Привет, Codeforces!
Настало время новостей. Надеюсь, вам понравится!
Мы немного опускаем границу рейтинга для оранжевых участников. Таким образом, теперь оранжевый рейтинг (и звание мастер) будет начинаться от 2100 единиц рейтинга.
Нижняя граница рейтинга для легендарных гроссмейстеров увеличена до 3000 единиц рейтинга. Таким образом, прямо сейчас в сообществе 14 участников соответствуют этому требованию. Настоящие легенды!
Для раундов серии «только для Div. 2» увеличена верхняя граница рейтинга для официального участия. Теперь все, чей рейтинг менее 2100 (то есть до кандидатов в мастера включительно) смогут зарегистрироваться на такие раунды для участия в конкурсе, их рейтинг будет обновлён по результатам раунда. Мы не планируем повышать сложность Div. 2 раундов. Практика показывает, что задачи таких раундов и сейчас интересны и полезны участникам «ниже оранжевого».
Для совмещенных Div. 1 + Div. 2 раундов распределение по дивизионам остается без изменения, то есть в Div. 1 редакцию раунда будут попадать участники от 1900 единиц рейтинга и выше.
В качестве эксперимента мы планируем проводить раунды упрощенной сложности (Div. 3). В таких раундах в официальные результаты будут попадать участники с рейтингами менее 1600. Мы планируем включать в такие раунды простые учебные задачи, которые помогут начинающим участникам освоить получить навыки и новые знания в режиме настоящего соревнования. Так как даже в Div. 2 раундах регулярно находятся любители самоутвердиться из числа первого дивизиона (зарегистрировали новый аккаунт, заняли высокое место в Div. 2 раунде), то имеет смысл ожидать подобное неспортивное поведение и в Div. 3 раундах. Мы будем исключать из официальной таблицы результатов Div. 3 раунда и помещать в отдельную комнату всех тех, кого достоверно сложно назвать реальным участником. Аккаунты, которые существенно участвовали менее чем в 2-х рейтинговых раундах (то есть решили хотя бы одну задачу) до начала Div. 3 раунда, и те, кто когда-либо набирал 1900 или более единиц рейтинга не будут попадать в официальную таблицу и будут определены в отдельные комнаты. Однако, это не означает отсутствие пересчета рейтинга для них. Таким образом, рейтинг будет обновлен у всех пользователей, чей рейтинг строго меньше 1600 на момент старта раунда. Возможно, мы будем экспериментировать с определением кого следует считать достоверным участником Div. 3, а кого — нет. И да, спасибо VLamarca за пост с обсуждением идеи Div.3 раундов!
Обновление границ рейтингов и изменение цветов не мгновенный процесс. По этой причине прямо сейчас на сайте еще могут быть устаревшая информация. Мы работаем над тем, чтобы применить заявленные изменения в течение суток.
Надеюсь, вы рады этим новостям.
— MikeMirzayanov
I am sure, the concept of Div. 3 round will definitely help many beginners.
Thanks, hope to see you on Codeforces Round 479 (Div. 3)!
It was a good decision (about DIV3)!
It is very important for beginners (it's to hard for schoolboy from 5-7 forms to participate in DIV2)
I want to help with problems for DIV3 rounds (without payments :) )
Please tell me, what I need to do?
It is a down at the product. It will get more user from leetcode! Just run my codeforces!
I have some questions (and I think not only me):
1) Will problems in Div. 2 and Div. 3 cross?
1.1) Is that crossing going to be permanent?
2) As I understand, rating system is something like that(answer if its not so):
Div. 3 (-INF; 1600)
Div. 2 [1600; 2100)
Div. 1 [2100; +INF)
3) Problems for Div. 3 rounds will be made by 1600+ rate users, or other can make something too?
Sorry for my poor English :D
for point 2)
as I understood, the rating system will be like this:
but the "Div. 2 Only" rounds will now affect the rating of purple users as well (i.e., it will be official for all participants with less than 2100 rating)
Maybe is upper bound for Div. 2 to move to 2100? Than "Div. 2 Only" will be real "Div. 2 Only".
Hi my rating is 887. Can i participate in div2 and div3?
Yes you can. But you are more likely to do well in div 3 compared to div 2.
