优化下这段代码：if(IsResGenerate && IsEnGenerate) { int rand = Random.Range(0, 4); // 根据随机数选择车辆 if (rand == 0) { GameObject car = Instantiate(BlueCar, transform.position, transform.rotation); CarSp = car.GetComponent<Car>(); CarSp.Path(Index); GM.ResIncrease(true); } else if (rand == 1) { GameObject car = Instantiate(GreyCar, transform.position, transform.rotation); CarSp = car.GetComponent<Car>(); CarSp.Path(Index); GM.ResIncrease(true); } else if (rand == 2) { GameObject car = Instantiate(EnCar, transform.position, transform.rotation); CarSp = car.GetComponent<Car>(); CarSp.Path(Index); GM.EnIncrease(true); } else { GameObject car = Instantiate(RedCar, transform.position, transform.rotation); CarSp = car.GetComponent<Car>(); CarSp.Path(Index); GM.ResIncrease(true); } } else if (IsResGenerate) { int rand = Random.Range(0, 3); // 根据随机数选择车辆 if (rand == 0) { GameObject car = Instantiate(BlueCar, transform.position, transform.rotation); CarSp = car.GetComponent<Car>(); CarSp.Path(Index); GM.ResIncrease(true); } else if (rand == 1) { GameObject car = Instantiate(GreyCar, transform.position, transform.rotation); CarSp = car.GetComponent<Car>(); CarSp.Path(Index); GM.ResIncrease(true); } else { GameObject car = Instantiate(RedCar, transform.position, transform.rotation);

可以将重复的代码提取出来，用一个数组来存储车辆预制体，这样可以避免重复代码，提高代码的可读性和可维护性，优化后的代码如下所示：

if(IsResGenerate && IsEnGenerate)        
{             
    int rand = Random.Range(0, 4);              
    // 根据随机数选择车辆
    GameObject[] cars = {BlueCar, GreyCar, EnCar, RedCar};
    GameObject car = Instantiate(cars[rand], transform.position, transform.rotation);
    CarSp = car.GetComponent<Car>();
    CarSp.Path(Index);
    if(rand == 2)
    {
        GM.EnIncrease(true);
    }
    else
    {
        GM.ResIncrease(true);
    }
}         
else if (IsResGenerate)         
{             
    int rand = Random.Range(0, 3);              
    // 根据随机数选择车辆
    GameObject[] cars = {BlueCar, GreyCar, RedCar};
    GameObject car = Instantiate(cars[rand], transform.position, transform.rotation);
    CarSp = car.GetComponent<Car>();
    CarSp.Path(Index);
    GM.ResIncrease(true);
}