Events

Companies: Anthropic

Arrays & Strings · Simulation & State Machines · Stacks & Queues

Last reported Jul 2026

Implement a Longest-Match Tokenizer

Companies: Anthropic

Parsing & Interpreters · String Algorithms

Last reported Jul 2026

Merge Request Code Review

Review a ~70-line merge request of varying complexity and decide whether you would approve it. Identify both obvious and subtle issues that should be addressed…

Companies: Datadog, JPMorgan Chase

Last reported Jul 2026