Object-Oriented Design of an Elevator Control System
Company: Tradedesk
Role: Frontend Engineer
Category: Software Engineering Fundamentals
Difficulty: medium
Interview Round: Onsite
Overview: An object-oriented design question asking the candidate to model an elevator control system: its classes, their responsibilities, and how a button press becomes an elevator stop. It tests requirement scoping, a clear per-car state model, stop ordering and dispatch policies that can be swapped out, handling of out-of-service cars and duplicate requests, and testability.