Explain HashMap Resizing Without Long Pauses
Company: Apple
Role: Software Engineer
Category: Software Engineering Fundamentals
Difficulty: medium
Interview Round: Technical Screen
Explain how a hash map works internally. Cover how keys are mapped to buckets, how collisions are handled, and when the table decides to resize.
Follow-up: resizing usually requires allocating a larger bucket array and moving existing entries into it, which can create a noticeable latency spike. Design an approach to cap or smooth that latency while preserving expected constant-time lookups and inserts.
Overview: This question evaluates understanding of hash map internals—how keys are mapped to buckets, collision resolution strategies, and when and why resizing occurs—testing competence in data structures and performance engineering within the Software Engineering Fundamentals domain.