Simulate Constant-Time Random Courier Selection
Company: DoorDash
Role: Software Engineer
Category: Coding & Algorithms
Difficulty: medium
Interview Round: Technical Screen
Overview: Maintain a changing set of courier IDs with expected constant-time add, remove, and deterministic random-pick operations. The challenge probes coordinated array and index-map state, swap-based removal correctness, concurrency boundaries, external-call isolation, and distributed extensions.
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