The service has some restrictions on input size, memory and execution time. They should be more than fair for what you need, but if for some reason you think they are too restrictive, let me know and we'll have a look.
For those who are wondering what QD means, perhaps you should move your nose off the screen. :p It's right there, ffs! Some people make challenges out of anything and nothing... ;)
The only thing I'm not sure about is how hard it is to understand what is going on exactly. You should be able to deduce a few things, but perhaps it is not enough to power your light bulb. When you have deduced a fair number of things and can't make any more sense of it, feel free to contact me. If needed, I'll extend the cheat sheet a bit.
So.. two years and still no solvers. There are no words to express my disappointment in all of you. ;)
At least some of you have found a little bit of information, but I haven't heard of anyone figuring out the meaning of the input codes. Figuring out that part is probably the most important thing to do, if only because it is essential to eventually getting the solution. The outputs should help a lot in figuring this out, as well as just trying out various inputs.
Here are two little hints for those who want it:
The second example in the cheat sheet, besides providing a way to get some easy outputs, is also useful in figuring out some crucial properties of the codes. The different outputs betray some core structures. This should give you some substructures that might be helpful elsewhere.
One final thing: just like with QD, don't be too literal with the ??s. :)