dario2994's blog

About div1E (round #810)
By dario2994, history, 21 month(s) ago, In English

I am the coordinator of Round #810. I will be brief and clear.

The div1E problem was copied by one of the two authors, it was not a coincidence.

For this reason, the div1 part of the round is unrated. Div2 stays rated.

Sometimes known problems appear in a contest, it happened to me as an author and to any problem setter who has organized many contests. This is never a reason to make a round unrated. Today something different happened, the problem was deliberately copied and the author did not tell anything to anybody (not even to the other author). Codeforces (and me personally) condemns this behavior.

A final personal remark: I feel sad. Please future authors: do not copy problems. It's a waste of everyone's time.

  • Vote: I like it
  • +3412
  • Vote: I do not like it

Comments Comments (165)
| Write comment?
»
21 month(s) ago, # |
  Vote: I like it +124 Vote: I do not like it

That's the best.

→ Reply
»
21 month(s) ago, # |
  Vote: I like it +70 Vote: I do not like it

Great.

→ Reply
»
21 month(s) ago, # |
  Vote: I like it +63 Vote: I do not like it

zxyoi shame on you.

→ Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it +82 Vote: I do not like it

    We all mess up sometime, have mercy on him please. He has accepted his mistakes.

    → Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it +44 Vote: I do not like it

    zxyoi has already stated his regret. Although his mistake was unacceptable, at least he learned from it.

    → Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it -6 Vote: I do not like it

    Everyone makes mistakes at times, but be brave enough to accept your mistakes and learn from them

    → Reply
    • »
      »
      »
      21 month(s) ago, # ^ |
        Vote: I like it +8 Vote: I do not like it

      bruh what kind of mistake did he do

      if it weren't clear from the beggining that is is immoral it's pretty fucked up. otherwise, i'm pretty sure he already learned

      → Reply
»
21 month(s) ago, # |
  Vote: I like it +98 Vote: I do not like it

Did the author admit that he/she copied the problem?

→ Reply
»
21 month(s) ago, # |
  Vote: I like it +139 Vote: I do not like it

Thank you for the clear communication! I agree with the decision to make it unrated.

→ Reply
»
21 month(s) ago, # |
  Vote: I like it +25 Vote: I do not like it

Right way.

→ Reply
»
21 month(s) ago, # |
← Rev. 2   Vote: I like it +48 Vote: I do not like it

How about the other problems that have been suspected as being copied? For example, Div1C=Div2E. How wiill these problems turn out to be?

→ Reply
»
21 month(s) ago, # |
← Rev. 2   Vote: I like it +31 Vote: I do not like it

div2E =div1C= 2020 ICPC Shanghai C https://blog.csdn.net/qq_35577488/article/details/117813076

→ Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it +45 Vote: I do not like it

    Have you really read div2E statement? There is still a little difference between them actually

    → Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it +15 Vote: I do not like it

    The names are the same [XOR Triangles] -> [异或三角形], but the two problems are actually different (from what I understand)

    → Reply
    • »
      »
      »
      21 month(s) ago, # ^ |
        Vote: I like it +10 Vote: I do not like it

      They are actually very close, the triple in the codeforces (a xor b,b xor c,c xor a) have their xor to 0, I think it is the same problem with one extra step

      → Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    yes, same

    → Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it +1 Vote: I do not like it

    that's why initially the submission increases on div 2 E and the main reason for increasing in the submission of div-1 problem E is known by everyone. (:

    → Reply
»
21 month(s) ago, # |
  Vote: I like it +59 Vote: I do not like it

Can I still get some positive delta, I didn't solve E, plz

→ Reply
»
21 month(s) ago, # |
  Vote: I like it +121 Vote: I do not like it

"not a coincidence" = "notorious coincidence"

Anyway thanks for the clear explanation and the decision!

→ Reply
»
21 month(s) ago, # |
  Vote: I like it +9 Vote: I do not like it

It would be better if the balance of problems is considered more by future authors.

