回复：解释：|OOO|OOOOOOOOOO|O||OOOOO|.....|OOO|||O|OOOOOOOOO|O|

来源: 于 2010-06-17 08:30:56 [旧帖] [给我悄悄话] 本文已被阅读：次

m people and n rooms also right,C(m+n-1,n).