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galen_colin's blog

Invalid hacks in Codeforces Round 697
By galen_colin, 4 years ago, In English

upd: has been fixed now

This seems like a problem. On problem A, the statement guarantees $$$2 \leq n \leq 10^{14}$$$, but the validator accepts $$$n = 1$$$, causing an invalid edge case for many solutions.

For example, this hack should not work. The input is just:

1
1

pinging {Supermagzzz, Stepavly, MikeMirzayanov}

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4 years ago, # |
  Vote: I like it +28 Vote: I do not like it

It should be fixed, but the round is already unrated so IMO it doesn't affect much.

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4 years ago, # |
  Vote: I like it +11 Vote: I do not like it

This doesn't affect the point of this blog, but as a side note, it seems strange that the statement doesn't allow $$$n = 1$$$ in the first place.

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4 years ago, # |
  Vote: I like it +9 Vote: I do not like it

It's a big mistake, I'll wix it. Thanks for the issue.

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