System Design: 100 Interview Questions by X.Y. Wang — Review

System design interviews (SDI) have become the most-discussed round for senior engineer hiring at FAANG-tier companies. Alex Xu's System Design Interview Volume 1 & 2 dominate the prep literature. X.Y. Wang's 100 Questions book tries to complement that by offering breadth — 100 problems vs Xu's 20-30 deep-dives.

What The Book Offers

100 system design problems grouped by theme:

• Distributed systems fundamentals (CAP, consensus, consistency)
• Data storage (SQL vs NoSQL choice, sharding, replication)
• Message queues and streaming (Kafka, SQS, Kinesis-style)
• Caching (Redis patterns, cache invalidation, consistent hashing)
• Load balancing and service discovery
• Scaling specific services (URL shortener, rate limiter, search, chat, video streaming)
• Storage-heavy services (Dropbox-style, Google Drive)
• Geographic services (Uber, Yelp, Google Maps)

Each question gets a 2-5 page treatment: requirements clarification, high-level architecture sketch, key components discussion, trade-offs.

vs Alex Xu's Books

Xu: 20-30 problems with 15-30 pages each. Deep trade-off discussion. Illustrated architecture diagrams. Widely cited as the SDI reference.

Wang: 100 problems with 2-5 pages each. Broader coverage, less depth per problem. Works better as a quick-reference than a teaching book.

Recommended sequence: Xu first for depth, Wang second for breadth.

Strongest Aspects

Problem variety. Xu covers the popular problems (URL shortener, chat, news feed). Wang covers these plus 70+ less-common scenarios (stock trading system, vaccine distribution, dating app matching, multi-region leaderboard). If your interviewer asks a less-common problem, Wang is more likely to have touched it.

Quick-reference format. The brevity helps in the final week of prep. You can skim 10-15 problems per hour.

Weaknesses

Depth per problem. 2-5 pages is not enough to really teach a complex system. If you don't already have the distributed systems fundamentals, Wang's treatment is too terse.

Illustration quality. Wang's diagrams are simpler than Xu's. Visual learners may find the Xu books easier.

Currency. Both books target 2019-2022 industry practice. Modern patterns (vector databases, stream-first architectures, serverless primitives) get light treatment.

How To Use It

1. Read Alex Xu Volume 1 first. Learn the vocabulary, the canonical problems, the thinking framework.
2. Read Wang for breadth. Skim 5-10 problems per session. Focus on less-common problems.
3. Practice whiteboarding. Neither book replaces actual practice. Do mock interviews.

Who Should Read

Senior engineers prepping for system design interviews. Current ICs who want to strengthen their architecture intuition.

Who Should Skip

Junior engineers (start with fundamentals first — DDIA, Xu). Anyone who hasn't built distributed systems in practice — the book assumes working intuition.

Verdict

A useful breadth-oriented complement to Alex Xu's books. Not a standalone SDI resource. Use as your final week's quick-reference prep.