Mikemirzyanov1's blog

Bug Report !!!!
By Mikemirzyanov1, history, 4 years ago, In English

Hello everyone.

I think I have found a very huge bug in the Codeforces System which can potentially lead to destroying the purpose of Codeforces.

Alright so here is something I found.

During Div2/Div1 contests people are divided into groups and placed in different rooms for hacking purposes.

Suppose Alice is participating in Div2 contest and she solves a problem say problem B. She then has the option to lock the problem so that she can hack other people in her room. Locking a problem allows one to see another person's code for the same problem in the same room.

So far good, now begins the mischievous part.

To mess with someone from her room say Bob who has also solved problem B, Alice copies his code and submits it from her alternate account without making a single change in the code. What this will do is trigger the automatic plagiarism checker and Bob would get screwed up for having the same code as some other participant.

Alice has multiple accounts on Codeforces and she has the power to screw up everyone in her room for all the problems she solves

MikeMirzyanov Please look into this.

Also, provide suggestions if any in the comment section to tackle this problem.

P.S. Can someone in the comment section provide the What would happen if we use 100% of our brain meme I could not find it.

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Comments Comments (16)
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4 years ago, # |
← Rev. 3   Vote: I like it -19 Vote: I do not like it

You cannot lock a solution till you make an AC submission for it (As far as I am aware). So its totally pointless.

Something like this is plain stupid though. 100 accounts to kill 100 participants. Ain't nobody got time for that. The contest will be over before)

They guy may as well solve the next problem to gain better ranking...

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4 years ago, # |
← Rev. 2   Vote: I like it -14 Vote: I do not like it

Original comment:

It's impossible to directly copy other's code via hack.

Please stop posting such messy blogs.

BTW, your handle is interesting :)

Edited:

As other said, codeforces is smart enough to detect this.

Honestly, the title is too excited.

I hate this, so I was so angry.

Sorry for offensing.

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

    If one can see the code he/she can type it I think.

    BTW nice profile picture.

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

      Manually type it?

      • You must type almost every single character correctly.
      • You are wasting a lot of time.
      • You are ruining the victim.

      What's the point of it?

      Profile picture? yeah a lot of people hate this.

      No offense, care about your contribution plz.

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

    Ever heard of image to text converters? Download image process it and done. You've got the code. Its written as computer text so it is pretty easy to convert and you won't need except like some basic of A.I as characters are the same.(it is not a handwriting)

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      4 years ago, # ^ |
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      Are you talking about google lens??

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        4 years ago, # ^ |
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        umm, I don't know this app. But any application that can simply copy the text(with spaces and new lines) will work. But such an application doesn't have to be smart enough to detect different types of letters as all letters are written in one font.

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

I won't say anything about that bug (or not a bug),

But no need for bad words man.

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4 years ago, # |
← Rev. 2   Vote: I like it +7 Vote: I do not like it

I think the later submission gets skipped, when two users submit the same solution, so not need to worry, best of luck!

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4 years ago, # |
← Rev. 2   Vote: I like it -7 Vote: I do not like it

Well, I must acknowledge the fact that you tried very hard to point out this issue.

BUT

Codeforces is intelligent enough to detect 'Who copied from whom?'

Now consider the following solution (I am not sure if it exists or not but can surely be implemented very easily):
Say Alice gets plagiarism with Alice0 and Alice1.

With your assumption,
Submission_time(Alice) < Submission_time(Alice0) and Submission_time(Alice) < Submission_time(Alice1)
Hence, plagiarism checker will give a chance to Alice (but not to Alice0 and Alice1) to justify which he/she will for sure and will not lose any problems.
Problem solved! :)
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    4 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    what if Alice and Alice0 are in the same room again in a later contest?

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      4 years ago, # ^ |
        Vote: I like it +2 Vote: I do not like it

      In that case:

      if(Submission_time(Alice) > Submission_time(Alice0))
    // Alice is the culprit
    swap(Alice,Alice0);

// Alice0 is the culprit
plagiarism_checker(Alice,Alice0)
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4 years ago, # |
  Vote: I like it +4 Vote: I do not like it

As far as I know, the plagiarism checks and accepts the first submission of that code. If you were to copy an already AC code, you would submit later on. Everything can be checked from the submission ID. The submission that has a smaller submission ID will be considered as the actual submission, while other submissions are considered plagiarism.

Yes, just look at the submission ID. The first to submit it gets it. Since you are copying a submission, you would get a higher submission ID, thus you will be considered as plagiarism.

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

    "noo you can't just deny my plagiarizing"

    Haha submission ID go brrrr

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