→ Reply
»
21 month(s) ago, # |
  Vote: I like it +249 Vote: I do not like it

I feel quite sad for Rhodoks if they didn't know about this and it was zxyoi's fault. They are currently getting the hate, and I'm seeing some people who are a bit too rude to them, even given the circumstances. (don't get me wrong, we have the full right to be angry, but let's take this more lightheartedly, the contest is unrated, so we only wasted 2 hours of our time)

→ Reply
  • »
    »
    21 month(s) ago, # ^ |
    ← Rev. 2   Vote: I like it +31 Vote: I do not like it

    Keeping aside the fact that some problems were copied, I would not call it a waste. Div1 A,B and C are quite good.

    → Reply
  • »
    »
    21 month(s) ago, # ^ |
    ← Rev. 2   Vote: I like it +77 Vote: I do not like it

    Rhodoks is now at the bottom of the contribution list (-154). It's so unfair for him as he tried hard to prepare other problems. I feel so sad for him.

    → Reply
»
21 month(s) ago, # |
  Vote: I like it +7 Vote: I do not like it

What about D1C=D2E?

→ Reply
»
21 month(s) ago, # |
  Vote: I like it +36 Vote: I do not like it

zxyoi, Why did you do that?

→ Reply
»
21 month(s) ago, # |
  Vote: I like it +43 Vote: I do not like it

Really thanks :) Hope my "first div1 round" will be nice next time.

→ Reply
»
21 month(s) ago, # |
  Vote: I like it +9 Vote: I do not like it

Ahh, seems like finally I will become CM, thanks for this decision.

→ Reply
»
21 month(s) ago, # |
  Vote: I like it +240 Vote: I do not like it

Please ban his account.

→ Reply
»
21 month(s) ago, # |
  Vote: I like it +22 Vote: I do not like it

Pay attention! Task (Div.2 E / Div.1 C) It is also copied! Comment with confirmation: https://codeforces.com/blog/entry/105216?#comment-935731

→ Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it +4 Vote: I do not like it

    So div2 will also be unrated or not?

    → Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it +9 Vote: I do not like it

    It didn't make div2 round worse,so I think it is not necessary to unrate div2.

    zxyoi,shame for you.

    → Reply
    • »
      »
      »
      21 month(s) ago, # ^ |
      ← Rev. 3   Vote: I like it -58 Vote: I do not like it

      First, why did you claim the round didn't get worse? Just give evidences, I could have been wrong. Div1 and div2 should be equally treated so if div2E was copied then the round should be unrated for div2 too, otherwise it would be unfair.

      Second, the difficulty gap between div2C and div2D was so big that it created a huge diffence between the rank of people who solved the first 3 question quickly compared to who didn't.

      (To those who found out that i didn't manage to solve the first 3 problems quickly enough, it has nothing to do with all of my statements above, those are all facts, btw i don't mind if i get a negative delta, i just want fairness among the ones with high rating and low rating)

      Edit: I'm sorry if you found what i wrote offensive. I was just so angry about how irresponsibly the problems were setted.

      → Reply
      • »
        »
        »
        »
        21 month(s) ago, # ^ |
        ← Rev. 2   Vote: I like it +1 Vote: I do not like it

        At least the number of solvers is not big,and in div2 there were only 30- solvers.

        I think div2E is much more easier than D,and it should be at least 150 solvers in div2. May be all of you were trying to solve D all the time?

        → Reply
»
21 month(s) ago, # |
  Vote: I like it +79 Vote: I do not like it

Just curious, will the author who copied the problem deliberately receive any penalty?

→ Reply
»
21 month(s) ago, # |
  Vote: I like it +2 Vote: I do not like it

D2E is also the original topic.Link herehttps://blog.csdn.net/qq_35577488/article/details/117813076

→ Reply
»
21 month(s) ago, # |
  Vote: I like it +58 Vote: I do not like it

Feeling sad for Rhodoks, He is getting so much hate (he is now at the bottom of the contribution list).

→ Reply
»
21 month(s) ago, # |
  Vote: I like it +52 Vote: I do not like it

zxyoi, shame on you.

