Track the Contiguous Package Frontier and Missing IDs
Company: Amazon
Role: Software Engineer
Category: Coding & Algorithms
Difficulty: medium
Interview Round: Technical Screen
Overview: Design a PackageTracker that handles out-of-order and duplicate package IDs while maintaining the contiguous delivered frontier from zero. Discuss how to report every missing ID up to the largest observed package, analyze amortized update and output-sensitive reporting costs, and scale the API for extremely sparse ranges.
