MetB's blog

Unified blog for all issues/bugs/requests considering codeforces
By MetB, history, 5 years ago, In English

Hi!

I've noticed an problem of lots of reports being put at random places and thus frequently unheard (if you ever tried to DM MikeMirzayanov, you most likely know what I'm talking about), so I take responsibility to declare this blog as a blog for collecting bug reports, proposals and other notes to mention considering the website codeforces.com Rules:

1) No off-topic. All unrelated comments will be downvoted, reported and deleted.

2) Please, share as much information related to your issue (if there is any) as you can. Simple "website doesn't work" can not be helped.

3) Other codeforces community rules apply here as well.

If you know about any unresolved issues, migrating them here will be appreciated. I'm not from CF web-design team so I have little power over the website itself so DMing me will most likely not help you (I don't prohibit it though).

Thanks and happy coding!

  • Vote: I like it
  • +257
  • Vote: I do not like it

Comments Comments (63)
| Write comment?
»
5 years ago, # |
  Vote: I like it +48 Vote: I do not like it

Proposal: When viewing problem set, add option to view only unsolved problems. Problems which we have already solved should not be visible in the list, if we have selected this option.

→ Reply
»
5 years ago, # |
  Vote: I like it +6 Vote: I do not like it

I got +130 in the last div 2 round without even being able to solve a single problem. Is this is a kind of bug? Sorry, I don't know much about codeforces rating system but getting positive delta without solving anything really bothers me. I think anyone must solve at least one problem to get positive rating changes regardless of the current rating.

→ Reply
»
5 years ago, # |
← Rev. 3   Vote: I like it +57 Vote: I do not like it

Will hacking/uphacking be expanded to

  1. older contests (before introduction of uphacking)?
  2. longer duration after contest ends?
  3. contests/mirrors in gym?

All of these would be nice, uphacking is a great feature to help promote understanding and strengthen tests, so it's unfortunate that it's not available everywhere.

→ Reply
  • »
    »
    5 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Moreover, it seems that hacks in uphacking currently apply only to the hacked solution and solutions that are submitted after the hack has taken place. If there are several already submitted solutions that fail on the same test, you need to hack each of them manually. This can be automated on the hacker's side, but it would be easier if it was automated on the system's side somehow. Successful uphacks are pretty rare, so running all solutions to the problem on each successful uphack shouldn't be a big problem, computational-wise.

    → Reply
    • »
      »
      »
      5 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      Sorry, it is not easy to implement it in this way. I don't think this is such a significant detail that it takes a lot of effort.

      → Reply
  • »
    »
    5 years ago, # ^ |
      Vote: I like it +32 Vote: I do not like it

    An uphacking can be applied only in case of a formal and complete validator and perfect solutions. For very old contests we can't guarantee it: problem writers and coordinators probably left Codeforces. Are 7 days really too short? I can extend it, but not for infinite: I like the idea of "freezing" a problem, it helps to move forward not spending much time on supporting old. For problems out of official Codeforces rounds we can't be sure about validators, so an uphacking can't be applied in general.

    → Reply
    • »
      »
      »
      5 years ago, # ^ |
        Vote: I like it +19 Vote: I do not like it

      I want to hack ko_osaga 's 44864483 in this test case. I missed hacking phase ~1 hr and there was no uphacking phase back then. Please open uphacking phase of that contest for 5 mins. :P

      Test case
      Correct soln and his answer

      I got excited when you started uphacking only to find that I cant hack him. :(

      → Reply
    • »
      »
      »
      5 years ago, # ^ |
        Vote: I like it +13 Vote: I do not like it

      Oh, wow, it's only 7 days?

      Yes, that's very short in my opinion, since a big part of Codeforces is practicing (especially for Div1 participants who don't have as many rated rounds), and people frequently practice on problems from more than a week ago.

      Even if it's difficult to add the test case, providing a simple feature to run the judge's solution & the submission on an input would be a convenient middle ground, instead of having to copy/paste and use Custom Invocation. (Basically, hacking without the same consequences of a successful hack.)

      → Reply
»
5 years ago, # |
  Vote: I like it -6 Vote: I do not like it

Please add "delete account" feature. Codechef and Atcoder already have that.

→ Reply
  • »
    »
    5 years ago, # ^ |
      Vote: I like it +42 Vote: I do not like it

    Yeah, there are definitely some people's accounts I'd like to delete. Not sure if such a feature could be abused though, maybe we could just allow deleting one's own account.

    → Reply
    • »
      »
      »
      5 years ago, # ^ |
      ← Rev. 2   Vote: I like it +3 Vote: I do not like it

      Ofcourse I meant deleting one's own account. Maybe for other accounts we can add "Report account" button.