→ Reply
»
21 month(s) ago, # |
← Rev. 4   Vote: I like it +20 Vote: I do not like it

Tbh that's why I like antontrygubO_o rounds.Most of his problems are original.
[Edited after ko_osaga's comment]

→ Reply
»
21 month(s) ago, # |
  Vote: I like it 0 Vote: I do not like it

I submitted div2/C 15-20 seconds before the contest ending. But it did not take the submission just showed loading and refreshed the page auto. Its weird never happened to me before! -_-

→ Reply
»
21 month(s) ago, # |
← Rev. 4   Vote: I like it 0 Vote: I do not like it

What’s the difference between copying problem deliberately or just an coincidence? Those two feel the same to the participants during the contest, and make almost the same impact to the participants. Why former should be unrated and other should not?

→ Reply
  • »
    »
    21 month(s) ago, # ^ |
    ← Rev. 2   Vote: I like it +5 Vote: I do not like it

    I guess it is unrated for a different reason, people were actually able to find the solution during the round.

    Oops, didn't read the entirety of the post. Yeah, sounds strange

    → Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it +1 Vote: I do not like it

    Exactly!

    → Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it +13 Vote: I do not like it

    If the author copied a problem deliberately and told this to only his/her friend, then the author will be able to give an unfair advantage to them.

    → Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it +117 Vote: I do not like it

    It is true that it's hard to tell the difference from the participant perspective, but I think there is a better reason for unrating: it sends a message that plagiarizing problems is not acceptable and will be punished.

    Let's say the round remains rated. The author is berated by the community and receives tons of downvotes, but at the end of the day their round still gets to enter CF history and contribute to the rating of thousands of users. So there would still be incentive to do this again.

    → Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Some participants can find the solution to the problem and pass it very quickly while others will spend a long time to solve it or be unable to solve it. The formers would get higher performance marks easily, which is very unfair to other participants. Unfair competition is meaningless, lose its goal while participants lose time.

    → Reply
»
21 month(s) ago, # |
  Vote: I like it 0 Vote: I do not like it

Apparently zxyoi has already received his scolding

But why do that... just why...

→ Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Maybe he did it for problemsetter reward($300)?

    → Reply
»
21 month(s) ago, # |
  Vote: I like it 0 Vote: I do not like it

What was the need for this for them ?? But really liked the straightforwardness from your side.

→ Reply
»
21 month(s) ago, # |
  Vote: I like it +1 Vote: I do not like it

Hope these kinds of mistakes are not repeated in the future.

→ Reply
»
21 month(s) ago, # |
  Vote: I like it +3 Vote: I do not like it

Best!

→ Reply
»
21 month(s) ago, # |
  Vote: I like it +3 Vote: I do not like it

Maybe it's best way to deal with the situation temporaily.

→ Reply
»
21 month(s) ago, # |
  Vote: I like it +193 Vote: I do not like it

It is ridiculous that this blog has so many upvotes while the official announcement has a negative amount. Please, upvote the official announcement since the author of the announcement really has nothing to do with what happened.

Please, go there and upvote it, it is not fair that he gets so much negative contribution.

→ Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it +46 Vote: I do not like it

    that's impossible. The only way is for the site administration to make an exception

    → Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it +3 Vote: I do not like it

    i upvoted !!

    → Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it +37 Vote: I do not like it

    Well, when people upvote or downvote the announcement it is obvious that they actually downvote or upvote the round as a whole. Probably round announcements just should not affect the contribution at all

    → Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it +30 Vote: I do not like it

    The problem really happened in the 15 minytes after the round when everyone was outraged by what happened. You can't change your downvote to upvote because of great system, so they are stuck with that.

    → Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it +97 Vote: I do not like it

    Mike should allow changing your vote, as it is done on Reddit and other sites...

    → Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it +9 Vote: I do not like it

    Another option here is to upvote editorial or some comments by Rhodoks.

    → Reply
»
21 month(s) ago, # |
  Vote: I like it +6 Vote: I do not like it

plz also unrate div2.

→ Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Why?

    → Reply
    • »
      »
      »
      21 month(s) ago, # ^ |
      ← Rev. 3   Vote: I like it +7 Vote: I do not like it

      Apparently besides Div1E, Div1C (Div1C=Div2E) was also a duplicate. However, the author only admitted to plagiarizing Div1E, so Div2E may have just been accidental.

      The coordinators seem to be setting the precedence that accidental plagiarism (which is common) won't affect rating, but intentional plagiariam will, even though intent doesn't matter so much in terms of outcome. But since there's no obviously best solution, they just have to pick a stance and go with it.

