Interview prep

Coding and system design questions I've seen or asked, each with a worked solution, the trade-offs, and what interviewers usually look for.

Two Sum
Coding easy

Find two numbers in an array that add up to a target. A classic warm-up that tests whether you reach for a hash map.
22 Oct 2026
Design a URL shortener
System design medium

Design a service like bit.ly. A great first system design question covering IDs, storage, caching and scale.
21 Oct 2026