MikeMirzayanov's blog

User Lists
By MikeMirzayanov, history, 8 years ago, translation, In English

Hello,

We are launching new feature on Codeforces, in early beta mode. I hope it will be useful to many active users of the web-site. Now you can create, manage and use the "user lists".

Menu

Partially, it is a kind of generalization of "friends." You can create a list of users interesting to you (you can create many lists) and, using the list, filter the results of rounds, quickly analyze what problems are solved in the problemset, etc. This feature is a helpful tool for coaching — I'm using it. By combining in a list of all practicing students, it is easy to pick up problems that have not been solved (and even not attempted) by any student.

A user list has name and a pair of two relatively secret keys & mdash; one for view/usage and one for editing. For example, here is the key to view a list of ACM-ICPC students at Saratov State U for autumn of 2015: 15c68c2cf878267d59373d1e56be8c9a

This means that on some pages, you can use the optional parameter ?list=key to apply the list. Here is an example of the screen by the link http://codeforces.com/problemset/page/3?list=15c68c2cf878267d59373d1e56be8c9a:

Yeah, in the recent training I can give the problems 538H - Summer Dichotomy and 538G - Berserk Robot . In additional information the first number indicates the number of users solved problem, and the second is the number users attempted problem. Codeforces searches solutions/attempts not only for this particular problem, but all the possibilities of its use (say, someone can solve it in other division or in a mashup).

There are additional controls to make it more comfortable to use lists:

At the moment, the lists can be applied:

  • in the problemset (shown number of solvers/attempters for each problem)
  • in list of rounds/trainings in Gym (shown number of solvers/attempters for each problem)
  • on the standings page (to filter the rows)

I remind you that the functionality is in early beta mode & mdash; there may be some issues. We will return to development and bug fixing after ACM-ICPC Regional Contest NEERC 2015.

And what other use of the lists can offer you?

  • Vote: I like it
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  • Vote: I do not like it

Comments Comments (22)
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8 years ago, # |
← Rev. 3   Vote: I like it +48 Vote: I do not like it

Codeforces is already awesome....everything it gives is now a bonus. Just don't make things complicated(like Topcoder)..codeforces is complete and easy to use. Keep codeforces as simple as possible.

I am not against of this change. This User-List feature is great too.

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8 years ago, # |
← Rev. 2   Vote: I like it 0 Vote: I do not like it

what is the different between list and friend standing (in standing page)? and is there any way to creat a list of whole city or country or organization?

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    8 years ago, # ^ |
      Vote: I like it +1 Vote: I do not like it

    Okay, to answer the first question. You can think of it as splitting your "friends" into categories. Plus, it's easier to remove a list of people which are only temporary "friends".

    I like your second suggestion. It would be cool to easily compare yourself against people in your country.

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8 years ago, # |
  Vote: I like it +59 Vote: I do not like it

Please make a feature that we can know whom has us as a friend.

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8 years ago, # |
← Rev. 2   Vote: I like it +5 Vote: I do not like it

It will much better if we can see the names of solvers/attempters.

Nice feature! Thanks

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8 years ago, # |
  Vote: I like it +18 Vote: I do not like it

Sugestion: Problem lists. If you're training with a university or a team, it's bad to make a big contest, it would be better to make shareable lists of problems for people to solve in infinite time.

It's like a shareable personal tagging of problems, maybe.

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8 years ago, # |
  Vote: I like it +36 Vote: I do not like it

May you make a feature to filter problemset status with a special list?

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

Hi! This is a very useful idea! I think it will be great.

I have a few suggestions.

First, I think there should a be a way (for example a list) so we would be able to compare ourselves with other categories. People in our city, country, another country, etc. (What I really want is to be able to compare myself with all the people in my school. They are a lot and I can't put them all in my friends, but they all have our school name as a tag.)

This list function is great. I hope it gets implemented soon. It would be great to have an option like "friends only" for each of our lists. Or we would be able to combine two of our lists. I want to be able to apply two of the lists in the problemset instead of creating another one containing the users in those two lists.

That's all. Thank you do much for the great site. It's user-friendly, easy to use, and can be helpful to all types of computer programmers.

Oh and I have a problem with adding members to a list. I created a list, but when I try to add members I get an error: "Can't perform the requested action"

I know you said it's beta mode, but you also said that the lists could be applied in the problemset, etc.

Thanks a lot again. :)

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

Hello Mike. When I use lists in the problemset, I want to be able to go from page to page without the list function disabling. I don't want to have to change the URL everytime. Thanks for this great feature. :)

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8 years ago, # |
  Vote: I like it +7 Vote: I do not like it

How to share lists between users? Is the feature implemented yet?

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

    This feature has been implemented, but I found that I can't delete the list that was shared with me. I want to know how to delete it. QAQ

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

Is this only available to users who have participated in 20+ contests? After my 20th contest I noticed it and told my friends about a new feature, but they said it's been around for years now.

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

Can you implement so that its possible to sort the problemset according to the number of solves from my list?

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

It would be nice to be able to filter rating page by user-list too, just like organization/country.

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

MikeMirzayanov, It would be really helpful if I get to see a problem status according to list on the problem/contest page also.

I add problems in mashup from a collection of problems(in google sheets) in which only links for problem page are provided. There is no (easy) way to check if a problem is tried/solved by people in my list.

For now I have written a script that gets all the tried problems list of me and my friend from API and then check it against the problem name. But, that cannot be done if there are more people in the list.

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4 years ago, # |
← Rev. 2   Vote: I like it +1 Vote: I do not like it

It would good idea When me and my friends going to have a contest with gym/archive problems we can not find good problems please add a feature to filter the problems that attempted/solved by users of list before that would great.

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