      → Reply
      • »
        »
        »
        »
        4 years ago, # ^ |
          Vote: I like it 0 Vote: I do not like it

        I think we should be able to report comments/blogs/usernames/profile images for things that are plainly offensive and/or hate speech.

        If we're worried about too many spammy false reporting, maybe we can only allow reporting by people who have done a certain number of contests (similar to the restrictions on Coach Mode and "Trust this user" etc).

        → Reply
  • »
    »
    5 years ago, # ^ |
      Vote: I like it +34 Vote: I do not like it

    It is in a background implementation right now.

    → Reply
»
5 years ago, # |
← Rev. 2   Vote: I like it +15 Vote: I do not like it

Please add: when using Mashup contest and my one problems from Polygon with IOI format — there is table with number of points achieved, but you can't see what is maximum. Also problem with IOI format — partial points is treated as OK, and you will get "Perfect score" verdict if you get OK on all tests. Each of this problems alone doesn't make a big deal but this mean that if you have IOI problem with partial points, it's possible to recive "Perfect score" when you get partial points on all the tests, and participant can't easily find what is maximum number of points — so he might not find out that his submition is wrong!

Here is example that happend on one of my training contests, but luckily we caught it early and told participant what went wrong! This is submition of simular code, but same problems arise — 313 is treated as perfect score because it got particial points on all tests, but 450 is the maximum!

image

→ Reply
  • »
    »
    5 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Please add: when using Mashup contest and my one problems from Polygon with IOI format — there is table with number of points achieved, but you can't see what is maximum.

    I think it shows the maximum per problem. Am I wrong?

    Also problem with IOI format — partial points is treated as OK, and you will get "Perfect score" verdict if you get OK on all tests.

    I think the problem is prepared in some strange way (like used obsolete quitf(_pc(x))).

    → Reply
    • »
      »
      »
      5 years ago, # ^ |
      ← Rev. 3   Vote: I like it 0 Vote: I do not like it

      I don't see maximum, maybe you're talking about some other place. On start is all blank:

      image

      ... and as you submit you see how many points you got (but no maximum)...

      image

      For the problem with OK with partial points, here is checker I used (I used quitp(_pc(number_of_points - 16)): Link

      Is there better way to make partial points problem on Polygon? I couldn't find it, and it draw me crazy when I was preparing problem — my only problem with over 50 commits because of checker and problems with verdicts. Since then I didn't make any other partial score in one test, just making groups, that turned up really well...

      We found simular problems during testing round but just fix it best we could (then we added line if (number_of_points == 0) quitf(_WA, "all wrong")), and this problem with 313 points treated as "Perfect score" was found only during competition. T

      → Reply
»
5 years ago, # |
← Rev. 2   Vote: I like it +92 Vote: I do not like it

Request: A way to view all contests and submissions of a team

(copied from this blog)

→ Reply
  • »
    »
    5 years ago, # ^ |
      Vote: I like it +26 Vote: I do not like it

    Good idea.

    → Reply
    • »
      »
      »
      5 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      If you implement this, can you also implement all the virtual contests that the team has given? Because most teams have participated virtually in old team contests.

      → Reply
»
5 years ago, # |
  Vote: I like it +2 Vote: I do not like it

I want to share a very old problem of codeforces not having a proper blog section. A proper blog section with options of viewing blogs of different topics(like dp, graphs, etc, just like in problemset section) and types(like study material, editorial, off-topic discussions, discussing problems, etc). This would be very helpful in learning good things and I have wondered for some past months that how come a site as big as codeforces have not done anything about this problem that has been asked so many times in the past. It would be really helpful to organize everything efficiently for all the users.

→ Reply
  • »
    »
    5 years ago, # ^ |
      Vote: I like it +8 Vote: I do not like it

    What about separating blogs from bugs and questions? Ideally I would enjoy having tabs like "Bug report", "Knowledge base", "Q&A" and regular blog posts. Having a searchable bug section would reduce the number of duplicates and probably add to the visibility of some issues. "Q&A" would host questions like "why is my solution not working on this test" that do not really have a blog nature. And useful tutorials could have a button "propose moving to the knowledge base". Seriously, there are plenty of good tutorials here, but you can only find them by luck or by hitting a blog post that contains links to them — and neither is good for beginners.

    → Reply
»
5 years ago, # |
← Rev. 3   Vote: I like it +6 Vote: I do not like it

Allowing to view the people who have added you as a friend. You have 'X' friends, and you don't know who they are, sounds weird. Otherwise, it looks that the "Friends tab" is added purely for stalking purposes only.