      → Reply
»
21 month(s) ago, # |
  Vote: I like it +104 Vote: I do not like it

Is there a way to cancel upvote/downvote and revote to the other one?

→ Reply
»
21 month(s) ago, # |
  Vote: I like it 0 Vote: I do not like it

What about div2E? That was also copied lol)

→ Reply
»
21 month(s) ago, # |
  Vote: I like it 0 Vote: I do not like it

I can make div1 contest like that easy

→ Reply
»
21 month(s) ago, # |
  Vote: I like it +3 Vote: I do not like it

As a problem writer (not in cf), what the fuck

→ Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it +8 Vote: I do not like it

    same, I do prepare problems (yet not in cf), only learnt a lesson in problem setting instead of solving

    → Reply
»
21 month(s) ago, # |
  Vote: I like it 0 Vote: I do not like it

zxoi @zxoi big fan.

→ Reply
»
21 month(s) ago, # |
  Vote: I like it 0 Vote: I do not like it

Wow, so many stars aligned to make this round so bad

→ Reply
»
21 month(s) ago, # |
  Vote: I like it 0 Vote: I do not like it

Div. 2 E / Div. 1 C is same to question, except the xor constraint. Blog Solution

So unrated Div. 2?

→ Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Yes, that's why in the starting div2E has more submissions than div2D

    → Reply
»
21 month(s) ago, # |
← Rev. 2   Vote: I like it -32 Vote: I do not like it

Out of purely selfish reasons... for people who didn't solve div1E but would have gained rating during the contest, is it possible to grant only those rating changes? If not, I completely understand, but any possibility of that happening would be huge for me (and probably others as well).

Edit: the fact that div1C was also similar to an existing problem does pose some difficulty, but I feel like first, the problems are still slightly different which makes it less harmful, and second, people who copied on div1C probably also copied on div1E so people who only solved div1C probably did so legitimately. But again, it's just a random suggestion and if it's infeasible that's fine too.

→ Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it +40 Vote: I do not like it

    Granting only positive rating changes directly causes rating inflation. Even if it didn't, it seems unfair that solving E reduces your rating increase to zero.

    → Reply
    • »
      »
      »
      21 month(s) ago, # ^ |
        Vote: I like it -8 Vote: I do not like it

      Yeah that makes sense, just a little annoyed that I lost out on +80 rating but there's always next Sunday :)

      → Reply
»
21 month(s) ago, # |
  Vote: I like it +36 Vote: I do not like it

However, not only div1E is copied.

→ Reply
»
21 month(s) ago, # |
  Vote: I like it +36 Vote: I do not like it

→ Reply
»
21 month(s) ago, # |
  Vote: I like it +30 Vote: I do not like it

I'm Curious about whether the round was unrated or not if the problem wasn't copied, just a coincidence. In my opinion, the situation that someone wrote the comment of the same problem's detail during the contest is fatal, and worth to be unrated. (this has no difference from writing the solution of the problem during the contest)

→ Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it +20 Vote: I do not like it

    I think the decisive factor should be how many people AC the problem not rely on their effort in the contest.

    → Reply
  • »
    »
    21 month(s) ago, # ^ |
    ← Rev. 4   Vote: I like it +18 Vote: I do not like it

    Clearly, there were some people who tried to cheat publicly while the round was in progress, for malicious reasons (likely to make the round unrated). I think this should not be accepted.

    Also, it's hard for me to believe that the existence of the same problem in GP can yield that many submissions in such a short period. I can recall problems quite well, and I really enjoyed upsolving Div1E. But it's hard to believe that a lot of people share the same experience with me, are able to recall problems well, and happen to have solution codes on the problem.

    → Reply
»
21 month(s) ago, # |
  Vote: I like it -7 Vote: I do not like it

In fact, this is not the only round that I can find the same problem that I have done before. In the last round, Education Codeforce Round 132, I found that I have done problem C last year and problem D just this week. So I just use the code that my friend and I have wrote before the contest and the AC code we have see in a blog,(we even have wrote another blog to talk about the problem before the contest!), and get the system message that said it was a violation of the rules since we use the same code. But that was because we have done it before the contest! The rules in http://codeforces.com/blog/entry/8790 said that use the code that have been wrote before the contest is allowed, I comply with the message to plead a miscarriage of justice against me, but no one reply, There was no one to deal with it. So，

the system message：“If you have conclusive evidence that a coincidence has occurred due to the use of a common source published before the competition, write a comment to post about the round with all the details.”

the rule：“Solutions and test generators can only use source code completely written by you, with the following two exceptions: the code was written and published/distributed before the start of the round, the code is generated using tools that were written and published/distributed before the start of the round.”

