Water Bottles

给一个数字表示汽水的个数, 另一个表示喝完后空瓶换新需要的比例. 求一共能喝几瓶.

模拟一下

class Solution {
    public int numWaterBottles(int numBottles, int numExchange) {
        int res = 0;
        int empty = 0;
        do { 
            res += numBottles;
            empty += numBottles;
            int newNumBottles = empty / numExchange;
            empty %= numExchange;
            numBottles = newNumBottles;
        } while(numBottles > 0);
        return res;
    }
}