As a bonus, it will also encourage top to mid level users to give a try to peoblem setting. And writing problems for Div 3 contest can be a good way to start. This may increase the frequency of rounds to. So overall we are moving in the right direction. :)
It's a great Idea. Thanks MikeMirzayanov & CF team for your relentless efforts :)
It is a down at the product. It will get more user from leetcode! Just run my codeforces!
In my opinion, this is a terrible decision. Hello rating inflation!
I wrote a little more about it here.
Why do you think so? Current anti-inflation heuristics work rather well and I don't see reason why they will break after changes.
From my past experience, any time there is a combined div1 + 2 round, the div1 participants are cushioned by thousands of div2 users even if they perform terribly relative to div1 alone. Same thing would happen with these candidate masters in 1900-2100 range. clearly this would lead to devaluation of ratings!
As for the anti-inflation practices, I recall that they only apply to div 1. I couldn't find it after a quick search, so if this is different, please send me the link.
About Rating
Let's look how it will work in practice.
Afaik I proved this is wrong and directly leads to rating inflation
Haha, nobody cares of your opinion, l o s e r
On another note, I really hope that div3 contest does not influence the frequency of div2 or div1 contests. They are already extremely infrequent and at inconvenient times for many players.
Фиолетовым не будет оптимальнее пропускать div1/div2 раунды и участвовать только в div2 only, чтоб абузить рейтинг?
А ты сюда за абузом рейтинга пришёл?)
Он и так уже не фиолетовый)
Как по мне, то будет наоборот, только больше будешь падать. То, что ты обогнал 3к людей с рейтингом ниже, твой рейтинг не особо увеличивает. А в то же время, как показывает практика, люди с рейтингом 1900-2100 далеко не всегда пишут на топ див2 и с большой вероятностью найдется либо твинк либо синий, что решит больше тебя -> станет выше тебя -> ты падаешь в рейтинге.
I hope div2 contests don't become rare like div1(of course not as rare as div1) after this update..
Div 3 rounds will be prepared by separate people. They will not affect Div.1/Div.2 rounds.
Who can set div3 contests? blue as a lower bound or specific people like educational rounds ?
Right now I'm planning to run them by my students in Saratov State U. We will ask help of community in case of
lucklack of ideas or time to prepare such rounds.lack*
Nice improvement. Do we restrict new user to only join Div 3 contest?
I like this decision personally, as it motivates more to be div1.
Hmmm, so now some Div2 rounds are for people below 2100 and some for people below 1900 (based on whether or not there is a Div1 also)? Why the inconsecvence tho?
Can't wait to see the changes in practice, but for my perspective this will another the transition between div 1 and 2, and will make div 2 rounds more competitive.
Thanks for the update Mike and CF team! It's nice to know that CF is always trying to improve and open to changes like this :)
after 3 years of coding
i will fight in #Div_3 -_-
So the problems in div 3 are easier than problems in div 2 and problems in div 2 are easier than problems in div 1,right?
please don't reduce no. of DIV2 contest.
Yes,the number of DIV2 contests must remain the same.
Mike, I truly appreciate how well you listen to the community! Those changes look good and are a great boost to those around purple.
I would suggest adding a new milestone to the rating of 2800, since the range of IGM is now huge. Perhaps borrowing the unofficial term "super grandmaster" from chess?
I am more for increasing Grandmaster from 2500 — 2750 (also that is increasing of both yellow zones for 50). So International Grandmaster could be from 2750-3000.
Why not keep the Grandmaster lower bound at 2400 but just increase the Grandmaster-International Grandmaster boundary to 2700?
You just don't want red to be further away from you
Yeah, increasing the boundaries would be better and would even out the color band ranges.
Currently: {200, 200, 100, 200, 400} are the range gaps starting from CM.
With Grandmaster at 2500 and International Grandmaster at 2750, we would have {200, 200, 200, 250, 250}
Can something be done about this before it's too late? MikeMirzayanov
Is it rated for purple contestant in the education round?
I think yes, since Educational rounds have been rated only for Div 2 , so they will fall under "rounds for div2 only".
Yes
Thank you.
MikeMirzayanov , Div.3 , thats a great step taken for beginners.Although i needed it desparately 1 year ago
I think this will motivate people in rating 1900-2100 to participate in "Div2 only" contests and avoid giving Div1 contests. I think you should come up with a solution to tackle this scenario.
Let's look how it will work in practice. If you are right we will adopt the rules.
Also, I have seen people getting more than +400(1500 -> 1900) rating changes by topping div2 contests.
In such a case a person with 2100 rating can get +300, to go RED.
