Fifteen dominoes have been arranged in a 5x6 grid below. The '==' and '!' represent fault lines in the arrangement. A fault line is a straight line going all the way through the arrangement without hitting any of the dominoes.

Rearrange the dominoes so that there are no fault lines in the grid.

+--+--+--+--+--+--+
|     !  |  |  |  |
+--+--+  +  +  +  +
|     !  |  |  |  |
+==+==+==+==+==+==+
|  |  !  |     |  |
+  +  +  +--+--+  +
|  |  !  |     |  |
+==+==+==+==+==+==+
|     !     |     |
+--+--+--+--+--+--+

Brian, with your permission:

What about to prove that there is no 6x6 similar grid without a fault line?

Edited on December 19, 2005, 10:21 am

Posted by pcbouhid on 2005-12-19 08:02:10