回複：世界大學生奧賽題：坐飛機（2.5星）

來源: jjmmjj 於 2009-07-03 06:30:33 [舊帖] [給我悄悄話] 本文已被閱讀：次

=1/50*(1/50+1/49+....+1/2+1/1)

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