It seems that both North Korean teams which got the top 2 places in the December 2014 long contest (@msm1993 and @rns4) cheated by using multiple accounts. It seems that it’s not enough that they participate in teams, which makes it very difficult for the rest of us who participate individually to compete against them, but now they also used multiple accounts. Moreover, by using multiple accounts, they exceeded the 500 submissions limit for the challenge problem (which is probably one of the main reasons for which they needed a second account).
- see this submission of @msm1993 : http://www.codechef.com/viewsolution/5601121
- see this submission of @kutengine : http://www.codechef.com/viewsolution/5601080
You can see the similarities in variable definitions and in the functions used (particularly in namespace CR).
@rns4 used @new_bad_coder as the 2nd account:
- see this submissions by @rns4 : http://www.codechef.com/viewsolution/5601036
- see this submission by @new_bad_coder : http://www.codechef.com/viewsolution/5600907
See the variable definitions at the beginning of the code and the function doitkhs().
I guess each of the 2 teams wanted to win so badly, that they needed to make more than 500 submissions for the challenge problem in order to tune their solutions more - and using a second account was the only way to achieve that.
I already sent an email to firstname.lastname@example.org and I hope the admins will take appropriate action. In my opinion punishing such cases is all the more important as the 2 teams obtained the top 2 places in the contest and would otherwise be rewarded with cash prizes.
Edit: It seems that the long contest rankings were updated after DEC’14 and @msm1993 was not considered a cheater (and, thus, they won the contest). I think this is disappointing, because the cheating is obvious if one looks at @msm1993’s submissions and at @kutengine’s submissions (@kutengine’s submissions contain just a part of @msm1993’s submissions, because they were testing only some specific parts of the solution to the challenge problem). To me it seems clear that @msm1993 used the @kutengine account in order to be able to make more than 500 submissions at the challenge problem (in fact, they made more than 700 submissions from both accounts in total). This way they were able to tune their algorithms much better to the official test cases, which was one of the key elements in them getting the best score in the challenge problem.
Edit 2: The @msm1993 cheating case has now been addressed by the Codechef team and his submissions were disqualified from the contest. I apologize to the Codechef team for accusing them of not doing anything about it. It seems that the Codechef team was busy with organizing ICPC onsite regionals (which I agree should have the highest priority, given Codechef’s mission). It’s just the process of looking into cheating cases is not transparent and, from the outside, it seemed that nothing was being done. Sorry for that. Anyway, all’s well that ends well.