This implies, a person can become RED without ever giving a div1 contest.
Yeah I agree but staying in red is the challenge. Moreover topping a div2 round isn't an easy task and now CM's are rated. So I don't think someone can jump to red without being actually that good.
Yeah, but for me, becoming Red is a coveted achievement.
Plus in my opinion Div2 contests are based on solving tasks quickly, and Div1 tasks are based on solving tougher problems.
cool, so now any tom dick can get this red shit.
you simply cannot compare a red user that had 2400 rating before this shit happened, and one (actually 100's) that are going to get red due to this shit
Well, I have seen people giving only div1+div2 contests to become red :P
I think so. I became purple in a DIV2 round (not "DIV2 only") with 11th place and got +200 rating long time ago. I think it is not good because those with 2000 rating could get red or orange in luck.
I've been in 1900-2000 (maybe 1850~1950 lol) for a very long time and I think getting a high place in "DIV2 only" is much more easier than even getting +50 in a DIV1 round (and it is true for me in the past several rounds).
I do think it is not a great idea to let purple to participate in "Div2 only" contests. I think 2A and 2B is a waste of time for me.
upd: And now I get yellow in luck.
Glad to see div.3, really nice for beginners support! Small idea to improve this even farther: why not set the division border to 1500? Just registered user goes to div.2 first and then falls to div.3 if he's really the person this type of contest is meant for. No need in all the heuristics about distinguishing between first and second accounts.
Div.3 отличная возможность для новичков "потренировать" какие-то базовые алгоритмы. Когда первый Div.3 раунд?)
Вот уже, 06.05.2018 в 17:05MSK
Wow! What a change of codeforce's.
Now, is the educational round rated for div3 only or div2 as well.
Oh no, that means I am in div. 3 now and not in div. 2. Thats quite painful.
Work a bit hard and you will leave it soon .
I really like div 3 rounds !
For my opinion combination of changing master to 2100 and rating increase for only div 2 rounds are not good! On this way you removed problem from rating 1950-2050 and moved to 2150-2200. Many coders will compete only in div 2 rounds and that is bad.
I think one of that two things would be enough and really will solve problem, combination is bad.
I don't think this is a good idea.
Div 1 contests are already quite rare. Now that 2100 and below can participate in Div2-only rounds, there is even less pressure to make Div1 versions of rounds. Plus, with the new Div 3 (I'm not sure what the point is, Div1A and Div1B are good problems for 1600-rated contestants) there will be even less attention paid to Div1.
It is true that for 1900-2100 rated people, Div2 contests are still a good level. I remember when I made division 1, there was a huge jump in difficulty, which was a little disorienting. But I also think it is a good rite of passage, and forcing 1900s to do Div1 contests will make them better in the long run.
I think so too. It's true that something needed to be changed but this is too much. Changing div 1 and Candidate Master lower bound to 2000 might solve the problem already.
So what is the difficulty of div 3 contests? (when comparing to div 2 difficulty) 1.A- 2.A 3.B 4.C 5.D ?
I don't know any more than you do but seems to me like its going to be more like AABBC.
I have an idea, we could change our rank from point to some kind of medal, and the rank would be reset per 6 months
newbies like me are happy now thanks .
Will it be easier to become over 2200 rating? I mean if I'm around 2180 and play within 100 rank. I think there's a challenge between 1900 to 2200 rating now. I don't know how much will it be after 2099 rating can take part in Div.2 Only.
not 2180 but 2080 rating
More chances to lose rating!
Will the div3 rounds be rated for participants with rating between 1600 and 1900(Experts)?
By that logic participants with rating >= 1900 can participate in div2 and div1,
participants with rating < 1600 can participate in div2 and div3
and Experts only get to play div2 rounds. It seems a bit unfair for Experts.
As is said before the rating will be updated for all users whose rating is strictly less than 1600 at the time of the start of a round. I think those rating >=1600 can participate in div3 round but will be unrated.
One of my goals for 2018 was to reach Master and I was looking forward to celebrating the day I made it. Now that it's just going to be given to me... I feel unfulfilled.
Same, but I don't mind it :D
can i still compete in div 2??
