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1603. 设计停车系统

English Version

题目描述

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 。

 

示例 1：

输入：
["ParkingSystem", "addCar", "addCar", "addCar", "addCar"]
[[1, 1, 0], [1], [2], [3], [1]]
输出：
[null, true, true, false, false]

解释：
ParkingSystem parkingSystem = new ParkingSystem(1, 1, 0);
parkingSystem.addCar(1); // 返回 true ，因为有 1 个空的大车位
parkingSystem.addCar(2); // 返回 true ，因为有 1 个空的中车位
parkingSystem.addCar(3); // 返回 false ，因为没有空的小车位
parkingSystem.addCar(1); // 返回 false ，因为没有空的大车位，唯一一个大车位已经被占据了

 

提示：

  • 0 <= big, medium, small <= 1000
  • carType 取值为 1， 2 或 3
  • 最多会调用 addCar 函数 1000 次

解法

方法一：模拟

为每种车维护一个计数器，初始值为车位的数目。此后，每来一辆车，就将对应类型的计数器减 1。当计数器为 0 时，说明车位已满。

时间复杂度 $O(1)$，空间复杂度 $O(1)$。

Python3

class ParkingSystem:

    def __init__(self, big: int, medium: int, small: int):
        self.cnt = [0, big, medium, small]

    def addCar(self, carType: int) -> bool:
        if self.cnt[carType] == 0:
            return False
        self.cnt[carType] -= 1
        return True


# Your ParkingSystem object will be instantiated and called as such:
# obj = ParkingSystem(big, medium, small)
# param_1 = obj.addCar(carType)

Java

class ParkingSystem {
    private int[] cnt;

    public ParkingSystem(int big, int medium, int small) {
        cnt = new int[]{0, big, medium, small};
    }

    public boolean addCar(int carType) {
        if (cnt[carType] == 0) {
            return false;
        }
        --cnt[carType];
        return true;
    }
}

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

C++

class ParkingSystem {
public:
    vector<int> cnt;

    ParkingSystem(int big, int medium, int small) {
        cnt = {0, big, medium, small};
    }

    bool addCar(int carType) {
        if (cnt[carType] == 0) return false;
        --cnt[carType];
        return true;
    }
};

/**
 * Your ParkingSystem object will be instantiated and called as such:
 * ParkingSystem* obj = new ParkingSystem(big, medium, small);
 * bool param_1 = obj->addCar(carType);
 */

Go

type ParkingSystem struct {
	cnt []int
}

func Constructor(big int, medium int, small int) ParkingSystem {
	return ParkingSystem{[]int{0, big, medium, small}}
}

func (this *ParkingSystem) AddCar(carType int) bool {
	if this.cnt[carType] == 0 {
		return false
	}
	this.cnt[carType]--
	return true
}

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

Rust

struct ParkingSystem {
    list: [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 {
            list: [big, medium, small]
        }
    }

    fn add_car(&mut self, car_type: i32) -> bool {
        let i = (car_type - 1) as usize;
        if self.list[i] == 0 {
            return false;
        }
        self.list[i] -= 1;
        true
    }
}

/**
 * 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);
 */

...