You are standing in the very corner of a 10 X 10 grid of dots. How many different ways are there to get to the opposite corner of the grid? You must travel through every node once, and only once. You cannot travel diagonally, and you may not go outside of the overall perimeter.

(In reply to Solution by Jonathan Chang)

Sorry Jonathan, you didn't start in a corner, this is not a solution to the problem.
The four corners are found at the co-ordinates (1,1) (1,10) (10,1) and (10,10).  There are four different possibilities allowed by the problem, see below.

Start           End
 (1,1)       (10,10)
 (1,10)      (10,1)
 (10,10)     (1,1)
 (10,1)      (1,10)

I am looking forward at your solution.

Posted by Hugo on 2005-04-19 16:19:46