Requirements

Design a parking lot management system that supports multiple levels, multiple entry/exit gates, different vehicle types, and automated ticketing plus payment. The system should **allocate appropriate parking spots** based on vehicle type and real-time availability, **track occupancy**, and **calculate parking fees** when vehicles exit. --- # Requirements ### Functional Requirements * The system manages a parking lot with **one or more levels**, each containing multiple parking spots. * The system supports **multiple vehicle types** (e.g., motorcycle, car, bus/truck) and maps them to compatible **spot types** (motorcycle, compact, large). * When a vehicle enters through any **entry gate**, the system issues a **parking ticket** and assigns one or more valid spots. * The system records **entry time**, vehicle details, assigned spot(s), and gate information on the ticket. * When a vehicle leaves through any **exit gate**, the system **calculates the parking fee** based on duration and pricing rules, **processes payment**, and closes the ticket. * The system updates **spot status** (occupied/free) and maintains real-time **availability** per level and per spot type. * Parking attendants or admins can **query current occupancy**, view historical ticket/payment data, and **enable/disable spots or levels** for maintenance. ### Non-Functional Requirements * **Scalability**: Support large parking facilities (thousands of spots, many gates) without noticeable degradation in gate processing time. * **Performance**: Entry and exit operations (spot assignment, ticket lookup, fee calculation) should complete within a few hundred milliseconds to avoid long queues. * **Concurrency**: Safely handle concurrent entries and exits from multiple gates, ensuring that no two vehicles are assigned the same spot at the same time. * **Availability & Reliability**: High availability during operating hours and durable storage of tickets, payments, and audit logs. * **Maintainability & Extensibility**: The design should allow easy addition of new vehicle types, pricing policies, reservations, or EV charging spots. * **Security**: Protect vehicle, user, and payment information; restrict configuration changes (pricing, capacity, maintenance) to authorized personnel. --- ## Core Entities * **ParkingLot**: Represents the entire parking facility. * **Level**: Represents a floor within the parking lot. * **ParkingSpot**: Represents a single parking space. * **Vehicle**: Represents a vehicle entering the lot. * **Ticket**: Represents a parking session. * **Gate**: Represents a physical gate. * **PricingPolicy**: Represents pricing rules. * **Payment**: Represents payment for a ticket.

Design Parking Lot.

Requirements

Interview Simulation

Functional Requirements

💡 Interview Tip

Non-Functional Requirements

Core Entity Identification