Look at these users:
FastYes
Dong5k
akatsukiLH
Uni
MahooshojoNHB
tankmagiciangirl
TankKiller
dashabi
JayYeV
tuiyigou02
Ronnoc_4
Ekaterinburg
h1me
__LH
5130309070
MonsterGentlemanLYP
d_omg
zzv
They gained high ranks of last 4 Div.2 Only contests, maybe few of them are really new users but it seems that most of them are div1 users who register new accounts for participating in div.2 only contests officially (look at their register and last visit time).
I think there is no difference in participating officially or unofficially, this only makes the competition harder for div.2 users for they should compete with div.1 users.
Anyway this is wrong, but high number of div.2 only contests is also a reason!
Please prepare contests for both divisions more often!
UPD Is there anyway to prevent from such multi accounts?
UPD2 Preparing contest for both divisions is the ideal solution! And if it is not possible, as most of the comments say it is a good idea to rate only users that have participated in at least one (or more) contests!
Weak police is not a reason to crime :/
Why ppl do that? Nobody cares about such wins, but you steal enjoy of victory from novices.
In the last div2 only contest ( результаты ) 7 of the top 10 official accounts were first timers. In this situation 'div2 only' contests are becoming less worthy of doing for div2 participants themselves.
One way of stopping it will be only taking both division rounds, but most probably that is not an option.
Another way of dealing with the situation could be like this, a user's rating change depends on his/her overall standing position. While calculating someone's position, codeforces team can only count those accounts which have participated in at least 3(or 5) rated contests.
And give the new accounts ( which have participated in only 1 or 2 rated contests ) the position of the last old ( with number of rated contests greater than 2 ) account.
This might not stop div1 participants in doing div2 contests with multiple accounts entirely, but may be this way participants will get a standing positing closer to their 'real' position. This rule could be in place for only div2 ( in all contests ) or for only 'div2 only' contests.
Perhaps participating unofficially makes one less serious in competing?
It'd always be better to have contests for both division, but hard problems (D, E div 1) are not easy to create. The solution to disable rating for one's first few contests seems to be the most reasonable one at the moment. But again, it would considerably demotivate the real newcomers.
Maybe it's good idea to create some kind of a pool for div1-E/D problems, since prepare single problem much more easier than complete contest?
If so, admins will just add 2 problems from that pool to make both div. contest from div2-only.
Not really. Great contests are usually made with balanced problem sets, which assumes that the choice for each problem was not independent from the rest.
Also you may notice that Div2 Only contests tend to be much harder than Div2 contests which take place during Div1 (sometimes E and even D are almost unsolved even by the unofficial reds). If you think about it, it does make sense. When hosting a Div2 only you don't have in mind that C, D, E are someone's A, B, C so you don't feel that they should have a fast idea or simple code solution. They're just the endgame now.
If you take such a Div2 only and add some random div1 D and E to it, you'll probably ruin it completely.
rather than number of contests participated in, i think we can see how many days before contest the user has registered on Codeforces website. if this is too low (i won't specify a cutoff here, that's for the admins to decide), then this user can register for the contest unofficially (like the "honest" participants in Div-1 do).
No, that's not a good thing. Suppose someone knew about CF, but didn't register. Then, that person heard about a new round coming up, thought "hey, might as well..." and registered not long before the contest. It isn't fair to calculate the rating in such cases differently.
Look at this contests
Codeforces Round 211 (Div. 2) (Div. 2 Only)
Codeforces Round 212 (Div. 2) (Div. 2 Only)
Codeforces Round 214 (Div. 2) (Div. 2 Only)
Codeforces Round 216 (Div. 2) (Div. 2 Only)
Codeforces Round 217 (Div. 2) (Div. 2 Only)
Codeforces Round 218 (Div. 2) (Div. 2 Only)
Codeforces Round 220 (Div. 2) (Div. 2 Only)
Codeforces Round 224 (Div. 2) (Div. 2 Only)
Codeforces Round 226 (Div. 2) (Div. 2 Only)
just 43 % of contests prepared for div 1 users ! :\
Not counting new users in the rating updates for non-new users sounds reasonable. That way, nobody is harmed — right? The question is how difficult it'd be.
Hope there will be more div.1 contests during winter holiday after that there will be fewer chances to participate in mid-night.(PS I'm chinese)
I don't think, that combined same-time-DIV1-DIV2 contests would solve the problem. Look at the past several rounds:
Codeforces Round 225 (Div. 2)
Codeforces Round 223 (Div. 2)
Codeforces Round 222 (Div. 2)
Codeforces Round 221 (Div. 2)
Codeforces Round 219 (Div. 2)
there are also several just-registered users, who tries to "win".
Suppose, that the best solution would be to complicate registration process (email confirmation, block "temporal-mail-servers") and block suspicious account in case of any reasons to consider him as a cheater or multi-acc.
Imho, 10k real users, who are fond of fair play, is better, than 100k disposable accounts.
Agree. Furthermore, I don' t think every Div1 pariticipant is cleverer, or can do better than Div2 pariticipants( just like me). For themselves, they refuse to improve their program skills. If they DO, I don't think complaining this can help.
Well, complicating the registration process won't stop the multi-accounting — just the occasional spammers (which is still a good thing :D).
Possible solution — to allow Div.1 users to participate in Div.2 only contexts, but doing rating calculations separately for each division. To make it even more interesting for Div.1 users — one may set a different memory/time limits for Div.1 — a really hard ones.
It's not so simple. Firstly, I believe you'd need a different contest whatsoever for div1, if you wanted to set different limits. Same with rating calculations. But the main problem is that the problemset of div2 contests is not suited for div1 — A,B are usually trivial for div1 (so they serve no purpose other than an element in strategy and, for a small group, unluck); C-E are usually not that hard, and if you didn't add harder problems (which are all that keeps the round from being also for div1), I suppose it'd just result in too many people getting many points for few problems, leading to, for example, your rating changing significantly just based on one fast resubmit. To illustrate: picture a div1 round where everyone solves A and B — is that OK?
It will be your decision to participate and probably lose/win some rating or just to skip the round. This way div.1 users will not have motivation to create a fake account.
Yes, but will you be happy if you lose, say, 100 more points of rating because of a small accident? I wouldn't. And this can happen much more likely in a round with 2-3 trivial (since C usually is, too) problems and 2 medium ones, as compared with a round that has 1 easy, 1-2 medium and the rest hard problems (they actually make a difference — the top of the ranklist is clearly distinguished, people who just manage to solve a hard problem also are, etc.).
I really just do D-E in div2 rounds.
Would like to suggest other solution against multi-accs for div-2:
If a unrated user takes a high place in div-2 (e.g. he hits in top-50 or top-100), then:
* he is excluded from div-2 official standings (becomes unofficial participant)
* his acc is not used for official participant's rating calculation
* his ratings automatically becomes equal to 1700
Pros:
+ If someone takes a high place in div-2, his deserved position is to be in div-1 and he gets it.
+ There are no reason to create a new acc to win in div-2 anymore: even if he's new acc gets a first div-2 place, this event is not included in acc's stats and, so, there is nothing to proud of.
+ The div-2 standing becomes more honest and real
+1, nice idea.
But I still think people will create a Div. 2 account because of other advantages like hacking. IMO it's much easier to hack some Div. 2 participant than a solution of a Div. 1 participant.
It's still meaningless for the "unrated newbie": his hacks don't bring any profit (we suppose that he gets 1700 rating after contest and becomes unofficial).
His hacks harm to hack victims only.
Why someone would spend time, if it brings him no benefits?
Because of the joy of successful hacks.