You may all be aware that @kgcstar and @kutengine are very successful in Codechef contests, particularly in the monthly Long Contests. Both @kgcstar and @kutengine won the monthly long contests several times. Personally, I have never been able to rank higher than any of the two in any contest that I participated (always because they obtained a better score than mine in the challenge problem). Although I don’t enjoy “not winning” I did enjoy reading the code of their challenge problem submissions and I even learnt a thing or two from their winning challenge problem submissions , so there was something good in this for me, too. Sometimes, after seeing many different strategies implemented in their code, I concluded that I would have never had the time to try out so many things in a 10-day contest and that they definitely deserved to win at least for the amount of effort they put into their challenge problem submissions (trying out many strategies with various parameters, etc.).
However, yesterday, in a Codeforces thread discussing the recent ACM ICPC World Finals, someone posted a link to an article mentioning the good results of the North Korean teams in the Codechef contests (they were mostly talking about June, July, August, September and October 2013, where @kutengine and @kgcstar obtained really good results). The article was in Russian, so I used Google Translate to read it in English. The word team was mentioned every time, but I thought that maybe the translation was bad (they also mentioned team ACRush several times ) or that maybe the writer of the article wasn’t aware that Codechef contests are not team-based contests, but rather individual-based contests.
Nevertheless, I was intrigued by this and searched on Google a bit more. I found several other articles mentioning that the teams from the North Korean universities won the Codechef contests. I discarded this again because i thought that maybe the writer of the article wasn’t aware that Codechef contests are not team contests.
But then I came across this article which specifically mentions that a group of four students from Kimchaek University of Technology won the June 2013 Codechef long contest (the winner of that contest was @kutengine).
Note that I am not questioning the quality of their submissions in Codechef contests - those submissions were clearly good and based on those submissions they clearly deserved to win (when they indeed won). However, at least for the challenge problem, having a team of people working on it definitely makes it easier to win than being just a single individual.
Edit 1: I edited this post in order to make it visible among the recent posts. Since the July 2014 long contest is under way, maybe someone who can provide a proper answer will see this post.
Edit 2: It seems that the name of the @kutengine user changed from Myongsu Cha to SongChol Ryu recently, which seems to suggest that there are indeed multiple people using the same account. On the other hand, it has been brought to my attention that Codechef’s code of conduct actually allows team participation, as long as the whole team uses only one account (see here). This is unfortunate, in my opinion, because it makes it very difficult for individual participants to compete properly against teams of people. Can @admin comment on why team participation is permitted in Codechef contests?