http://delphiforfun.org/Programs/knights_tour.htm

A technique known as  Warnsdorf's heuristic allows us to make much better choices for next move than random selection.  The heuristic, discovered by H. C. von Warnsdorf in 1823 tells us to select as our next move  the one which has the fewest choices for moving on from there.  This heuristic works so well that , although I have implemented backtracking to remove bad choices, I have yet to see a move retracted while making a tour

Warnsdorf's idea works in linear time!
Amazing power of human mind.. :)

Try to solve a little bit more difficult version of the problem ;)
1596. Knight Mare ( http://acm.timus.ru/problem.aspx?space=1&num=1596 )