SecondThread's blog

By SecondThread, history, 3 months ago, In English

Problem D of Codeforces Round #224 has incorrectly rendered samples for me. (Chrome on Mac). There are curly braces in the output for samples 2, 4, and 5. These are not in the actual data, they are just on the website.

Here is the second sample:

3 4
####
#>^{}#
####

The curly braces are not supposed to be there. I know there have since been updates to how samples are rendered (showing different backgrounds for adjacent test cases within the same sample, for example), so I suspect this may have broken in one of those updates.

Not sure where to post this, so thought I'd flag it here.

  • Vote: I like it
  • +28
  • Vote: I do not like it

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3 months ago, # |
  Vote: I like it +15 Vote: I do not like it

It probably doesn't have anything to do with your own system, I have the same bug on Windows 10 Chrome, Firefox and Edge.

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3 months ago, # |
  Vote: I like it +10 Vote: I do not like it

same on Linux Chromium

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3 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Reproduced in Windows 11 Firefox, I think the characters used in the sample might have triggered some escape mechanisms at the backend.

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3 months ago, # |
Rev. 2   Vote: I like it +2 Vote: I do not like it

Thank you. It appears that the issue was not the result of https://codeforces.com/blog/entry/105779 However, it can be seen here https://web.archive.org/web/20210416021306/http://codeforces.com:80/contest/382/problem/D

Thus, the incorrect rendering has been occurring for at least three years.

The most challenging aspect of addressing such bugs isn't the backend repair but ensuring backward compatibility. Fixing this might impact other problems that depend on the current behavior.

A probably better solution would be to correct such issues in Polygon.

Do you know of any other incidents involving similar problems?