> Tbh, I think it's a terrible question.

I think it's a terrible _interview_ question, partly due to it's "IQ test" nature, but mostly because it's a pretty hard problem and I really wouldn't expect someone to be able to just spew out a solution the first time they hear it.

Of course, the process would be more about the interviewer observing your thought process, seeing how you develop a notation for solving this thing which you almost certainly don't have any pre-existing notation for, etc. I just really wouldn't expect much progress in the space of 5 to 10 minutes, although I am basing this on the "13 marbles" version of the problem.