awoo's blog

About the issue of Educational Codeforces Round 73
By awoo, history, 5 years ago, In English

First of all, I'm really sorry for the issues the round had. We paid not enough attention to make sure everything works as intented and got punished for it. That was a lesson for us, we'll do our best to keep the future rounds as clean as possible.

The problem B had an issue with the checker, solutions have been recieving wrong verdicts. Unfortunately, neither its author, nor reviewers have noticed the bug.

Can you spot it without looking in comments?

The bugged checker

It's been compiling with no warnings even with -Wall -Wextra -Wconversion flags. By no means that justifies our carelessness but the mistake was really unfortunate.

We really hope you enjoyed the problems nevertheless.

The contest will definitely be unrated for the participants affected by it.

  • Vote: I like it
  • +151
  • Vote: I do not like it

Comments Comments (16)
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5 years ago, # |
  Vote: I like it +67 Vote: I do not like it
The error
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5 years ago, # |
  Vote: I like it 0 Vote: I do not like it

bool -> int

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5 years ago, # |
  Vote: I like it -31 Vote: I do not like it

That is why Java is Love!!!

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5 years ago, # |
  Vote: I like it +31 Vote: I do not like it

Is it rated for the rest? If so it is a good solution to the situation. Thanks for the round and for the clarification

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5 years ago, # |
  Vote: I like it +165 Vote: I do not like it

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

    Yes, I also submitted to check my solution is correct or not. Because WA on test1 doesn't give penalty but when I submit it, it shows AC.

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5 years ago, # |
  Vote: I like it +46 Vote: I do not like it

If you use {} instead of = to initialize your variables, you will get a warning.

Example
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    5 years ago, # ^ |
    ← Rev. 3   Vote: I like it +20 Vote: I do not like it

    ... and also you will switch from copy-initialization to direct-initialization so any explicit conversion will be acceptable.

    ... and also you will have a potential aggregate-initialization of the first struct member leaving other uninitialized.

    ... and also you will potentially have an initialization via initializer-list if it is defined for the target type as it is preferred during the overload resolution.

    The right answer is:

    spoiler
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5 years ago, # |
  Vote: I like it +31 Vote: I do not like it

Next time don’t ignore polygon’s warning and do some checker test as well))). I always try some tests to receive all possible verdicts. It really helps. Btw round was awesome)

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

Does this mean that people who pass B will get more rate? It doesn't seem fair.

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5 years ago, # |
  Vote: I like it +42 Vote: I do not like it

Checker for a Checker will now be a thing.

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5 years ago, # |
  Vote: I like it +70 Vote: I do not like it

If you tested any wrong solutions whose output is valid, not the best, and the number of duels is not zero, e.g. a solution which put a black or white knight in each cell randomly, you should have found the mistake.

Maybe it's not so easy to find the mistake by eyes, but it seems that no one tested any wrong solutions before the contest.

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5 years ago, # |
← Rev. 2   Vote: I like it +30 Vote: I do not like it

And I have just checked the problem revision, it was 4 when the contest began, and now it's 12. (see the submissions at the begin of the contest and at present, see the number in the block "problem" after "1221B — ")

I'm just wondering how to finish a problem in 4 revisions.

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5 years ago, # |
  Vote: I like it +1 Vote: I do not like it

The checker program was more naive than my submitted code for B. I am glad that we both are stupids.

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

In my case, first I submitted the wrong solution but after some thinking I submitted the correct solution during the contest. So, can't my judgement be done based on the correct submission

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5 years ago, # |
  Vote: I like it +167 Vote: I do not like it

Lol. This was educational.

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