Design coding platform with global leaderboard

Scenario

Design a LeetCode-like online coding practice platform that also has a global leaderboard (e.g., Top K users by score) and can show a user’s rank.

Functional requirements

• Users can:
  • Browse problems.
  • Submit code for a problem in a chosen language.
  • Receive verdicts (Accepted/Wrong Answer/Time Limit, etc.) and runtime/memory stats.
• The system maintains a leaderboard :
  • Score model is flexible (e.g., points per solved problem, bonus for difficulty, penalties for wrong submissions).
  • Support queries:
    • GetTopK(k) (global and optionally per region/time window).
    • GetUserRank(userId) .

Non-functional requirements

• High throughput during peaks (many submissions at once).
• Low-latency reads for Top K leaderboard.
• Correctness and anti-cheat considerations.
• Observability: be able to identify bottlenecks and scale the right components.

Deliverables

1. High-level architecture and main services.
2. Data model (what is stored where).
3. APIs for submission + leaderboard queries.
4. How leaderboard updates are computed and served efficiently.
5. Identify likely bottlenecks and how you’d improve them.