# [1603. Design Parking System](https://leetcode.com/problems/design-parking-system/)


## 题目

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`

## 题目大意

请你给一个停车场设计一个停车系统。停车场总共有三种不同大小的车位：大，中和小，每种尺寸分别有固定数目的车位。

请你实现 ParkingSystem 类：

- ParkingSystem(int big, int medium, int small) 初始化 ParkingSystem 类，三个参数分别对应每种停车位的数目。
- bool addCar(int carType) 检查是否有 carType 对应的停车位。 carType 有三种类型：大，中，小，分别用数字 1， 2 和 3 表示。一辆车只能停在  carType 对应尺寸的停车位中。如果没有空车位，请返回 false ，否则将该车停入车位并返回 true 。

## 解题思路

- 简单题。分别用 3 个变量表示大，中和小车位。`addCar()` 判断这 3 个变量是否还有空车位即可。

## 代码

```go
package leetcode

type ParkingSystem struct {
	Big    int
	Medium int
	Small  int
}

func Constructor(big int, medium int, small int) ParkingSystem {
	return ParkingSystem{
		Big:    big,
		Medium: medium,
		Small:  small,
	}
}

func (this *ParkingSystem) AddCar(carType int) bool {
	switch carType {
	case 1:
		{
			if this.Big > 0 {
				this.Big--
				return true
			}
			return false
		}
	case 2:
		{
			if this.Medium > 0 {
				this.Medium--
				return true
			}
			return false
		}
	case 3:
		{
			if this.Small > 0 {
				this.Small--
				return true
			}
			return false
		}
	}
	return false
}

/**
 * Your ParkingSystem object will be instantiated and called as such:
 * obj := Constructor(big, medium, small);
 * param_1 := obj.AddCar(carType);
 */
```