I wanna say I agree with this and this would definitely help many beginners blablabla. BUT I have to say that it is no good in doing this.never.nope. First I have to say that I don't agree div1+2 mode at all.Because it makes a huge gap between the two rounds.1850-2050 is a really huge gap.People with all levels can be stuck in this.And the worst thing is after training hard,they found that they can hardly improve there score.And then they get frustrated and quit.(or stay training and become masters) Actually Div2 is not needed.All people sit in a same room can be a better choise.I don't know the original idea about Div1+2 mode.If some of the div1 guys thinks 2A and 2B is a waste of time to them,then 1A and 1B might also be a waste of time for Petr and tourist. If there is no need to seperate them from div1 to hold a div0,then there is no need to seperate some people from div2 to hold a div1.Things shall be merged,all people play together and then newbees can grow up. And now I sadly see that you goes a totally wrong way. Now there is a new div,and you think that shall help the beginners?wrong. First,the old gap is still alive(1850-2050),and the new gap is comming(1550-1750).In short,there would be two gaps,and the beginners shall face the same frustrated situations,two times. Second,you put 20 children together and no adults,and they will never learn how to speak.And if children lives TOGETHER with adults,they will learn.Same question,isn't it. Finally,100 years later we would have div1-20,totally 20 divs in our codeforces.(ofcause ,with 200+ colors).
Regarding your question about why there should be more than one division, I would say it is a problem setting issue. It's pretty hard to come up with truly challenging problems to very good people while being fair. A lot of people can set up a good contest for Div 2, but it would be unfair to let a guy like yancouto compete in such contest. The idea of not allowing really good players on tournaments is true for most competitions, like chess, football, etc. It is possible to host a lot of Div 2 contests and frankly, they are good and challenging for thousands of people.
But whenever you find someone to set up a Div 1 contest, I really like the merge idea. In fact, that's pretty much what CS Academy does. If you are a beginner, you are probably going to perform badly compared to the very good coders. But that is how it is, right? ICPC, Codejam, TCO, etc.
However, considering the way things are now, I don't think purple is high enough to be forbidden in Div 2 contests. Most purples won't solve Div 1 D so these changes make sense for me. Let's see how they work.
Idea is that if there's a Div1, it's too hard for many participants (so not really interesting) but it's somewhat easy for problem setter to add div2 AB problems (comparing to setting all the problems for Div1) and make it more interesting for these participants.
My apopogize as I thought we must wait 100 years then we can enjoy div 20. I was naive. The time we must wait is far shorter.
division partition technique.. :D specially good for beginners level but crucial for div2 :p
Возможно будет, как раньше, кандитам участвовать "вне конкурса" в div2 раундах?
Thanks mikeMirzayanov for Div 3.
WoW finally div3 ,, i wanted this to happen the moment i joined codeforces (4 years) and surprisingly codeforces did it ,,thanks codeforces
Poor my title... I lost legendary grandmaster in mere few days even I don't participate contest OAQ
you will always be dreamoon the grandmaster in our heart.
And we will remember sorry_dreamoon too :)
sorry_dreamoon :'D
also zscoder lost his journey from gray to lgm X_X
is div3 like a div2 educational round ?
This is a appreciable move because it will increase more participation in DIV3 regardless of fear of ratings drop and increase competitive spirit :) .Thanks Mike!
People between 1900 and 2100 are basically in div. 1.5 now.
While updates are still rolling, maybe we should assign distinguishable colors to international masters and GMs? Just a matter of style. They seem a bit worthless if there is no difference between GM and IGM on the leaderboard. Maybe something like this:
I think that 1.5div-title and div3 update is great, by the way.
theenks mike.
mid expert so easy peasssyyy. 1550 rating, div 3 contest, top 50 -> easy 1750
master so easy peasyyyy. 2050 rating, div 2 contest, top 50 -> easy 2250 if you top 10, then enjoy international master easy peasy
predictions: we will see VLamarca or similar user complaining to allow [2100, 2300] users to participate in div2 contests in near future (at max 2 months) since entire [1900,2100] will eventually shift to that range.
i see almost everyone with rating [1500, 2100] will get +100 — +200 in its rating easy peasy.
E869120 you make great graphs, a request to please also compare number of huge increase in no of experts/masters in few div3/div2 contest
"2050 rating, div 2 contest, top 50 -> easy 2250" When I had 1883 rating(about 150 less than your example) I got +100 for top 20. So for top 50, i think 2050 will probably become no more than 2125 and most likely will get about 2075-2100 rating if even that.
seeing how top 50 in div2 now gets +100, I think the new change would also makes it close to +100, as you have more 1900-2100 range participating. I really don't like how this is going. Feels like it's going to be a speed contest instead. Like if you solve 5 problems, you get increased rating, if you solve 4, then it's really a matter of who solve 4 faster.
