1603. Design Parking System

Design a parking system for a parking lot. The parking lot 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 object of the ParkingSystem class. The number of slots for each parking space are given as part of the constructor.
• bool 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 of three kinds: big, medium, or small, which are represented by 1, 2, and 3 respectively. A car can only park in a parking space of its carType. If there is no space available, return false, else park the car in that size space and return true.

Example 1:

Input:
["ParkingSystem", "addCar", "addCar", "addCar", "addCar"]
[[1, 1, 0], [1], [2], [3], [1]]
Output:
[null, true, true, false, false]
Explanation:
ParkingSystem parkingSystem = new ParkingSystem(1, 1, 0);
parkingSystem.addCar(1); // return true because there is 1 available slot for a big car
parkingSystem.addCar(2); // return true because there is 1 available slot for a medium car
parkingSystem.addCar(3); // return false because there is no available slot for a small car
parkingSystem.addCar(1); // return false because there is no available slot for a big car. It is already occupied.

Constraints:

• 0 <= big, medium, small <= 1000
• carType is 1, 2, or 3
• At most 1000 calls will be made to addCar

Solutions (Rust)

1. Solution

struct ParkingSystem {
    slots: [i32; 3],
}


/**
 * `&self` means the method takes an immutable reference.
 * If you need a mutable reference, change it to `&mut self` instead.
 */
impl ParkingSystem {
    fn new(big: i32, medium: i32, small: i32) -> Self {
        Self {slots: [big, medium, small]}
    }

    fn add_car(&mut self, car_type: i32) -> bool {
        if self.slots[car_type as usize - 1] > 0 {
            self.slots[car_type as usize - 1] -= 1;

            true
        } else {
            false
        }
    }
}

/**
 * Your ParkingSystem object will be instantiated and called as such:
 * let obj = ParkingSystem::new(big, medium, small);
 * let ret_1: bool = obj.add_car(carType);
 */