Petr's blog

By Petr, 7 years ago, In English
 
 
 
 
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By Petr, 7 years ago, In English
 
 
 
 
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By Petr, 7 years ago, In English
 
 
 
 
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By Petr, 7 years ago, In English
 
 
 
 
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By Petr, 7 years ago, In English
 
 
 
 
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By Petr, 8 years ago, In English
 
 
 
 
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By Petr, 8 years ago, In English
 
 
 
 
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By Petr, 8 years ago, In English

In the discussion at http://codeforces.ru/blog/entry/6870#comment-125383 it became apparent that Jacob has submitted a solution for Round 172 Problem E that passed all system tests, and was not challenged, but in the end he didn't get the score for it because a tester has decided to stress-test it against a correct solution and add tests where it fails to the system test.

I think this is an awful, awful decision, as it goes against the spirit of progamming competitions: automatic judging and complete objectivity it gives.

There are so many ways this can discriminate against Jacob:

  • Had I submitted a solution for problem E, the tester might not suspect it would be a wrong greedy (because I'm in top 10 by rating) and would not add tests, and I'd get the points.

  • Maybe some people who opted for solving problem D instead also submitted wrong solutions, but since there were more than one of them, the testers did not think to stress-test them.

  • Had he submitted his solution right before the end of the contest, the tester might not decide to read it because he'd have other things to do.

But these points are minor compared to the main point, which I want to reiterate:

  • This breaks everyone's faith that the competition is fair and objective. The beauty and appeal of programming competitions, in my opinion, relies on this one aspect: automatic judging. Please don't take it away from us.

In this particular situation, I propose to remove the tests in question and give Jacob the score for this problem. In the future, I propose to keep to the formal procedure — use the tests prepared before the contest plus successful hacks. This is the only way to make sure the competition is not subjective.

I don't blame the particular author or tester for this problem — I actually applaud them for bringing this problem to light and explaining their actions clearly. Thanks a lot! Hopefully we can learn from this situation and avoid similar issues in the future.

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By Petr, 8 years ago, In English

I will be hosting Petr Mitrichev Contest 10 this Saturday (October 27) between 15:30 and 20:30 Moscow time (other timezones: http://timeanddate.com/worldclock/fixedtime.html?msg=Petr+Mitrichev+Contest+10&iso=20121027T1530&p1=166&ah=5 ).

The contest will be held at http://codeforces.com/gyms . Both teams and individual participants can join. The contest itself will be at http://codeforces.com/gym/100110 , but this link will be accessible only after the start of the contest.

There will be 10 problems of varying difficulty (most are quite difficult) for 5 hours. Your solution needs to be correct on all test cases to be accepted (the standard ACM ICPC rules). People will be ranked by the number of solved problems, and by total penalty time in case they're tied on solved problems, so don't be late! :) Note that in each problem you need to read the input from a file and write the output to another file — so don't read from stdin and don't write to stdout! Problem statements will be in English.

Feel free to ask any questions that you might have, and also please tell if there are any issues with the contest system — it's the first time I'm using codeforces.com/gyms .

Registration: http://codeforces.com/gymRegistration/100110

5 minutes before start, good luck everyone!

Solution ideas: http://petr-mitrichev.blogspot.com/2012/10/petr-mitrichev-contest-10-solution-ideas.html

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By Petr, 8 years ago, In English

There will be an online contest called Petr Mitrichev Contest 10. Problems are all mine, previously used in Petrozavodsk trainings for top Russian teams this September but not published elsewhere. The problems are not easy, but they are of different types and thus I hope everyone will find something interesting to solve. Both teams and individual participants can join.

I'm trying to choose the best time and place for the contest. My current proposition is: 15:30 to 20:30 Moscow time this Saturday, October 27 (in other timezones: http://timeanddate.com/worldclock/fixedtime.html?msg=Petr+Mitrichev+Contest+10&iso=20121027T1530&p1=166&ah=5 ). Looking at the contest list at http://clist.by/ and the new Yandex contest site not mentioned there (http://contest.yandex.ru/contest/ContestList.html ), all weekends are very busy, but it looks like IFMO trainings are not attended by many teams this fall and thus overlapping with it is OK.

I understand that the contest ending time in my proposition is 1:30AM in Japan and Korea and 0:30AM in China. People from Japan, Korea and China (and from Asia in general): is that too late? I'd host it earlier but there's a contest on acm.timus.ru that ends at 15:00 Moscow time that was very popular last year (http://acm.timus.ru/monitor.aspx?id=100 ), so I fear many contestants from Asia will take part there.

For the venue, I propose http://codeforces.com/gyms.

Please share your suggestions.

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By Petr, 8 years ago, In English
 
 
 
 
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By Petr, 8 years ago, In English
 
 
 
 
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By Petr, 8 years ago, In English
 
 
 
 
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By Petr, 8 years ago, In English
 
 
 
 
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By Petr, 9 years ago, In English
 
 
 
 
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By Petr, 9 years ago, In English
 
 
 
 
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By Petr, 9 years ago, In English

I've talked about a problem from today's dress rehearsal in http://petr-mitrichev.blogspot.com/2012/05/world-finals-day-2-upe-dinner.html

Here's the first tough testcase for it: http://petr-mitrichev.blogspot.com/2012/05/power-towers-problem-testcase.html

Good luck! :)

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By Petr, 9 years ago, In English
 
 
 
 
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