With this change expert users (1600-1900) lose really much. We can participate officially only on div2. Lots of people below 1600 will only participate in div3, while purple users will be able to come down to div2. So experts have to beat most of the purple users in order to improve to div1. I think this update will make a huge gap between purple and blue users.
do not worry much :D all of them are going to gradually move to 2200+ easily and won't take part in next div2 and will never participate again in any div1
<- With occassional appearance of lazy purple handlers.
Кодфорсец адаптируется к наплыву индусов)))
So there will be three types of contests at the same time?
for example when VK round 3 is on there will be official round, div1 round, div2 round and div3 round or just as usual?
So sometimes we will see that there are three types of rounds simultaneously?
Div.1, Div.2, Div.3 rounds or just as usual?
How will Div. 1,2, and 3 share problems during contests?
Me: How much divisions can be on cf?
Mike:
(Actually div3 is very good idea, thank you Mike)
Я вообще туговатый, поэтому третий дивизион это отличная идея!
MikeMirzayanov, About the people making fake accounts, I have made a post about that some time ago, I wonder if you could take a look at it, but basically, in this post I ask why div2 contestants cannot choose to participate out of competition in div2 contests (and for div1 in div1 contests as well), I believe making this possible would make fewer people create fake accounts.
Here's the link to the post.
http://mirror.codeforces.com/blog/entry/57448
irrelevant the problem is div1 fake accounts who get top ranks in div2 contests, no problem with fake account of div2 members in div2 contest.
I think making div2 contests rated for purple coders is not good because then they will have to solve easy problems first( around 20 minutes ) which will give them little less time on solving more difficult problems (d, e) and if it's unrated for them then they can directly start from c onwards and focus more on thinking about difficult problems which helps a lot.
Ну вот :(
I cannot believe how fast this became true. Thanks a lot for giving us voice MikeMirzayanov. I wish all the success for you and your team at making competitive programming better and more popular :)
I'm a beginner , How can I know my rating..? I haven't found yet.
You have never participated in a rated contest
I have participated in recent cf rounds and even solved level A problems completely .
You only participated in the April Fools contest. That one was was a joke contest and therefore not rated.
Compete in a regular contest, and you will get a rating.
but I had participated in rated contests too please see here
No, you didn't participate in those two contests. You solved some problems after the contest was over. That's not the same thing.
So, I was hoping to reach Div1 now I'm down to Div3 :D
.
Finally becomes div1 after last contest Purple is now div2
It is good for me (Chinese) since I rarely found a div1 round at a suitable time. However, now there are some div2 round I can participate in and some I cannot, that is a little confusing. There must be a better solution because this one may lead to problems.
Is It Rated?
?detaR tI sI
metog
Is It Dated?
I had been struggled for Div. 2 problems for a long time. Glad to see the Div. 3 comes out.
Soo, what about contest frequency? Seems that there will be even less div. 1 contests now...
I'm afraid that there will really be less div. 1 contests because the purples can compete in "div. 2 only" contests.
I believe you should be more optimistic. More frequent participation from purples in CF + smother transition into div. 1 -> less people leaving the plataform after reaching candidate master -> more coders engaged in CF and more people motivating each other -> more potencial div. 1 authors in the future
I think the main problem is lack of time of coordinators raither than lack of author since suggested contests can wait for really long after being submitted. And it will escalate now..
Finally I became orange, but I feel like I'm cheating something.. :)
For this update, CMs have found their true role: the interlude between Div1 and Div2...
I just got 2200+ rating then...
Legends say that dreamoon_love_AA wants the div2 bound to raise higher to get div2 rank 1.
Jokes aside, that means I can go for div2 top 5 again? Free rating let's go!
Everyone now thinks that every single purple will get easily into top 5. What you all did not see coming is that there can only be 5 in top 5.
Are Div. 2 rounds rated for Div.3 participants ?
The international master band looks a bit thin. Maybe IM should be 2300-2500, and GM 2500-2700. Btw, I had the idea of div3 before vlamarca: http://mirror.codeforces.com/blog/entry/57783?#comment-414511 :)
Have you made millions with the idea though?
Me neither
Will problem setters be able to propose div3 contest in the future? I hope not — So problem setters are not driven away from setting hard questions instead of trivial ones that are easy to come up with.