They look useless！There's no administrator to reverse my misjudgment. no administrator tell me that if I need to Provide more evidence. Even if you insist on misjudging me， please let me know to Provide more evidence to prove that!

http://codeforces.com/blog/entry/8790 http://acm.hdu.edu.cn/showproblem.php?pid=4915 http://t.csdn.cn/5qwDN https://www.acwing.com/file_system/file/content/whole/index/content/6131167/

→ Reply
»
21 month(s) ago, # |
  Vote: I like it 0 Vote: I do not like it

Looking at the positive side, it's lucky that those who didn't perform well today didn't get relegated

→ Reply
»
21 month(s) ago, # |
  Vote: I like it +8 Vote: I do not like it

Man I feel sad for those who are at the to of the leaderboard in Div 1.

Imagine being soo happy that you are at the top and then this happens.

Really sad but it's necessary ig.

→ Reply
»
21 month(s) ago, # |
  Vote: I like it +146 Vote: I do not like it

Thanks for this post--I agree that this was the best possible decision.

Because this is the first instance I'm aware of in which a round was unrated due to a preexisting problem, I want to clarify the precedent being set here. In your blog, you write

Sometimes known problems appear in a contest [...] This is never a reason to make a round unrated.

Am I correct in understanding that your meaning is that a round can be unrated when a problem is intentionally copied, but not when a repeated problem appears as a coincidence? In particular, would the round have been rated if d1E was not copied by the author but instead was independently recreated by the author? (While this obviously isn't what happened today, it doesn't seem like a particularly implausible hypothetical--the problem statement is relatively simple, and I could imagine someone having the same idea.)

I would argue that the impacts of the copied problem on the contest should play a greater role than the author's intent in determining whether a round is unrated. In particular, there are a few properties of this problem that suggest that making it unrated was the correct decision:

  • The duplicated problem appeared late in the set, giving a particularly large advantage to those who were able to copy it. (For example, a duplicated d2A would be less of an issue because most participants solve d2A very quickly anyway.)
  • The duplicated problem received an extremely large number of solves relative to a typical problem of its position. This indicates that lots of people were able to copy the problem, meaning the problem had a significant influence over the ultimate standings.
  • The duplicated problem was significantly better-known in one region than in the rest of the world, giving an advantage to participants from that region.
  • The duplicated problem was solved by numerous participants very early in the contest. This means that participants who did not recognize the problem were likely motivated to spend time on a problem they had little chance of solving, further disadvantaging them in the contest.
  • A link to the past version of the duplicated problem was shared during the round, enabling more people to copy solutions.

It seems very difficult to come up with a specific set of guidelines to most effectively determine when a round should be unrated, and unrating a round only in instances of direct copying is at least a clear rule that is easy to consistently apply. On the other hand, I don't see an intrinsic justification for why an author's intent should be related to whether a round is rated, so I think there's some justification for using a different rule to determine when rounds should be unrated, or even making each decision on a case-by-case basis.

→ Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it +28 Vote: I do not like it

    I think the case of having identical problems should not be a reason of unrated contest. Regardless of how ugly it seems, the skill of searching the right problem to copy-paste, and the skill of searching for the right algorithm to apply, are not separable. Unless Googling is banned, we should consider it as a part of skill.

    So, if the author had identical problems, it should be considered as something like "having an unexpected easy solution". In this case, the author misestimated the problem difficulty, a lot.

    What I don't understand is that I don't think problem E is "easy" in that regard. I don't see how it can have so many solves, even before it became evident in the CF community. I copypasted many problems, but the scoreboard never resorted to results like this.

    → Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it +11 Vote: I do not like it

    While I agree that never unrating problem because of a copied problem is too general, I think you're downplaying the intent way too much. Imagine doctor making a mistake in a relatively hard surgery which costs patient life, doctor making a mistake in a easy surgery which costs patient life, and doctor deliberately killing a patient. First is probably not going to affect him at all- it sucks that mistakes happen (that would be same as having obscure easy to copy original), second is negligence and results at least in losing a licence, but the third one is absolutely unacceptable and deserves a super harsh punishment. Of course outcome is not that dire in CF, but deliberately going against the nature of your job is a very serious violation.

    → Reply
    • »
      »
      »
      21 month(s) ago, # ^ |
        Vote: I like it +11 Vote: I do not like it

      I agree that the intent matters in determining how to deal with the author (and in this case, the author should at the very least be permanently barred from setting problems). However, that's a separate issue from whether the round should be unrated. In my view, the purpose of making a round unrated is not to punish the author but to address issues with the preparation of the round that make it fundamentally unfair to certain contestants, and I would argue that there are certainly instances in which coincidentally duplicated problems create such an effect.

      → Reply
      • »
        »
        »
        »
        21 month(s) ago, # ^ |
          Vote: I like it +3 Vote: I do not like it

        Ok, I see what you mean now, sorry for misunderstanding you.

        → Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it +37 Vote: I do not like it

    A link to the past version of the duplicated problem was shared during the round, enabling more people to copy solutions.

    Can we agree not to do this? It is still discussing an ongoing contest; calling out problems like this should be done after the round or at least by using the clarification asking mechanism.

    → Reply
»
21 month(s) ago, # |
  Vote: I like it 0 Vote: I do not like it

Thanks for coordinator's decision to still rate it, it makes it possible for me to get a rating of 1300, otherwise I would have to wait a week for the next rated contest.

→ Reply
»
21 month(s) ago, # |
  Vote: I like it 0 Vote: I do not like it

ABOBA

→ Reply
»
21 month(s) ago, # |
  Vote: I like it +221 Vote: I do not like it

I express my regrets to the coordinators, one of the authors and all participants. It's too bad that this happened. Future authors, please don't ever do this. It is unacceptable.

But I want to once again draw your attention to the fundamental difference between this incident and accidental coincidence of problems.

These are fundamentally different cases. Life is such that the second happens and will happen in the future. We come up with problems around the same ideas. We think about the same things. We have similar ideas about the beauty and interestingness of problems.

I myself came up with hundreds of problems and dozens of them coincided with something by chance. Here is the last example: compare 1702F - Equate Multisets and https://atcoder.jp/contests/abc254/tasks/abc254_h This is what happens.

But we must understand that these are two fundamentally different situations. In the second case, we will not make the rounds non-rated — there are no such precedents and will not be. But today's case is quite different. Alas.

→ Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Is this confirmation that div1 will be unrated, but div2 will remain rated?

    → Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it +8 Vote: I do not like it

    Yeah, but the authors still should try to avoid coincidences, aren't they ?

    → Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Could you please elaborate more on how their fundamental difference leads to different decision on rated or not?

    → Reply
»
21 month(s) ago, # |
  Vote: I like it -18 Vote: I do not like it

I wonder why would zxyoi do this, likely he is just a naive child to think that people would not recognise a problem from a few years ago. And by child I mean have 12 or at most 15 years old.

→ Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it +8 Vote: I do not like it

    But he seems like at least a uni undergrad based on his profile lmao. What an actual clown to even think that he would get away with this

    → Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    i agree with you

    → Reply
»
21 month(s) ago, # |
  Vote: I like it 0 Vote: I do not like it

Great!

→ Reply
»
21 month(s) ago, # |
← Rev. 3   Vote: I like it -23 Vote: I do not like it

Hoping to have a good round!

→ Reply
»
21 month(s) ago, # |
  Vote: I like it 0 Vote: I do not like it

Great post.

→ Reply
»
21 month(s) ago, # |
  Vote: I like it +207 Vote: I do not like it

What I am going to write now is my opinion, not codeforces' opinion.

