将一张一元的钞票,换成一分、二分和五分的硬币,每种至少十枚,有多少种方案

问题描述:

将一张一元的钞票,换成一分、二分和五分的硬币,每种至少十枚,有多少种方案

先每种拿出10枚,还有2毛,也就是说用三种硬币凑两毛钱
20个一分;18个一分,一个两分;16个一分,2个2分;15个一分,一个5分;14个一分,3个2分;13个1分,1个2分,1个5分;12个1分,4个2分;11个1分,2个2分,1个5分;10个1分,5个2分;10个1分,2个5分;9个1分,1个5分,3个2分;8个1分,2个5分,1个2分;8个1分,6个2分;7个1分,1个5分,4个2分;6个1分,2个5分,2个2分;6个1分,7个2分;5个1分,1个5分,5个2分;5个1分,3个5分;4个1分,2个5分,3个2分;4个1分,8个2分;3个1分,1个5分,6个2分;3个1分,3个5分,1个2分;2个1分,2个5分,4个2分;2个1分,9个2分;1个1分,1个5分,7个2分;1个1分,3个5分,2个2分;4个5分;10个2分
一共28种