[理工] 離散 排列問題

看板Grad-ProbAsk作者 (白嘻嘻)時間10年前 (2013/09/03 21:53), 編輯推噓0(003)
留言3則, 2人參與, 最新討論串2/3 (看更多)
Consider the permutations of 1, 2, 3, 4. The permutation 1432 is said to have one ascent (since 1<4) and two descents (since 4>3 and 3>2). Suppose a permutation of 1, 2,3, ... ,m has k ascents, for 0<=k<=m-1. How many descents does the permutation have? 102成大資工數學的題目 不知正確答案為何 我算的答案是m-1-k 但是覺得似乎太容易些 所以請教大家一下 -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 114.26.71.193

09/03 23:02, , 1F
yes 是m-1-k
09/03 23:02, 1F

09/03 23:06, , 2F
剛算也是 m-1-k,這題配分多少阿
09/03 23:06, 2F

09/03 23:07, , 3F
好像10分吧 成大數學 本來向來就很簡單= =
09/03 23:07, 3F
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