answer (圖)

來源: 2009-05-01 17:38:45 [舊帖] [給我悄悄話] 本文已被閱讀:

4x4=16 gives the basic grid (see the picture), to which you can remove 1 or 3 row and column to satisfy the requirement: keep any one unit square to share only one side of red unit. Then 503x4 = 2012 gives 2012x2012 grid, to which remove 3 row and column to get 2009x2009 grid.