If only trivial problems were easy to come up with :D We often struggle more to find a nice A/B than F/G for Educational rounds.
I think that when a user is registered for the first time, he should start from div3. In this way it will be harder for div1 users to ruin a div2 contest because they will need to take part in two contests. Of course that means that it will be easier to ruin a div3 contest, but as I understand div3 is just for educational purposes and not so much for competitive.
Very good update. I want to see the problems of Div 3
Can't wait to find out the problems in div 3.
What will be the relation between Div-2 and Div-3? Previously we saw that there were some overlap problems between Div-1 and Div-2.
This means I'll be in Div.3 now? -_-
The concept of div.3 is really great and problemset should be standard.In my point of view it could have been better if only Newbies and Pupils ( <1400 ) was eligible for this type of contest.Although Div.2 problemset is perfect for both Pupils and Specialists.
Candidate Masters participating in Div.2 is not a good decision at all.( I see!!I made lots of candidate masters angry.It was just my point of view . Div.2 A,B,C are wasteful for them)
Candidate masters participating in div2 is a good decision
I don't think candidate masters solve div1 D,E regularly, so what's the issue?
No clue why you get downvotes, this is 100% correct
Atcoder.jp V 2.0
I'm not a fan of this update because of decreasing the lower bound of master rating :(
Does this mean that participants with less than 1600 rating can still participate in Div. 2 rounds and get rating recalculations after the contest ?
Yes
Причина появление дивизиона 3 вызывает множество противоречий. В чём заключается его главная суть? -помочь начинающим участникам освоить получить навыки и новые знания ? Но я не совсем понимаю, почему это должно происходить в режиме соревнования ? Дух соперничества а также то самое чувство, когда кто-то решает задачу, а ты нет — все это хорошо, но хочется кое-что вспомнить. Считается, олимпиадное программирование — спортивный вид деятельности. Испокон веков человек, занимающийся тем или иным спортом, прежде чем выходить и соревноваться с другими спортсменами, тратил время на тренировки, развивал в себе те или иные навыки, получал новые знания. Шахматист, прежде чем выступать на соревнованиях, должен обладать какой-либо базой, знанием правил. И таких примеров можно приводить и приводить... Почем же тогда СП должно быть исключением из всего это ? Зачем человеку обучаться во время соревнований ? Проблема новичков не в том, что они не могут решить задачу, а в том, что они не хотят узнать что-нибудь новое, для того, чтобы решить задачу. Существует немало учебных сайтов, курсов, тот же информатикс, где все разложено по полочкам, к каждой теме приложены необходимая теория и комплект задач для оттачивания навыков. Можно к образовательным раундам добавить такую штуку: в анонсе за несколько дней объявлять темы, по которым будут задачи и рекомендуемый теоретический материал. Если приведенные темы человеку уже известны и он ими владеет, то это хороший случай потренироваться, проверить свои знания. А если же темы новые и человек раньше никогда не сталкивался с подобным, это тоже хороший случай для него узнать что-то новое для себя, а уже после на самом раунде пробовать свои силы, дорешивать и т д..
Хорошая идея объявлять темы контеста. Можно запустить марафон контестов, которые будут направлены на изучение новых тем для новичков за короткое время.
What is Round #48x? Is it a typo?
No. Right now I'm not sure about exact round number. I'll negotiate it with KAN. Hope there will be Div.1 or Div.2 round before the May, 13th.
Thanks. Hope yet another round, too. (better if time is proper for me)
Is it possible to make the Div.2 Only rated for ALL people but calculate the rating for Div.1 and Div.2 seperately?
Is there any way for Div.3 Participants to take part in Div.2 contests Unofficially.?
No. They can take part officially.
Thank you o_o
You always can start virtual participation after the contest. :)
I don't feel the virtual as interested as real contest. But virtual's helped me to improve myself. Thank you.
Sorry for my stupidity. But when we have two parralel rounds Div1 and Div2 which one should I register to if i have rating 1900? to Div1 or Div2 or I can register to any of them as official participant now.
What a great update to raring system!!
So now people whose rating between 1900 -> 2100; are they considered div.1 or div.2? Because they participate officially in both contests.
+1900 is candidate master or 2100 ????
I have the similar problem:
For me, the only changing is "the Surface of the Water"...
