So today I came across two puzzling questions which I immediately recognised as problems formulated in a competition I am taking part in. Luckily, the OP did not formulate these questions well, so they got downvoted and closed. This behaviour of course is undesirable and wrong. I flagged the two questions and asked the mods to delete them but nevertheless it is sad that people actually try to cheat that boldly...
What can we as the community do to stop these cheating attempts?
I believe we (you) have done everything we could:
Downvote, close, flag, delete. (And what Geobits said: leave a comment, to let other users know!)
This happens every couple of months for another competition, and usually the questions are fairly bad, so they don't get through anyway. If some OP should ever take the time to formulate the question properly, we might not be able to catch it, but even then, these competitions are rarely looking for golfed code.
Often the competitions are looking for efficient solutions, and if inexperienced users try to pull off a fastest-code or fastest-algorithm challenge it usually goes sufficiently wrong for the question not to survive.
I think you're already doing the right thing. If you recognize it as such, you should flag it (assuming you don't have the privilege to close yet). Downvote is clearly an option as well ("this post is not useful").
The one thing I'd add is that it could also be helpful to comment on the post itself to notify others, along with a link to the competition (for evidence) if possible.
People are always going to try to find ways to "cheat", so just handle them as they come up.
I would add one thing to the existing answers: mention it in chat. If you can provide a link to the questions from the contest, that gets enough people on the alert to spot attempts to post the rest of them as well.
