Puzzleup 2014 (9) Knights and Rooks - 西洋棋

題目網址: http://www.puzzleup.com/2014/
http://www.puzzleup.com/2014/puzzle/?250

答題時限: ９月25日７ＰＭ－比賽結束（約12月17日）
加分時限: ９月25日７ＰＭ－10月１日６：５９ＰＭ

答對可得基本分１００分。答案可上傳５次，每改１次答案從基本分扣２０分。　
比賽期間內可隨時上傳答案，加分時限內答對第ｎ天加（６－ｎ）分　 　　 　　
另依題目的難易有額外加分（如有８０％的人這題答錯，答對者加８０分）　　

◆Knights and Rooks

In how many different ways can two knights and two rooks be placed on a
standard chessboard so that no one attacks the others?

If this question had been asked for a 4x4 board than the answer would be 88.
Four of those are as follows.

在一個標準西洋棋盤上放入兩個騎士及兩個城堡使其皆不攻擊其他棋子有幾種放法？

若題目改問 4x4 的棋盤則答案為 88。
以下為其中四種配置。

Ｒ Ｒ Ｒ Ｒ
Ｒ Ｎ Ｎ Ｒ
Ｎ Ｒ Ｒ Ｎ
Ｎ Ｎ Ｎ Ｎ

--
2012 Q4 (#1GAyHf0z)、2013 Q3 (#1I0ef8KE) 都在排國王

這次終於換排別的棋子了嗎 XD

--
'Oh, Harry, don't you see?' Hermione breathed. 'If she could have done
one thing to make absolutely sure that every single person in this school
will read your interview, it was banning it!'
---'Harry Potter and the order of the phoenix', P513

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