Online Judge (LeetCode)
Difficulty: Medium
What It Tests
Code execution sandbox, job queuing, result storage.
Topics Covered
- Message Queues & Async Processing
- Job Scheduling & Background Processing
- Database Design: SQL vs NoSQL
- API Design
- Blob / Object Storage
Hello Interview Breakdown
Read the full Hello Interview breakdown →
Approach Hints
- Sandboxed execution in Docker containers (nsjail/gVisor)
- Submit code to a job queue (Kafka/SQS), workers pull jobs and execute with resource limits (CPU/memory/time)
- Store results and submission history in a relational DB
- Return real-time execution status via polling or WebSocket