Hard

Design a Multi-Elevator Dispatch System Object-Oriented Design Interview

Design a controller for multiple elevators that accepts hall and cabin requests, schedules cars, models movement and doors safely, and supports replaceable dispatch policies.

Mock Interview with AI

1. Problem Statement

Design a multi-elevator system that handles hall calls and cabin floor selections, dispatches requests to appropriate cars, and models movement, stops, and door operation safely.

2. Live Coding Format

Work in the provided coding workspace while explaining your decisions to the live interviewer. Validation may use inline tests, examples, comments, or a verbal walkthrough.

3. Key Focus Areas

1
Hall-call versus cabin-request modeling
2
Elevator car state machine and safety invariants
3
Multi-car dispatch strategy
4
Request ordering, fairness, and starvation

4. What Strong Candidates Should Demonstrate

✓Separate elevator-car state from building-wide dispatch coordination.
✓Model safe movement, door, and stop transitions explicitly.
✓Use a strategy boundary for scheduling and explain fairness trade-offs.
✓Validate multi-request behavior with a deterministic handwritten trace.

Want interactive feedback?

Practice this problem in the live coding workspace while the interviewer probes your clarification, implementation, trade-offs, and validation.

Start Interview

Core Concepts

Object-Oriented DesignState MachineScheduling Strategy