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Leetcode 1603. Design Parking System

Problem Statement

You are asked to design a parking system for a parking lot. The parking system has three kinds of parking spaces: big, medium, and small, with a fixed number of slots for each size.

Implement the ParkingSystem class:

• ParkingSystem(int big, int medium, int small) Initializes the object of the ParkingSystem class. The number of slots for each parking space are given as parameters.
• boolean addCar(int carType) Checks whether there is a parking space of carType for the car that wants to get into the parking lot. carType can be one of three values: 1 (big car), 2 (medium car), or 3 (small car). A car can only park in a parking space of its carType. If there is no space available, return false, otherwise park the car and return true.

Clarifying Questions

1. Are the total numbers of parking slots for each car type fixed and provided at the initialization?
   • Yes.
2. Should the solution handle concurrent car parking requests?
   • No, concurrent requests are not in the scope of this problem.
3. Are there any constraints on the values that can be passed for big, medium, and small slots?
   • Yes, constraints are provided in the problem statement:
     • 0 <= big, medium, small <= 1000
     • carType is an integer with values 1, 2, or 3.

Strategy

We will store the remaining number of slots for each car type using an array or instance variables. When a car arrives with a specific carType, we will check if there is a slot available in the corresponding category:

• Decrease the corresponding slot count if a slot is available and return true.
• Return false if no slot is available for that car type.

Code

class ParkingSystem {
    
    private int[] slots;
    
    public ParkingSystem(int big, int medium, int small) {
        slots = new int[4]; // There are three types, use index 1, 2, 3
        slots[1] = big;
        slots[2] = medium;
        slots[3] = small;
    }
    
    public boolean addCar(int carType) {
        if (slots[carType] > 0) {
            slots[carType]--;
            return true;
        } else {
            return false;
        }
    }
}

// Example Usage
// ParkingSystem obj = new ParkingSystem(big, medium, small);
// boolean param_1 = obj.addCar(carType);

Time Complexity

• Initialization: O(1) since we’re just storing three integer values.
• addCar: O(1) since checking the availability and updating the slot count is done in constant time.

This design ensures the solution is efficient while being simple and straightforward to implement.

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