1, was the solution to this ever posted? It seems like in the exchange with ambrus there was a pretty strong hint to the solution for challenge 1, but as to everything else - huh?

2, for future reference, a pretty unintimidating guide to sorting (just some class notes) is at a sorting

I'm kind of reading up on that during breaks. I take it that sorting is at the core of the problem space here, but maybe I'm wrong on that. Anyway, thanks for posting an interesting problem. A solution would be nice though :)