→ Reply
»
5 years ago, # |
  Vote: I like it +4 Vote: I do not like it

I've noticed that there is no actual way to view all the blogs. If you want to see a old blog, you have to either search, or go into one's profile and look for the blog. I think it would be convenient if there were a blog menu that shows all the blogs, and can be sorted by recent, votes, etc. And maybe we can separate the announcements blogs from normal blogs.

→ Reply
»
5 years ago, # |
  Vote: I like it +5 Vote: I do not like it

Can there be a submissions vote feature,Just like for example ,We have 5 types of filters to sort the submissions by execution time,solution size,etc.If we can vote for submissions,we can sort those submissions based on number of votes and look at some good implementations.

Also,those solutions who look suspicious(if they have cheated) can be recognized easily by the negative votes.

→ Reply
»
5 years ago, # |
← Rev. 2   Vote: I like it +39 Vote: I do not like it

These three issues relating to virtual participation have been mentioned many times (especially the second one), yet have not received any response.

  1. CF-style scoreboard during virtual participation (currently, for some reason, during virtual participation, the scoreboard appears as ACM-style but turns back into CF-style after the contest ends).

  2. Currently, all submissions during virtual contest are immediately judged on system tests. It would be better if they were judged on pretests only during the contest and judged on system tests when the contest ends.

  3. Large numbers of cheaters reaching the top of unofficial standings, by copying others' code or writing their solutions before the virtual participation begins. At least one user has suggested removing virtual participants from the unofficial standings entirely (only allowing the virtual participant to see himself/herself in unofficial standings after virtual participation). See https://mirror.codeforces.com/blog/entry/78078 for more information.

→ Reply
  • »
    »
    5 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    I think virtual participation should be on unofficial standings. Without it, there's no way to compare myself with another guy that did not participated on live contest. I really don't care if cheaters are reaching the top of unofficial standings and i don't know why would i care about it.

    → Reply
»
5 years ago, # |
  Vote: I like it +13 Vote: I do not like it

If you use any extension in Firefox or Chrome so that the pages load in dark mode, like Dark Reader, the codeforces logo appears with white borders, because it is an image with a white background, this could be fixed by changing it to a PNG without a background I think it would be easy to do. Thanks for reading.

Image:
→ Reply
»
5 years ago, # |
  Vote: I like it +25 Vote: I do not like it

If I solve a problem like div2 D and then try to see the code of my submitted solution in corresponding div1 contest i.e. div1 B in this case then it is not visible.

→ Reply
»
5 years ago, # |
← Rev. 2   Vote: I like it +30 Vote: I do not like it

Radewoosh's suggestion here: https://mirror.codeforces.com/blog/entry/78358, basically a CF Wiki where helpful blog posts are stored. If implementation of this is too hard I think a lot of the Gym's code could be reused, i.e. needing "coach mode" to edit, rating difficulty, etc. The only extra thing needed would be sorting by "tags", but in the meantime we could just make sure to have descriptive titles.

→ Reply
»
5 years ago, # |
  Vote: I like it +48 Vote: I do not like it

Option to show problem rating when I open an unsolved problem (even if I have unchecked Show tags for solved problems).

Tags are sometimes too helpful towards solving a problem, so it is important to disable tags. But if now want to see the problem's rating, I need to go and find it in Problemset,

→ Reply
»
5 years ago, # |
  Vote: I like it +21 Vote: I do not like it

Proposal: Please make the friends list sorted either by ratings or lexicographically. I wonder how the friends list is currently ordered!

→ Reply
  • »
    »
    5 years ago, # ^ |
      Vote: I like it +15 Vote: I do not like it

    According to what I observed the friends list is sorted as per the date on which the account was created .Those who created account earlier will come at the top and relatively newer accounts will come at the end.

    → Reply
  • »
    »
    5 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    If Mike sees this: probably, the fastest way of implementing this is making a default list Friends, or ability to add all your friends to a list. Lists already have the sorting functionality!

    → Reply
»
5 years ago, # |
  Vote: I like it +83 Vote: I do not like it

Zoom out big (tall) images in the comments? It is so annoying to scroll through all these huge memes in the comment section. Sometimes they take the entire height of my laptop screen :(

→ Reply
»
5 years ago, # |
← Rev. 2   Vote: I like it +13 Vote: I do not like it

Proposal: After the contest ends, the number of people who solved a particular questions should be frozen. I recommend this because, when we later try to solve questions by randomly picking them up, we don't get a real idea how difficult the question was.

→ Reply
  • »
    »
    4 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    You can find this (less conveniently) by going to Standings and making sure it only shows official participation, then looking at the bottom row.

