I started with the class hierarchy and got a bit too deep into vehicle subclasses before touching the spot assignment logic, which I think was the wrong order.
Start by clarifying requirements and scope, then define core entities and their relationships using OOP principles. Walk through key use cases like vehicle entry/exit and payment, and discuss concurrency and scalability trade-offs.
Pro tip: Emphasize separation of concerns and extensibility—show how your design can easily accommodate new vehicle types or pricing models without major refactoring. Also, proactively mention concurrency control mechanisms like optimistic locking or distributed locks, as this is critical for a high-scale system like Uber's.
Ask questions to understand functional and non-functional requirements, such as expected scale, vehicle types, payment methods, and concurrency needs. This ensures your design addresses the right problems.
Define classes like ParkingGarage, Level, ParkingSpot, Vehicle, Ticket, Payment, and their associations. Use inheritance for vehicle types and spot types to promote extensibility.
Walk through entry (assign spot, generate ticket), exit (calculate fee, process payment), and availability queries. Show how objects interact via methods and services.
Discuss how to handle concurrent access to spots and tickets, using techniques like locking, atomic operations, or distributed coordination. Consider partitioning by level or spot type.
Highlight design trade-offs (e.g., inheritance vs. composition, centralized vs. distributed locking) and how to extend for new features like EV charging or dynamic pricing.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.