kira201's blog

How good is Codeforces Plagiarism Checker ?
By kira201, history, 4 years ago, In English

In the codeforces round 709, I made a submission from my alt account for div2A to see if the codeforces plagiarism checker really works. To be honest, I thought initially that the round was unrated because of no formal announcement, so I dared to try it out. Eventually, ended up losing rating ,lol. Well, it doesn't matter.

Here are the two submissions:110629586 and 110636692 with exact 100% match. But, the plagiarism wasn't detected. So, I wondered if several such submissions go unnoticed every contest to due to this bug or am I missing something. Feel free to comment, I don't care about the downvotes as well but if this is a serious issue, MikeMirzayanov please look into it.

  • Vote: I like it
  • +34
  • Vote: I do not like it

Comments Comments (10)
| Write comment?
»
4 years ago, # |
  Vote: I like it +18 Vote: I do not like it

My guess is the plagiarism checker won't be run on all the questions in a contest because it is highly likely that one solution to trivial problems (implementation wise) such as the one that you have shared is similar to another.

PS: I don't think having an alt account is a good idea. Not sure about the exact rules though.

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

    Yeah, I understand in many cases div2A and B are trivial, so the logic can be same. But what about the case when there is a 100% code match as above, like those who copy and paste the solution received from their friends or groups.

    → Reply
»
4 years ago, # |
  Vote: I like it +22 Vote: I do not like it

It is not exactly the same code, because one uses "GNU C++17" compiler and the other uses "GNU C++17 (64)", so when the compiler replaces the libraries, maybe it will produce a different code, but yeah, definitely the Code Plagiarism Checker should detect this kind of things.

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

I got plagiarized for the first question. My sol — 109233079, Other sol — 109231770 So, imo plag checker runs on every problem even if sol is very trivial

→ Reply
»
4 years ago, # |
  Vote: I like it +70 Vote: I do not like it

Sure, if a problem is like print a*b we don't run anti-plagiarism. And the fact that the codes coincide can only mean that the participants use the same template code. It is strange to punish for this.

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

    MikeMirzayanov Is plagiarism checking still done on Codeforces? I was checking it for some of the recent contests and did not find any skipped solutions.

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

At what percentage are the two solutions plagarized?

→ Reply
»
16 months ago, # |
  Vote: I like it -19 Vote: I do not like it

How much rating did you lost ? kira201

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

    Bro looking at your contest history and contest submissions it's clear to see why you're asking this question lol.

    → Reply
»
16 months ago, # |
← Rev. 2   Vote: I like it 0 Vote: I do not like it

I think plagiarism is only detected when there's a similarity between two problems, not just one, and plagiarism is still run on trivial problems.

→ Reply