There will be C(m+n,n) solutions, so for two 100 element input arrays that's 9e58 solutions, to be generated in one hour.
I think I need to upgrade my computer.
Comment on Re^2: (Golf challenge) (to cover my embarassment!)
Geez! I knew it was getting big pretty quickly but I only needed to know up as far as 7x7 (3432) so I didn't generate it any further. I had no idea that it would get that big. Thanks for the formula.