It is preferable that you attach images to your post instead of linking to an image site, which may be unreliable. I've attached the image you linked to.
Also, we ask that users show some effort when posting questions so we may best know how to help. Why do you think the problem may involve factoring?
Well I have to justify why the shortest path is the shortest one. I can't find any way to justify why. The shortest path I've found is 13.
Hi Ilikebugs! That's a nice problem! ;)
The shortest I've found is 13 as well and I have no "hard" justification.
Perhaps only a "fuzzy" justification is needed?
Such as that it's the shortest path the goes between the King's Lake and the King's Forest.
And we might mention that without those 2 obstacles, we could get to 9.
Btw, what makes you think it's a factorization problem?