数组模拟实现。

class ParkingSystem {
public:
    int pos[3];

    ParkingSystem(int big, int medium, int small) {
        pos[0] = big;
        pos[1] = medium;
        pos[2] = small;
    }

    bool addCar(int carType) {
        return pos[carType - 1] -- > 0;
    }
};