have you looked at my Depth-First Search approach to generating unicursal mazes? one can pick any start/end point, and block any grid coordinate. i quickly noticed that there were no solutions to certain combinations. do you know about the Hamiltonian path problem?

@daliwali - I will look at your approach further. Concerning certain combinations with no solutions, there are two possibilities: You are using an odd number of points and incorrectly set the start and/or end point OR you are using an even # of points and incorrectly set the end point.

seated at the bar, a few stools away: "i'll have whatever they're having"

To clarify an earlier comment, with an odd # of points, there are only certain places where you can place a start point with the end point always needing to an end on an odd # when counting from the start point. With an even # of points, you can place the start point anywhere but the end point must end on an even # when counting from the start point.