Low-level design

Standard

  • Design a game of chess.
    • Follow up:
      • How to implement rules of how different pieces move?
      • How to know if a piece can move from loc1 to loc2? how does the move happen?
      • How do you know there’s a checkmate?
      • Where to keep direction?
  • Counter Strike.
    • Requirements:
      • Two teams, cops and terrorists, each with some players.
      • Players can have weapons.
      • Players have a health counter, which goes down based on certain parameters (where was he hit, by what location/weapon etc.).
      • Assume 2D/grid-like maps. In future, we can add new maps.
    • Follow up:
      • How does a player know who all he can shoot?
      • How do you shoot (as in, what classes interact and how)?
      • How does player move?
  • Calendar, with ability to add events, get events for a given day and get details for a given event ID.

Simple

  • 2-player snakes and ladder.

High level design

Standard

  • A health monitoring system for a huge fleet of machines, with automated alerts and admin UI.
    • Follow up:
      • Pull vs push?
      • Where do you keep thresholds on when to alarm? Can you ensure separate thresholds for same metrics for different people?
      • APIs
      • How do you add more metrics in future?
      • How do you know your system is working fine?
  • Netflix: based on certain rules, that should be extendable, should user be allowed to watch a title? For e.g., geography, membership type, HD or not etc.

Simple

  • A service to ingest and vend out logs, something similar to Timber.
    • Requirements:
      • Dedupe data based on something.
      • Don’t look inside the logs. Ingest as is.
      • APIs.
      • Advanced- design the daemon which is doing log rotation on hosts.
  • Wish list feature on amazon.
    • Follow up:
      • How is watchlist stored in backend? RDBMS or NoSQSL?
      • How would you run into concurrency problems in distributed systems?

Upcoming

  • A system to match competitor prices.
  • Dacia (only if candidate has worked on sqs or other queueing system before)?
  • Meeting room booking system.
  • Distributed throttling between a group of machines
  • IRCTC website?
    • Requirements:
  • DJS?
  • Top 10 trending products.

High and low level design together

Standard

  • Bar exchange where prices go up or down depending on demand.
    • Requirements:
      • Multiple tables.
      • Users can order multiple times.
      • They should pay the price of item when they ordered.
      • Decider can be assumed as a black box but think about its input and output data.
    • Follow up:
      • How will this work for multiple restaurants?
      • Inventory validation? Can you blindly take an order and deny later? How do clients know if item is still available?
      • Can decider be notified of incoming orders?
      • Do you take price as input from clients (which can be rogue) or store in your system?
  • System to reserve tables in a restaurant.
    • Requirements:
      • For one restaurant, book tables for requested time range and capacity.
      • All components, such as mobile app with restaurant host, backend, etc.
    • Follow up:
      • Database modeling.
      • Merge tables.
      • How to extend system to bar stools?
      • Advanced- how to extend to multiple restaurants?

Upcoming

  • Public library, which has lot of branches, allows placing a hold, etc.