[gthulhu]

A specific and very efficient pruning yes.

I have updated my algorithm (when I worked on the step-by-step visualization process, I realized that sometimes it was doing worthless extra steps), then it is faster than the first version. The new version is online. You can also upload your own puzzles now.

For 16x16 TetraVex puzzles with 23 different colors, it takes, for about 80% of them, less than 10 milliseconds on a regular computer with no parallelization (I use two instances: one on a Surface Pro 3 and another on a EC2 t2.micro).

For the others, it takes about 100 to 200 milliseconds to solve.

Then, IMO, it takes 'almost' the same time to generate a solution than to check it.

[thomasahle]

I sure seems very fast. I'm just wondering if you know anything about how fast it would be on a worst-case NxN board? When you write 'sub exponential', do you mean that literally? Or do you just mean that it seems fast?

[gthulhu]

Hi. Sorry for the late reply: I do not check often this account. Feel free to contact me via the contact page (where my email address is displayed) on my website to ask me any question!