Design a Tiered Expiring Item Store
Company: Akuna Capital
Role: Software Engineer
Category: Software Engineering Fundamentals
Difficulty: hard
Interview Round: Technical Screen
Overview: Design a tiered in-memory item store that places weighted items under capacity limits and retrieves from the highest-priority eligible level while respecting expiration. The solution covers deterministic tie-breaking, dual heaps with lazy cleanup, exact capacity accounting, concurrency, and tests around the 50% free-capacity boundary.