Implement and Test a Sliding-Window Rate Limiter
Company: Snowflake
Role: Software Engineer
Category: Software Engineering Fundamentals
Difficulty: medium
Interview Round: Onsite
Overview: Design an in-memory limiter with `allow(key, timestamp)` for a configurable maximum number of requests in the preceding window. Make the API or object boundaries explicit, then cover invariants, edge cases, testing strategy, and operational trade-offs.