Community contributions to clash of code which were more recently approved seem to show up significantly more frequently than older problems. I’ve had the same one twice in a row multiple times. It would make more sense if the problems I’ve done recently didn’t show up for a while so that I have less of a chance of instantly recalling the solution. Aren’t there enough contributions that I can go one day without playing the same one twice? Is this a bug?
This thread should answer your questions:
Actually, you’re right, there is an “issue” with the current CoC match-making. We realized it during the first Clash Wars event.
The system does look for clash exercices that have been the least played among players in the lobby, then sorts it according to its difficulty (community rating), then takes one at random in the top results.
I believe this could be improved to take into account the time since players played a clash exercise. It’s in the devs’ bug backlog.