思路:

先计算下money元钱能买多少瓶汽水, 也就有多少个空瓶,再让空瓶兑换汽水, 空瓶数=余的空瓶数+第二次兑换的空瓶数, 依次循环类推;

public class Main {

    public int totalNum(int money, int m, int n) {
        if (money <= 0) {
            return 0;
        }

        int num = money / m;
        int kongping = num;

        while (kongping / n > 0) {
            int temp = kongping / n;
            num += temp;
            kongping = temp + kongping % n;
        }

        return num;
    }
}