P(7,3) + C(7,2) * 2 * 3! / 2! + C(7,1)

P(7,3) + C(7,2) * 2 * 3! / 2! + C(7,1)

所有跟贴·加跟贴·新语丝读书论坛

送交者: TIDAn 于 2013-05-09, 19:37:44:

回答: 也出一道排列组合题由 whoami 于 2013-05-09, 16:21:33:

纯组合= C(7,3) + C(7,2) * 2 + C(7,1) = C(9,3) - TIDAn (120 bytes) 2013-05-09, 19:55:57 (716033)