作者electrify (小狼狗)
看板Grad-ProbAsk
标题[理工] [机率]-排列组合
时间Tue Jul 21 16:31:25 2009
In how many ways can we give 6 differernt gifts to 4
students and each of them get at least one gift.
4 3 4 4
ans:4^6-{C *[3^6-C *2^6]+C *[2^6-2]+C *1}
3 2 2 1
应该还有别的方式解，不过就是想不出来..
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1F：推 youmehim:4C2 * 6C2 * 4C2 * 2! + 4 * 6C3 * 3! 07/21 17:18