题目网址: http://www.puzzleup.com/2015/
http://www.puzzleup.com/2015/puzzle/?6
答题时限: ９月３日７ＰＭ－比赛结束（约12月16日）
加分时限: ９月３日７ＰＭ－９月８日６：５９ＰＭ
答对可得基本分１００分。答案可上传５次，每改１次答案从基本分扣２０分。　
比赛期间内可随时上传答案，加分时限内答对第ｎ天加（６－ｎ）分　 　　 　　
另依题目的难易有额外加分（如有８０％的人这题答错，答对者加８０分）　　
◆CHESS COLORS
You have an 8x8 table on a computer screen with all squares colored to white.
In each step you will select any square and as a result all the squares on
the same row and column -including the selected square itself- will switch
their colors (white becomes black, and black becomes white).
What is the minimum number of steps required for obtaining a standard colored
chessboard?
在一个电脑萤幕上有着一个 8x8 的全白方格。
每一步你选择其中一格，
这会使所有与该格同行同列的格子(包含该格本身)切换颜色(白格变黑、黑格变白)。
试问最少需要几步才会得到一个标准的西洋棋盘颜色？