  1. It is not allowed to post comments, during an ongoing round, linking to a known problem. For some reason codeforces does not care, and the comment even received upvotes. I do care: that's shameful.
  2. Do not be offensive towards anyone. You are all screaming against one or two people, that can be painful. Stop it.
  3. Some problems of this round were very nice (div2B, div1D), it's so sad to see that everyone is ignoring the problems and focusing on the drama. I hope that some strong contestants will try upsolving div1D.
  4. The amount of downvotes on the announcement is ridiculous. The round was ok apart from div1E, which did not affect the performance of 2000 participants.
  5. There are many unexperienced participants who feel entitled. Even if they are likely just a minority, it makes the comment section toxic.
  6. Yes, the author admitted to copying. It is something that deserves my respect (admitting it, not copying).
  7. For contestants it may be the same if a problem was copied on purpose or just an unlucky coincidence, but for the image of codeforces rounds, and for the respect that users have for the platform, it is not the same.
→ Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it -33 Vote: I do not like it

    there's nothing nice about Div2B

    → Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it +1 Vote: I do not like it

    Completely agree, the idea of div2 B was really amazing.

    → Reply
»
21 month(s) ago, # |
  Vote: I like it +3 Vote: I do not like it

To prevent this, I think for future contests we need some testers or designated people who check if a problem is a duplicate from some other contest by thoroughly searching the web to the degree possible

→ Reply
»
21 month(s) ago, # |
  Vote: I like it 0 Vote: I do not like it

Unethical and ugly behavior made a return.

→ Reply
»
21 month(s) ago, # |
  Vote: I like it 0 Vote: I do not like it

get good and stop crying. if you keep complaining like this youll never get good at competitive programming

put that keyboard to some good use

→ Reply
»
21 month(s) ago, # |
  Vote: I like it +10 Vote: I do not like it

What's more, some people ask whether this contest is rated or unrated, but the answers are all "Yes". I wanna know who wrote the questions' answer during the contest.

→ Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it +70 Vote: I do not like it

    The decision to make the round unrated is not as easy as you think. There are so many things to consider and people who are answering clarifications just can misunderstand the overall situation. In many cases (and in my personal experience), authors and coordinators are trying their best to leave the contest rated. So I don't think there is someone to blame for such answers.

    → Reply
»
21 month(s) ago, # |
← Rev. 2   Vote: I like it 0 Vote: I do not like it

good

→ Reply
»
21 month(s) ago, # |
  Vote: I like it +14 Vote: I do not like it

I think it's not Rhodoks's falut.

→ Reply
»
21 month(s) ago, # |
← Rev. 2   Vote: I like it +24 Vote: I do not like it

Solve 1C for the first time, but unrated...Sad story but a warn for all future problemsetters: don't copy any problems.

Also I hope every user of CodeForces can show respect to Chinese Rounds. This contest is just a particular case. Most of the rounds made by Chinese still have a high quality. Although there may be differences between the Chinese OI and the Codeforces traditional problems, it's also a good chance to challenge yourself and try new styles of problems.

Last but not least, I think the ones who discovered the existed problem(s) can just immediately tell the problemsetters but not show them in the post. It's really unfair.

→ Reply
»
21 month(s) ago, # |
  Vote: I like it 0 Vote: I do not like it

Fortunately I went to bed instead of competing this round.

→ Reply
»
21 month(s) ago, # |
  Vote: I like it +49 Vote: I do not like it

Thanks for the clear explanation and correspondence!

I agree with the decision.

Now I think as follows:

  • If the problem was copied from somewhere

Should be unrated. In this case writer can deliberately give the person who knew the problem an advantage, and this is unfair.

  • If the problem happened to be same as somewhere else

It can't be a reason to be unrated. Only those who knew the problem had great practice.

  • If the problem happened to be same as somewhere else and the link to that problem was mentioned during the contest

This is clearly unfair, there is no difference from sharing a solution. Unrated is better in the ideal, but I wonder if it's easy to be unrated by the behavior of one participant...

→ Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it +10 Vote: I do not like it

    I agree to your reasoning in general.

    For the third case, I think we should try not to unrate the contest if that happens. Linking problems in public space is basically terrorist behavior. The person is maliciously trying to cheat in order to ruin the contest, and this can happen in any form (even with completely original problems). Unrating the contest is succumbing to those terrorists, and it will encourage malicious actors to repeat similar things again if they are afraid of losing their rating.

    I think the right answer is to never make it unrated, and make everyone realize that an unhealthy community doesn't deserve fair contest.

