Car Rental System
What is the Car Rental System Problem?
Section titled “What is the Car Rental System Problem?”Design a Car Rental System that manages a fleet of vehicles (cars, SUVs, trucks) with different states (Available, Rented, Maintenance, Retired). The system should support vehicle booking for specific date ranges, calculate rental costs based on vehicle type, duration, and location, check availability, handle pickup/dropoff at different locations, track vehicle damage, manage insurance options, and implement a loyalty program for customers.
In this problem, you’ll design a system that coordinates vehicle inventory, manages complex state transitions, implements flexible pricing strategies, and handles concurrent booking operations while maintaining data consistency.
Problem Overview
Section titled “Problem Overview”Design a comprehensive car rental system that manages vehicle inventory, handles bookings, calculates dynamic pricing, tracks vehicle conditions, and rewards loyal customers.
Core Requirements
Section titled “Core Requirements”Functional Requirements:
- Vehicle Management: Manage fleet of vehicles including cars, SUVs, and trucks, each with unique identifiers, make, model, and year.
- Vehicle States: Track vehicle states (Available, Rented, Maintenance, Retired) and handle state transitions based on operations.
- Rental Booking: Allow customers to book vehicles for specific start and end dates with automatic state transitions.
- Pricing: Calculate rental costs based on vehicle type, rental duration (daily/weekly/monthly), pickup/dropoff locations, and any applicable discounts.
- Availability Check: Check vehicle availability for given dates considering existing bookings and vehicle states.
- Pickup/Dropoff: Support pickup and dropoff at different locations with appropriate one-way fees.
- Damage Tracking: Track vehicle condition and damage reports, automatically transitioning damaged vehicles to Maintenance state.
- Insurance: Support multiple insurance options (Basic, Premium, Full Coverage) that can be added to bookings.
- Loyalty Program: Track customer loyalty points based on rental costs and apply discounts based on loyalty status.
Non-Functional Requirements:
- Object-Oriented Design: Clear separation of concerns with well-defined roles for each class.
- Modularity: Easy to add new vehicle types, pricing strategies, or insurance options without modifying existing code.
- Thread Safety: Booking operations, availability checks, and state transitions must be safe from race conditions.
- State Management: Robust vehicle state management preventing invalid state transitions.
- Reliability: Core rental logic should be robust, testable, and maintainable over time.
What’s Expected?
Section titled “What’s Expected?”1. System Architecture
Section titled “1. System Architecture”The system manages vehicles, bookings, customers, and locations through a centralized rental service.
2. Key Classes to Design
Section titled “2. Key Classes to Design”classDiagram
class RentalService {
-Map~String,Vehicle~ vehicles
-Map~String,Booking~ bookings
+searchAvailableVehicles()
+bookVehicle()
+returnVehicle()
}
class Vehicle {
-VehicleState currentState
-PricingStrategy pricingStrategy
+rent()
+returnVehicle()
+startMaintenance()
}
class VehicleState {
<<interface>>
+rentVehicle()
+returnVehicle()
}
class PricingStrategy {
<<interface>>
+calculatePrice()
}
RentalService --> Vehicle
RentalService --> Booking
Vehicle --> VehicleState
Vehicle --> PricingStrategy
Vehicle "1" -- "many" Booking
System Flow
Section titled “System Flow”Booking Flow (State Transitions)
Section titled “Booking Flow (State Transitions)”
Key Design Challenges
Section titled “Key Design Challenges”1. Managing Vehicle States
Section titled “1. Managing Vehicle States”Vehicles transition between Available, Rented, Maintenance, and Retired states based on various operations. Invalid transitions must be prevented.
Solution: Use the State Pattern. Create state classes (AvailableState, RentedState, MaintenanceState, RetiredState) that encapsulate state-specific behavior. Each state defines which transitions are valid, preventing invalid operations.
2. Flexible Pricing Strategies
Section titled “2. Flexible Pricing Strategies”Pricing should vary based on vehicle type, rental duration (daily vs weekly vs monthly), and location (premium locations cost more).
Solution: Use the Strategy Pattern. Create pricing strategy classes (DailyPricingStrategy, WeeklyPricingStrategy, MonthlyPricingStrategy) that encapsulate different pricing algorithms. Vehicles can use different strategies, and strategies can be swapped at runtime.
3. Creating Different Vehicle Types
Section titled “3. Creating Different Vehicle Types”The system needs to create cars, SUVs, and trucks without exposing the creation logic or requiring changes to existing code when new types are added.
Solution: Use the Factory Pattern. Create a VehicleFactory interface with a VehicleFactoryImpl that creates instances based on vehicle type. This decouples creation logic and makes adding new vehicle types easy.
4. Concurrent Booking Operations
Section titled “4. Concurrent Booking Operations”Multiple customers might try to book the same vehicle simultaneously, leading to double-booking.
Solution: Implement thread-safe operations using synchronized blocks/locks and concurrent collections. Availability checks and booking operations are atomic, preventing race conditions.
What You’ll Learn
Section titled “What You’ll Learn”By solving this problem, you’ll master:
- ✅ State Pattern - Managing complex lifecycles with clear state transitions.
- ✅ Strategy Pattern - Implementing flexible, swappable algorithms.
- ✅ Factory Pattern - Decoupling object creation from usage.
- ✅ Concurrency Control - Using locking mechanisms to prevent data corruption.
- ✅ System Design - Coordinating multiple entities (vehicles, bookings, customers) in a real-world scenario.
View Complete Solution & Practice
Section titled “View Complete Solution & Practice”Ready to see the full implementation? Open the interactive playground to access:
- 🎯 Step-by-step guidance through the 4-step LLD approach
- 📊 Interactive UML builder to visualize your design
- 💻 Complete Code Solutions in Python, Java, C++, TypeScript, JavaScript, C#
- 🤖 AI-powered review of your design and code
Related Problems
Section titled “Related Problems”After mastering the Car Rental System, try these similar problems:
- Parking Lot - Similar state management and resource allocation.
- Hotel Management System - Similar booking and availability management.
- Library Management System - Similar resource tracking and state management.