DBradac's blog

By DBradac, history, 3 years ago, In English,

I would like to invite you to participate in the online mirror of the Croatian Olympiad in Informatics which is held this Saturday.

The problemset will consist of 3-5 IOI stlye tasks and you will have 5 hours to solve them. The expected difficulty is greater than usual COCI rounds, but lesser than IOI.

Click here to see where the coding begins in your timezone.

 
 
 
 
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3 years ago, # |
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I see new backup menu in evaluator. What is that for?

Thanks in advance :)

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    3 years ago, # ^ |
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    You can backup files on the judge if you are afraid you will accidentally erase them loacally or something. As far as I know, nobody really uses it.

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3 years ago, # |
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It tell's me that I am not allowed to log in from this location. Can anyone help me?

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    3 years ago, # ^ |
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    You should select "Croatian Olympiad in Informatics" in the dropdown menu.

    This is a problem in every Croatian contest, so maybe the organizers could fix this?

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3 years ago, # |
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Will there be an immediate feedback like in IOI?

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    3 years ago, # ^ |
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    yes

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      3 years ago, # ^ |
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      Nice! If I remember correctly, last year there was no feedback during the contest

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        3 years ago, # ^ |
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        Unfortunately, there is no full feedback :(

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      3 years ago, # ^ |
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      sorry, I was wrong, there is no full feedback

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3 years ago, # |
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Start delayed by 15 minutes?

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3 years ago, # |
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.

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3 years ago, # |
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There actually isn't real feedback. The system just says whether we have passed the samples or not.

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3 years ago, # |
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Really nice contest.

How to solve 3 and 2?
On 1 is O(N * M) the intended solution?
On 4 is with centroid decomposition intended to pass for 100?

Also when will results be available?

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    3 years ago, # ^ |
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    How did you solve 1?

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    3 years ago, # ^ |
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    I solved 4 for 40 points. Suffix array + LCP for chain, dfs O(n2) for n ≤ 1000.

    How to solve for 100?

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    3 years ago, # ^ |
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    2) Divide and Conquer

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      3 years ago, # ^ |
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      wow the solution comes really easy when someone tells you to think about divide and conquer :/

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        3 years ago, # ^ |
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        But you need to carefully handle case when "middle row" components are connected in upper and bottom part simultaneously

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3 years ago, # |
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When will there be results?

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3 years ago, # |
Rev. 5   Vote: I like it +43 Vote: I do not like it

Solution sketch + 100p Codes

Problem 1
Problem 2
Problem 3
Problem 4

For p3, constant factor was not a problem. (worst tc in 0.05s) I fixed one typo (y -> y + 1) and got 100 points. So sad to miss 400p

Sad news : Problem 4 was already posed at JAG contest. (http://jag2015spring.contest.atcoder.jp/tasks/icpc2015spring_a)

Still, the problems were really interesting. I really enjoyed solving it. Thanks for the great effort!