Как я и писал просто надо было поднять эту тему. Я сам высказывал данную проблему в своем блоге)
http://mirror.codeforces.com/blog/entry/58748
Shouldn't there be some limit on how high one's rating can go by participating in a div.3/div.2 contest? A 1550-1599 rated user could become 1st in a div.3 contest and become a candidate master without ever participating in a div.2 contest. Similarly, a 2050-2099 rated user could become a grandmaster without ever participating in a div.1 contest.
Good point.
Why isn't there an unrated participation for >1600 users?
Why i cannot register for the contest Codeforces Round 479 (Div. 3) as an unofficial participant
Why I cannot register for the contest Codeforces Round 479 (Div. 3) as an unofficial participant ?
Fixed, thanks.
I am happy that Codeforces team is constantly working on improving the platform, however, I have a serious concern about the new Div.3.
Given that the only difference between Div3 contests and usual contests is the low skill of participants, I suspect that very soon they will become uninteresting to spectators, problemsetters and sponsors.
To fix this, I suggest a new contest format for fresh coders, which has basically the following rules:
First, participants submit no more then 100 lines long solution to some particular problem. Then MikeMirzayanov selects some number (say 100) of solutions, which he considers the most elegant (preferably, some of them should be in Java, you will see later why).
He then gives the solutions for review to tourist and Petr and they choose ~20 participants who will compete in the main series of the contests.
Throughout the main contests participants will be regularly guided by tourist (C++ coders) and Petr (Java coders), constantly improving their CP skills.
The winner of such season will get an opportunity to participate in Div.1 contests regardless of his rating.
I suggest that the new format can be called "War of codes/styles" or something in that manner. I believe that such contests will make Div.3 far more spectacular as well as promote the educational spirit of the platform.
would probably work if mike tourist and petr were jobless and had nothing else to do.
That's the moment, were sponsors should take their chance
Lol, this is the most fucked up and meaningless suggestion I've ever seen on codeforces
P.S> Dude, you've placed fake support badge in your profile image, like, for real? :D
I once went on a date with a girl. I did not pay for her, and later when she asked I said I donated all my money to codeforces and showed her the badge. She said that I'm a real man and we had a great time.
Проорал в голосину
Впервые придётся подниматься в Div.2 :D
Wish everyone can have your best time in the updated Codeforces !
В задании Д http://mirror.codeforces.com/contest/975/problem/D много лишних данных. Это сделано сознательно, чтобы затруднить или просто случайно? Излишни координаты точек и свободный член в уравнении прямой. Спасибо, Леви
Hi! In http://mirror.codeforces.com/contest/975/problem/D there is a lot of redundant data: coordinates of points and coefficient B for line. Is it on purpose? Thanks, Levi
Это чтобы запутать участников.
То есть теперь есть три типа раундов:
див3 — могут участвовать те, у кого менее 1600;
див2 / educational — могут участвовать те, у кого менее 2100
див1 + див2 — в див1 с 1900, в див2 до 1900 (или до 2100 и участник может выбрать где участвовать)
Если что, то это вопрос, просьба ответить правильно ли я все понял или где-то ошибаюсь.
And with this update i lost my motivation to get into div1
Great!!! Carry on MikeMirzayanov
The problem with rating and multiple divisions is more fundamental than just inflation, and it gets worse the more divisions are there. ELO-like ratings (including the Codeforces one) have many assumptions, it is unclear how it would work with non-uniform sampling because of division boundaries, which might skew the resulting ratings.
I quickly tried to estimate the effect, and performed the following experiment. Suppose we have ELO ratings (for simplicity, pure ones, where games are for pairs of players). Let's generate player strengths with normal distribution (10k players, mean 1600, stdev 400), and use these as hidden values to determine game outcomes (i.e. probability of player 1 winning over player 2 is Sigmoid((strength1 - strength2) / 400.0)). Let's simulate the rating system, i.e. sample many pairs of players (5M in my experiment), flip a coin with the corresponding probability, and update ratings by ELO rules.
If there are no division boundaries, after many games we get the following, as expected (x axis is rating, y — actual strength):
Let's add a division boundary at 1900 (i.e. when sampling pairs, only sample the ones from the same division):
OK, we have a small artifact around 1900 — ratings for "div1" players underestimate their actual strength. Let's try to make our "div1" smaller — move the border to 2100:
The effect becomes much more visible. "Div1" ratings are heavily squashed, and difference in strength between 2100 and 2500 is much bigger than between 1500 and 2100 (btw, I've always felt that smth like this is happening with the current CF rating). Finally, what happens with 3 divisions? Let's add boundaries at 1800 and 2100:
We see that "div1" range became almost vertical on the graph! The whole 2100+ strength range is squashed to a tiny ratings range. Of course, it won't happen on CF right away (because div1 ratings are inherited from the previous system), but eventually, it might converge to something like this.
