I actually "solved" it in less than 2min

來源: 於 2012-12-28 19:07:24 [舊帖] [給我悄悄話] 本文已被閱讀：次

I found this.

http://math.stackexchange.com/questions/261826/what-is-three-different-way-to-solve-this-probability-combinatorics-problem-of

剛開始以為您又要搞腦筋急轉彎，故意把d改成了?d.