    → Reply
»
5 years ago, # |
  Vote: I like it -7 Vote: I do not like it

This blog may soon be out of recent and Top. How about pinning a link to this blog in top bar?

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

Proposal: Disable "diagonistical run after getting Wrong answer and Runtime error in C++" during virtual participation

That run would make a delay of receiving verdicts. We cannot see the testcases and diagonistic messages during virtual contests. Personally I would like to receive verdicts immediately, so it would be great to disable that almost useless run during virtuals.

(I'm not 100% sure if the delay of receiving WA or RE verdicts is caused by diagonistical run, so if there's an another reason, please point out that for me, really thanks)

Also I wonder if there can be a choice to disable diagonistics during upsolving.

→ Reply
»
5 years ago, # |
  Vote: I like it +16 Vote: I do not like it

Please add problem tags for Gym problems and acm.sgu.ru problems.

I know there's already a lot of problems on Gym and acm.sgu.ru section, and it's impossible to add proper tags to all of them, but I think with the help of {high-rated people} $$$\cup\;$$${those who add contests to Gym}, eventually a good portion of these problems will have proper tags and this will be helpful for those who want to practice a certain topic. Anyway, this would be better than nothing.

→ Reply
  • »
    »
    5 years ago, # ^ |
      Vote: I like it +8 Vote: I do not like it

    On related topic: when preparing problems in Polygon, you can add tags — actually you will recive "warning" when commiting changes if you don't add tags: Here is example

    So it is really possible that most of those problems already have tags on Polygon, MikeMirzayanov just needs to make a way to take tags from Polygon and put it in tranings/gym...

    → Reply
    • »
      »
      »
      5 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      Wow, I was unaware of this. Thanks for the information.

      → Reply
»
5 years ago, # |
  Vote: I like it +20 Vote: I do not like it

Night Mode for Codeforces Website would be really awesome.

→ Reply
»
5 years ago, # |
  Vote: I like it +31 Vote: I do not like it

Enable 2FA. There are multiple incidents of hacking CF accounts.

→ Reply
»
5 years ago, # |
  Vote: I like it +7 Vote: I do not like it

Proposal: There can be a short optional survey after the contest ends, so that the problem setters get crucial feedback.

→ Reply
»
5 years ago, # |
  Vote: I like it +3 Vote: I do not like it

If I solve a problem in a mashup contest and later go to the original problem in problemset, I can see that it's marked green (solved), but I can't find my submissions. Also I can find no way to detect using API if an user has solved a problem (same problem can be present in multiple contests: Div1, Div2, private mashup).

→ Reply
»
5 years ago, # |
  Vote: I like it -8 Vote: I do not like it

There must also be a feature which allows us to see who made us friend. We are currently able to see our friend's list but we should also be able to see who made us friends.

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

Please add a option for see users who added me as a friend.

→ Reply
»
5 years ago, # |
← Rev. 2   Vote: I like it +24 Vote: I do not like it

I think there is a problem with the search. I'm not sure it's only my machine or others too but I tried multiple browsers and all with the same problem. When I search any word it only give handles "Not blogs or anything else" many of the search I used was blogs I searched for in like a week ago without problem I even tried the examples and only worked with handles too!

→ Reply
»
4 years ago, # |
← Rev. 2   Vote: I like it +29 Vote: I do not like it

I'd love separate toggles for "show difficulty" and "show tags" for unsolved problems. Sometimes I want to see the difficulty, but I don't want to see the tags.

Right now the only way I know how to do that is to go to Problemset and scroll forever.

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

Mobile version is not working on iPhone 8 Plus (and I guess similar sized phones) for a while now. Can we fix pls? :)

→ Reply
»
4 years ago, # |
  Vote: I like it +61 Vote: I do not like it

API request: add an optional parameter in contest.standings() : seconds_since_start, to retrieve the standings as it was at seconds_since_start.

I think it's an easy thing because it's already implemented for virtual participants.

→ Reply
»
4 years ago, # |
  Vote: I like it +14 Vote: I do not like it

A proposal that has been ignored by MikeMirzayanov for a very long time now:

"A Form/mailbox or something by codeforces where people can report cases of definite cheating instead of having blogs everytime."

More context: https://mirror.codeforces.com/blog/entry/79271?#comment-649265

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

Middle button in time picker of virtual / mashup contests gives current time in UTC+3 irrespective of user's timezone. Please fix it.

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

I'm having a problem that codeforces doesn't work when I use my home WiFi but when I use cellular data it works just fine! I couldn't understand the reason to that but I was using the same WiFi to open it without problems 2-3 days ago. Anyone else facing the same issue?

→ Reply