I also tried to run 10x more games, and the picture became much better:
Which makes me think that division boundaries make ratings converge much slower for higher divisions, which for short-term means squashed rating in these ranges. This also explains why div1 ratings are growing so much in div1+div2 contests — we get "free" comparisons of unconverged div1 players and converged div2 players, making div1 ratings closer to their correct values.
It would be nice to understand this effect mathematically, and adjust rating formulas to make convergence equally fast in all divisions.
You suggest that the problem involves only the velocity of convergence, but isnt it more serious than that? In your simulation you considered that div. 2 players would opt to play both div. 1 and 2 right? But if one wants to maximize his rating, isnt it better to opt to play just on div. 2?
I know that codeforces is or will be running a heuristic correction to this, but maybe a solution is to treat purples separately in div. 2 only rounds, that is, the realative position of a purple to a blue has no (or very little) effect.
Or maybe my favourite solution is to always run a compound round of div. 1 + 2 + 3 (when there is a div. 1 round of course)
The biggest problem of Codeforces is its ... ... ... slow loading, usual downs during contests. Other improvements, like Div.3, are some kind of procrastination, while not solving more serious issues.
Upd. I'm sending this message second time because after 1st time it disconnected.
can specialist perticipate in div 2?
Are Problems For Div 3 Any One with rate higher than 1600 Will make or problems or anyone ?
I do not think there will be any inflation or deflation of ratings.
I have observed that just like fake accounts abuse the system to get more ratings, real accounts can abuse the system too. Just like tourist can gain ratings just by maintaining his predicted rank which would be 1, any coder with a rating of 2100 or below can only participate in "Div 2" Only Contests and easily get over 2100 rating. Since everyone between 1900 & 2100 will do this, there will literally be a GAP formed between 1900 to 2100 rating.
It will be much much harder for a below 1900 rated contestant to get above 1900 rating as his rating would not increase as much because of a contestant rated 2100 beat him.
Rich get richer. Poor get poorer. There will be a larger barrier now.
Some of my friends used to get insane rating increases in Div1 + Div2 while I always lost ratings. But I loved and anticipated for every educational rounds as it was always an easy ratings increase for me. Same would apply for Div3 as well as merged Div2.
Fake accounts may make it even more harder for Div3 contestants to get out of 1600.
While the previous concern was rapid fluctuation above and below 1900 rating & inconsistency of being able to participate in Div1 & enthusiasm for Div2, It makes it easier now to consistently be able to give both Div1 & 2 but very very hard for under 1900 contestants to move beyond 1900 due to bad rankings due to 1900-2100 band.
1st tourist doesn't gain rating by maintaing his predicted rank 1. His predicted rank is 1.7 or something so getting rank 1 will increase his rating. In fact predicted rank will be 1 only for a user with infinite rating.
2nd someone below 1900 wouldn't lose much rating becuase of 2100 because it's expected that most probably 2100 guy would beat him on the other hand 1900 guy would have a much higher gain by beatiing 2100 guy.
Yes fake accounts is terrible problem but that's an entirely different issue.
I think the last column (the one about title/color changes) in the "Contest" section of the user profile is broken after the update. You should notice it if you see the profile of anyone who is at least orange. Maybe you should try to fix it. @MikeMirzayanov
Thanks, it will be fixed soon.
Now everyone whose rating is less than 2100 (i.e., before candidate masters) will be able to register for such rounds to participate officially
Shouldn't "before candidate masters" be "before masters"? MikeMirzayanov
Thanks, fixed
Thanks a lot
I know this is super late but I just want to express my appreciation. I participated in my first div 3 contest and felt it was just right for my level. Thank you so much!
So, problems for DIV3 is tend to be easier than them of DIV2?
Yes
As an experiment, we plan to host rounds of simplified complexity (Div. 3).
ETA of outcomes of this experiment?
Why can't I have gained 1900 points or higher in my rating to be a trusted participant in Div.3 rounds?
It is a down at the product. It will get more user from leetcode! Just run my codeforces!