朋友們試試這個，不知道幾星

Is it possible to color red some of the unit squares of a 2009x2009 grid so that every unit square shares a side with exactly one red square?

我有一個美妙的答案，隔幾天公布。

所有跟帖： 

• 好像是偶數行，奇數不行 -康MM- ♀ (0 bytes) () 04/22/2009 postreply 18:59:02

• 康美眉好牛啊，超牛！mad cow！真乃巾國英雄，才智勝須眉。哈。。 -戲雨飛鷹- ♀ (0 bytes) () 04/23/2009 postreply 06:59:30

• 嗯，俺們也喜飯康妹妹。 -放歌直言- ♂ (0 bytes) () 04/23/2009 postreply 09:21:32

• 回複：朋友們試試這個，不知道幾星 -dynamic- ♂ (1324 bytes) () 04/25/2009 postreply 02:36:31

• two comments... -dynamic- ♂ (275 bytes) () 04/25/2009 postreply 02:48:44

• one more comment -dynamic- ♂ (1066 bytes) () 04/25/2009 postreply 03:02:49

• 硬擺可以證明奇數不行，但是顯得很笨 -康MM- ♀ (243 bytes) () 04/25/2009 postreply 06:17:36

• 回複：硬擺可以證明奇數不行，但是顯得很笨 -外-國人- ♂ (59 bytes) () 04/29/2009 postreply 19:40:24

• answer (圖) -compound- ♂ (349 bytes) () 05/01/2009 postreply 17:38:45

• sorry, it 20grid. Then 101x20 =2020, remove 11 can be done. -compound- ♂ (0 bytes) () 05/01/2009 postreply 17:47:07

• it works only by removing odd number of row or column. -compound- ♂ (0 bytes) () 05/01/2009 postreply 17:54:38

• 全塗紅 -東瓜太郎- ♂ (8 bytes) () 07/23/2009 postreply 16:02:45