Create a system for managing a parking lot.

This inquiry focuses on the design of a system, specifically a parking lot system. The interviewer aims to gauge how you apply your technical expertise and problem-solving abilities to real-world challenges. To deliver a comprehensive explanation, start by outlining the system's requirements, functionalities, and limitations. After that, move on to a high-level design before exploring the specifics, making sure to highlight key decisions and trade-offs throughout the process. Consider the following aspects: Types of Vehicles : Is the parking facility intended for a specific type of vehicle or for all vehicle types? The design will differ significantly depending on whether it's meant for cars, bicycles, trucks, or a combination of them. Parking Lot Size or Capacity : This will inform the types of data structures and algorithms you might require. Entry and Exit Points : These will affect traffic management within the parking area. Payment System : Is it a pay-and-park setup, and if so, what are the methods for calculating and collecting payments?

A fundamental design for this system could involve creating a ParkingLot class that maintains a list of ParkingSpot objects, each of which may be occupied by a Vehicle object. The ParkingLot class would also include methods for parking a vehicle ( parkVehicle ), removing a vehicle ( removeVehicle ), and checking for available space ( hasSpace ). The Vehicle class should contain properties such as plateNumber , VehicleType , and TimeOfEntry . The VehicleType can be represented as an Enum that defines the types of vehicles that can be parked. Additionally, the ParkingSpot class will feature fields like spotNumber , floorNumber , isOccupied , and Vehicle . In this design, the parking spots are stored in a data structure such as a priority queue. This enables the system to efficiently locate the nearest available spot to the entrance of the parking lot when a vehicle wishes to park.

Let's examine a multi-level parking facility. We can begin by establishing classes for Level , Slot , and Vehicle . The Slot class may include properties such as slotNumber , isOccupied , and Vehicle . The Vehicle class should encompass attributes like vehicleType , licensePlate , timeOfEntry , and so forth. The Level class consists of a collection of slots. It features methods to check if there are available slots ( hasAvailableSlot ), locate the nearest free slot ( getAvailableSlot ), park a vehicle ( parkVehicle ), and remove a vehicle ( removeVehicle ). Additionally, we require a ParkingLot class that contains a list of Level instances. Moreover, to oversee payments, we can introduce a Payment class responsible for fee calculations and processing payments. This class might include methods like calculateFee and makePayment . The parking lot system also features Entrance and Exit classes that interact with the ParkingLot to park or remove vehicles, as well as to process charges through the Payment class. This design facilitates easy expansion of the parking facility both horizontally (adding more slots on a level) and vertically (adding more levels). It also delineates responsibilities, with each class managing a specific aspect of the overall functionality.