回複:南斯拉夫奧賽題:還是2009(2.5星)

來源: 2009-05-12 10:57:08 [舊帖] [給我悄悄話] 本文已被閱讀:

n = 2009.
S1'={1,2}, S2'={2,3}, S3'={3,4}, .... S2009'={2009,1}