ko_osaga's blog

Another suspicious codes from North Korea (IndiaHacks E)
By ko_osaga, history, 9 years ago, In English

These are the codes for problem E by RNS_JKS and blackEarth from last IndiaHacks contest.

http://mirror.codeforces.com/contest/653/submission/16811842

http://mirror.codeforces.com/contest/653/submission/16815024

You can easily discover the simillarities between those competitor's code. Actually, It's more hard to find the difference.

  • Struct names are different — one has "xvalue", other has "dat". but operator definition / initializators are all same.
  • Function names are different — one has "doit", other has "foo". but, inside the function, everything is same — even the indentations / spaces are same, too!
  • Several brackets / indentations are different in main function, but others are identical.

Another interesting thing is the submission from RNS_JKS one minute before AC — http://mirror.codeforces.com/contest/653/submission/16814808 This code is very different from the AC code. Then, how are these changes made in such a short time?

In usual competition, I don't go deeper to other's codes. But, when I discovered that my rating was right before IGM (2599), and reminded how I got red from 2199, I was really tempted to write this post! MikeMirzayanov, can you investigate into those issues?

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9 years ago, # |
← Rev. 2   Vote: I like it +24 Vote: I do not like it

Protip: google "codeforces north korea" and "codechef north korea". Dig from there.

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    9 years ago, # ^ |
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    yep I'm aware of those repeated cheating from North Korea. (and that's the reason why I thought they were suspicious)

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9 years ago, # |
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There is something strange with this North Koreans — http://imgur.com/a/BBQHC

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9 years ago, # |
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I think it is one user, that uses the lower rating account to make "test" submissions, so he barely get WA.

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9 years ago, # |
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Just wondering, how North Koreans manage to use internet and play codeforces?

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    9 years ago, # ^ |
    ← Rev. 2   Vote: I like it +3 Vote: I do not like it

    Some institutions are allowed internet access, and the country is really focused on achievement in competitive mathematics/computer science.

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      9 years ago, # ^ |
      ← Rev. 5   Vote: I like it -8 Vote: I do not like it

      So this institutions let them play unfairly (intentionally or because of ignorance).

      I think that it would be reasonable to block North Korea...

      Of course if the systematic foul play of this country is confirmed to be a trend.

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        9 years ago, # ^ |
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        Yep. I think they've been disqualified for cheating twice in the IMO.

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9 years ago, # |
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One of them has worse performance than you, so if they are disqualified, isn't there any chance for your rating to decrease?

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    9 years ago, # ^ |
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    No, one of them performed better than me in that contest.

    Also, even they have worse performance than me, I think it will help my rating increase since their previous rating were low.

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