[其他] 組合,看不懂題目的限制?(已解決)
On a circular array with n positions, we wish to
place the integers 1, 2, . . . , r in order, clockwise, such that consecutive
integers, including the pair (r, 1), are not in adjacent positions
on the array. Arrangements obtained by rotation are considered
the same. In how many ways can this be done?
搞不清楚那種情況不能出現 ~"~
例如在r=3的情況,可以出現
1
3 嗎?
我知道不能 3
1 , 因為是順時針看,而它又不容許有(r,1)
那上面那個 1
3 可以嗎? @@" 謝謝~
還有 確定一下 它說不能出現連續整數
是既不能有 2 也不允許 3
3 2 對吧?
謝謝大家~ m_ _m
(我突然覺得我搞錯題目的意思了~(呆滯))
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※ 編輯: ilmvm0679 來自: 61.231.116.230 (03/12 21:43)
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