The 22 dots in the figure below can be connected by 11 lines, each beginning and ending with a dot (o) and passing through 4 empty cells. Connecting lines may proceed horizontally or vertically, but not diagonally. They may change direction as often as needed, and they should not cross one another.

               +---+---+---+---+---+---+---+---+
               |   | o | o |   |   | o |   | o |
           +---+---+---+---+---+---+---+---+---+---+
           |   |   | o | o | o |   |   |   |   |   |
           +---+---+---+---+---+---+---+---+---+---+
           |   |   |   |   |   | o |   |   |   | o |
           +---+---+---+---+---+---+---+---+---+---+
           | o |   |   |   |   |   |   | o |   | o |
           +---+---+---+---+---+---+---+---+---+---+
           | o |   |   | o |   |   | o | o |   |   |
           +---+---+---+---+---+---+---+---+---+---+
           | o |   |   | o |   | o |   |   |   |   |
           +---+---+---+---+---+---+---+---+---+---+
               |   |   | o |   |   |   | o | o | 
               +---+---+---+---+---+---+---+---+

Can you do it?

Pcbouhid,
When I looked at this problem a first I saw "Connecting lines may proceed horizontally or vertically".

I jumped to the conclusion that the lines must be "straight"!
I've noted elsewhere that assumptions need to be tested.

I am impressed with the creativity shown by JoeFish and Lisa in their diagrammatic solutions.   I did find Lisa's easier to follow.

[I recall Nosher presenting a solution to a recent problem where he used RED characters in his solution; they would have made Lisa's pathways much clearer.  Nosher, how did you do that?

Et tu, Brute - Erik O.    ---- A Guess Nosher]

Edited on August 15, 2005, 1:44 pm

Posted by brianjn on 2005-08-15 13:39:19