1518. 换酒问题
本来想用递归，结果好久也没搞定，还是看提示做出来的。
class Solution:
def numWaterBottles(self, numBottles: int, numExchange: int) -> int:
result, remain = 0, 0
result += numBottles
remain = numBottles #剩下的空瓶
#print(f'result: {result } remain:{remain}')
while remain >= numExchange:
result += remain//numExchange
remain = remain//numExchange + remain%numExchange
#print(f'result: {result } remain:{remain}')
return result
