SDE-2 at Microsoft

How it went

What they would tell you

How to prepare

Their background

Round by round

1. 1

   Data Structures & Algorithms (DSA)60 min

   Start with intro part, then just basic resume mentioned questions then some core java language Problem1: Find LCA of two given nodes in a binary tree Problem2: Given an unsorted array of integers, find the length of the longest consecutive elements sequence.

   • Lowest Common Ancestor of a Binary Tree IV
   • Longest Consecutive Sequence
2. 2

   Low-Level Design60 min

   Problem: Design Parking Lot.

3. 3

   Design60 min

   Design a Rate-Limited Distributed API Gateway Problem:

   • Implement an API Gateway that exposes multiple APIs to clients.

   • Requirements:

   • Each API has a rate limit per user (e.g 100 requests per minute).

   • Support dynamic updates of rate limits without restarting the gateway.

   • Must handle concurrent requests from multiple clients efficiently.

   • Support burst handling: allow short spikes without dropping all requests.

   • Should return proper HTTP error codes when limits are exceeded. Follow-ups was related to scaling

   • How to distribute the rate limiter across multiple servers.

   • How to persist request counts in case of server crash.

   • How to optimize for latency while enforcing rate limits.

   • How to handle multi-tiered rate limits (per user, per API, per region).

What came up