[機經] 本月JJ請教
38、老師從20人名單裡選3個,但是不能選連著的3個人,問多少種方式
bigur解答:C3(20)-(20-2)=1122
我對"不能選連著的3個人"這邊不是很懂,有人可以說明一下嗎?
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