    I really think the plagiarism of author is a tiny issue in this incident. I think we just realized that there are more percentage of cheaters in Div1 compared to Div2.

    → Reply
»
21 month(s) ago, # |
  Vote: I like it 0 Vote: I do not like it

Do not copy problems.

This problem ruined my sleep last night.

→ Reply
»
21 month(s) ago, # |
← Rev. 2   Vote: I like it +2 Vote: I do not like it

How shocking!

Somebody tried to copy problems on CF?

Unbelievable.

→ Reply
»
21 month(s) ago, # |
  Vote: I like it +33 Vote: I do not like it

@Rhodoks's contribution... I think it's not his fault.

→ Reply
»
21 month(s) ago, # |
← Rev. 2   Vote: I like it 0 Vote: I do not like it

I think the two games should be kept complete, and they will not be rated together

→ Reply
»
21 month(s) ago, # |
← Rev. 3   Vote: I like it -8 Vote: I do not like it

Feeling sad for Rhodoks, He is getting so much hate (he is now at the bottom of the contribution list).

→ Reply
»
21 month(s) ago, # |
← Rev. 2   Vote: I like it -50 Vote: I do not like it

div2 also have similer problems such as D and E ,why div2 is still rated ? give back my scores to me ! why my contirubition is -6 , I never swear

→ Reply
  • »
    »
    21 month(s) ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Improve yourself to solve them)

    → Reply
»
21 month(s) ago, # |
  Vote: I like it +3 Vote: I do not like it

Let's upvote the editorial from Rhodoks. He doesn't deserve the downvotes man.

https://codeforces.com/blog/entry/105232

→ Reply
»
21 month(s) ago, # |
  Vote: I like it -43 Vote: I do not like it

It didn't ever come to me that red names and above would cheat on purpose, until this round #810. I do know unsporting players would team up to share ideas during the contest, but somehow I assumed most of them are just beginners..... now, I feel better, that significant percentage of the guys with higher ranking are actually, no good at all..

→ Reply
  • »
    »
    21 month(s) ago, # ^ |
    ← Rev. 5   Vote: I like it +30 Vote: I do not like it

    I don't think you can really consider this as "cheating on purpose". It's very possible for a contest to coincidentally have a similar problem, so participants that recognize said problem can retrieve their past solutions on it (if they solved it) or search for a publicly available solution. This is allowed in Codeforces.

    There were some unfortunate factors here (like how this similarity was blogged during the contest, or how this problem was more well-known in the Chinese community than for others) that destroyed any hope of actual fairness, but this does NOT imply that the individual participants that solved this problem actually cheated, let alone on purpose.

    Like, imagine if you were in a contest and you realized that the hardest problem is very similar to a problem you saw before. What would you do? Pretend like you haven't seen it before and act like you're solving it from scratch? Avoid the problem because you think it would be unethical (despite Codeforces explicitly allowing solution reuse, under certain conditions)? Rage-quit the contest because you feel that the integrity is compromised? Regardless of what you consider to be the appropriate course of action, I don't see how you can judge those who make a different choice (specifically, retrieving and submitting past solutions) as "cheating on purpose".

    Note that the fact that this copying was deliberate (which is universally agreed as unethical, including by the regretful offender) was not known to the participants during the contest.

    → Reply
    • »
      »
      »
      21 month(s) ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      well, imagine you happened to start with hardest problem?, or imagine you keep refreshing the blog to check for hint? ....... without communications (aka. cheat group), it strike me that that many forks accomplished it. you can have all your excuses, but to me, those excuses is too naive to accept it without feeling insulted.

      → Reply
»
21 month(s) ago, # |
  Vote: I like it +6 Vote: I do not like it

I narrowly avoided like a -120.

→ Reply
»
21 month(s) ago, # |
  Vote: I like it 0 Vote: I do not like it

thinking this round will be great

→ Reply
»
21 month(s) ago, # |
← Rev. 3   Vote: I like it -10 Vote: I do not like it

Codeforces and I… it’s « Codeforces and I ».

→ Reply
»
21 month(s) ago, # |
  Vote: I like it +21 Vote: I do not like it

He has accepted his mistakes.

→ Reply