kostka's blog

By kostka, 3 months ago, In English,

The Central European Olympiad in Informatics (CEOI) is an annual informatics competition for secondary school students for central European countries. The 25th CEOI takes place in Warsaw, the capital of Poland.

This year, 13 countries will participate in the CEOI: Austria, Azerbaijan, Croatia, Czechia, Georgia, Germany, Hungary, Italy, Romania, Slovakia, Slovenia, Switzerland, and Poland. The full list of participants is available at: https://ceoi2018.pl/teams/

There will be two competition days: 8/14 and 8/16 (Tuesday and Thursday). We invite everyone to participate in the online mirror, hosted by the CS Academy (details). The contest will start both days one hour after the end of the onsite competition (at 13:00 UTC) and last 5 hours (till 18:00 UTC).

Further info can be found on the official website of the competition: https://ceoi2018.pl/ and our Facebook fanpage: https://facebook.com/ceoi2018/.

 
 
 
 
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3 months ago, # |
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The first day of the competition has started. The scoreboard is available at https://ceoi2018.pl/liveranking/

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    3 months ago, # ^ |
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    Sorry, how to separate points of each problem? Why there is 5 columns and what they show us?

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      3 months ago, # ^ |
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      The first two problems (car and dis) were used during the trial session.

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Tasks, testdata and the presentation of day 1 solutions can be found at https://ceoi2018.pl/tasks/

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3 months ago, # |
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The second day has started. The scoreboard is available at https://ceoi2018.pl/liveranking/

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3 months ago, # |
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day 2 update: You can participate in the online mirror for the second day. It will start in 4 hours. (1 hour after the onsite contest ends)

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3 months ago, # |
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Is there an efficient way to generate multiplicative partitions of a number? Could be used to solve Toys Small.

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3 months ago, # |
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Statements, test data and some details about solutions have been published: https://ceoi2018.pl/tasks/

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    3 months ago, # ^ |
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    The analysis of Toys seems to be missing from the Day 2 Presentation slides. Can you please add that?

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      3 months ago, # ^ |
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      Unfortunately, there were no slides for this problem.

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      3 months ago, # ^ |
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      Write a recursive function void rec(n, sum) that iterates over divisors d of n and runs recursively rec(n/d, sum+d-1). That's too slow, so we must memoize states (n,sum) not to enter them twice, and also memoize divisors in a map<int, vector<int>> not to recompute that in each time.

      Alternative approach: think about it as DP and for every encountered n (starting either from 1 or from the initial given n) have a set with possible sums. Also, when going to from n to n / d you can pass divisors of n and remove those that don't divide n / d, because the set of divisors of n / d is a subset of the set of divisors of n.

      And yeah, slides were only for FIB to avoid a lot of writing on the blackboard, and then the projector didn't work ;_;

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    3 months ago, # ^ |
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    The input file format in Triangles test data is quite cryptic, could you explain that — or publish the grader program used in the contest :)

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3 months ago, # |
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You can solve all problems here: https://oj.uz/problems/source/358 We set the time limits as same as CSAcademy's.