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kuviman's blog

Ratings in groups
By kuviman, history, 9 years ago, translation, In English

Hello everyone!

Not so long ago summer trainings finished in Saratov State University, and to make it easier to monitor the success of our programmers we introduced a feature to add custom ratings. Now you also have this opportunity!

Currently rating is calculated as follows: overall rating is equal to the arithmetic mean of the ratings for each contest in which the user has participated. Contest rating depends on the ratio of problems solved by user and a number of problems solved by winner, as well as user's place in the contest. Also points for upsolving are added to the contest rating. There is a rumor that such method of calculating rating first was used in ITMO. More formally:

where

  • R — contest rating,
  • n — maximum of 50 and number of contest participants,
  • place — 1-indexed used's place in the contest,
  • solved — number of solved problems by the user,
  • maxSolved — number of solved problems by the winner,
  • upsolved — number of upsolved problems by the user,
  • problemCount — total number of problems in the contest.

If a user participated in a team, his place equals to the place of the team in this contest.

To create a custom rating in the group you have to be its manager. There can be multiple ratings in one group with different sets of contests. There is a special button to create a rating in the group sidebar:

If you press the button rating creation form will appear:

Users are added to the rating only if they have participated at least in the given percent of all contests of this rating. By default one have to participate in 50% of all the contests.

If you wish you can set rating freeze date: upsolving after that date will not affect the rating.

Also now you can view status in groups: it shows only submissions for the group contests.

Good luck with training in Codeforces groups!

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9 years ago, # |
  Vote: I like it +55 Vote: I do not like it

Thanks, that is an incredibly cool update. It will be very useful in organizing IOI preparation and such.

One request though. Could you add a way to modify the parameters of the rating formula for my ratings (it would be especially cool if you added some group/rating colorcoding).

Keep up the good work. Codeforces is becoming way more useful than it should be.

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9 years ago, # |
  Vote: I like it +14 Vote: I do not like it

That's great!

It will be also really cool if it's possible to create a contest with codeforces style (i.e. setting a different score to each problem).

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    9 years ago, # ^ |
    ← Rev. 2   Vote: I like it +13 Vote: I do not like it

    AND HACKING (i know its not helpful for study but not harmful too)

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9 years ago, # |
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Very nice update! Can you please enable filtering the results of the rating for only group members?

We train by using already existing previous contests. I made a group rating but everyone from Codeforces appears there and we would like to be able to see only the group members with the custom rating.

Thanks!

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9 years ago, # |
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Is it possible to delete a custom rating? I made two copies of the same rating scheme by mistake and cannot figure out how to delete the duplicate.

Great work though. This is a neat feature!

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    9 years ago, # ^ |
      Vote: I like it +5 Vote: I do not like it

    This feature is nearly to be ready, but it is not in the production right now. Please, wait for tomorrow!

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9 years ago, # |
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Can anybody explain the difference between {solved} and {upsolved} ? I can't find the exact meaning of the term {upsolved} on Internet.

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    9 years ago, # ^ |
      Vote: I like it +3 Vote: I do not like it

    "Solved" means "solved during the competition", while "upsolved" means "solved after the competition ends". When you take part in Codeforces round, you "solve" problems. When you look at past Codeforces rounds and submit some solution, you "upsolve" problems.

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      9 years ago, # ^ |
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      Thanks!

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      9 years ago, # ^ |
      ← Rev. 3   Vote: I like it 0 Vote: I do not like it

      It's a calque from Russian.

      Looking at the formula... am I correct in thinking that quite often you can get better R (contest ranking) by upsolving instead of solving the tasks during the contest? :)

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        9 years ago, # ^ |
          Vote: I like it +8 Vote: I do not like it

        Yes, but given that n is max of number of participants and 50, it'd have to be a fairly large contest for that to happen.

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6 years ago, # |
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I found that the add contest feature only adds contests within the group, while the external contest needs to import the scores themselves.

Is there such a need, for example, I want to use the official Codeforces competition this evening as a synchronous contest in the group and rate it, so I want to add such a feature in the external contest (citing other contests on this site).

Thank you.

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    6 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Hello MikeMirzayanov, I tried to add multiple external contests, and the result of each contest has a very large number of characters (about 70,000 characters). When I try to add a second contest and save it, the server sends out 500 errors, I guess this Probably because the size of the POST data is too large, I don't know how I should fix it (without changing the rating data). Thank you.

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