Microsoft SDE-1 off-campus — Tic-Tac-Toe LLD and a URL shortener

Background

I applied directly through the Microsoft careers portal using a referral from a senior contact.

Resume shortlisting

My internship experience at a couple of well-known tech companies seemed to carry real weight at this stage.

Online assessment

Coding problems around two medium and one hard. To clear it I needed to solve them completely rather than partially.

Round-by-round

(All three rounds on the same day, roughly 45 minutes each.)

Technical round 1 — Low-level design

Design a simple two-player grid-based game (think Tic-Tac-Toe): class structure, relationships, and how game state would be managed. The follow-up was to extend it with logic for the optimal move at any state, which meant a game-tree-based decision algorithm.

There was also a coding question on rotating a 2D matrix — in place, modifying the original rather than creating a new one.

Technical round 2 — System design

Designing a large-scale URL-shortening service: how the mapping between short and long URLs works, handling billions of unique addresses, what hashing strategy makes sense, and edge cases at that scale.

Managerial round

Technical and behavioural. On the technical side, networking fundamentals — DNS, HTTP, the three-way handshake, TLS/SSL. On the behavioural side, academic background and internships in more depth.

Verdict

Selected.