Pand9's blog

There was a bug in CF433 div2 C during contest. My solution (identical) passed tests submitted today.
By Pand9, history, 7 years ago, In English

There was a bug in CF433 div2 C during contest, my solution (identical) passed tests submitted today. I just want somebody to know, so that bugs like this won't happen in the future. My submission: http://codeforces.net/contest/879/submission/31755726 Accepted submission with the same code: http://codeforces.net/contest/879/submission/32008085 Should I report/mail it to somebody maybe? I don't know who's responsible for things like this. Thanks.

  • Vote: I like it
  • +11
  • Vote: I do not like it

»
7 years ago, # |
  Vote: I like it 0 Vote: I do not like it

I had faced a similar situation in previous round,I don't know what it means but it sure wasted a lot of my time.If I am wrong please point out.

Link

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

    Your codes are different. You made changes, so why are you complaining? Output was not the same as expected.

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

It is really bug, because last "\n" of an output is optional.

And Codeforces' COMPARE function don't show any difference comparing two versions.

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

    I just realized I'm writing spaces at the end of every line (my helper function does that). It's implied, but not really specified, that whitespaces are ignored in the output, right? So, maybe, it's partially my fault.

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

      Spaces are not allowed, but one newline (the only of all whitespaces) at the end of an output should be optional. I haven't seen any changes with Codeforces' COMPARE function, your both submissions seem identical.

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

        I think it might not use standard COMPARE function, because there's many correct solutions. Thanks for the info that spaces are not allowed, I will remember in the future.

        → Reply
      • »
        »
        »
        »
        7 years ago, # ^ |
          Vote: I like it +1 Vote: I do not like it

        Oh, you mean COMPARE for source codes. Sorry for confusion.

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

There was an announcement in Div1 contest:

Checker incorrectly handled whitespace characters, it is fixed now, affected solutions are rejudged.

You can see it if you enter Div1 contest page. However, I don't see such an announcement for Div2.

→ Reply