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Edvard's blog

By Edvard, history, 3 years ago, translation, In English,

Hello, Codeforces!

Note! The day of the contest here was wrong. Now it's fixed.

Educational Codeforces Round 12 will take place on 20 april 2016 at 18:00 MSK for the first and the second divisions.

The round will be unrated for all users and it will be held with extented ACM ICPC rules. You will have two hours to solve six problems. After that you will have one day to hack any solution you want. You will have access to copy any solution and test it locally.

If you have ideas for some problems or maybe already prepared problems that you can't use in rounds or official competitions, you can write to me.

It seems that it is harder to invent interesting simple problems (like A and B) than difficult ones. So don't be afraid to suggest interesting simple or very simple tasks (of course the difficult tasks are also needed). Please send only the problems for which you know the solution with clear statement (the story is not required). And also please add one or two samples to make the problem statement more clear.

The problemset was suggested by Codeforces users (it's time to lift this sentence inside the tegs). The problem А was suggested by user unprost. The problem B was suggested by Ayush Anand FanOfTourist. The problems C, D and E was suggested by Zi Song Yeoh zscoder. Sheikh Monir skmonir a long ago sent me a problem with difficulty C or D. I improved it by significant increase of the constraints (thanks to Mikhail Tikhomirov Endagorion who told how to solve such things). So the problem F was born.

Thanks a lot to them and all others who are sending the problems! The number of unused problems are increasing. If I didn't miss anything I already replied to all who sent me the problems at least 5-6 days ago. Please be patient if your problem was not used a long while.

The problems was prepared by me (Edvard Davtyan). Thanks to Maria Belova Delinur for checking the English statements. The problems was tested by users suggested them, respectively: unprost, Ayush Anand FanOfTourist, Zi Song Yeoh zscoder and Sheikh Monir skmonir. Thanks a lot to all of them!

I hope you will enjoy the problems! On my mind all the problems except of F is easier than usual, but F is harder.

Good luck and have fun!

Only 30 days left to the ACM ICPC World Finals!

It will be difficult to focus on the problems in such a beautiful place :-)

UPD1: The first part of the contest is finished. The open hacks will be opened in a few minutes.

UPD2: The editorial is ready for the problem F.

UPD3: The editorial is ready.

 
 
 
 
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3 years ago, # |
  Vote: I like it -15 Vote: I do not like it

Good luck and Happy Coding

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3 years ago, # |
  Vote: I like it +22 Vote: I do not like it

Good luck and enjoy the problems!

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    3 years ago, # ^ |
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    and why this getting upvotes????

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

      He is the one who contributes more than other guy.

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3 years ago, # |
  Vote: I like it +39 Vote: I do not like it

Contest is just 1.5 hour before 101 Hack, so it would be awesome if we can reschedule it 30 minutes earlier.

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3 years ago, # |
  Vote: I like it +10 Vote: I do not like it

WOW,Thailand is beautiful.

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3 years ago, # |
  Vote: I like it -20 Vote: I do not like it

any chance these edu rounds will ever be rated? something like giving half the rating of usual round ? (just an idea)

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3 years ago, # |
Rev. 2   Vote: I like it +20 Vote: I do not like it

There is something that I do not understand.

(1946 participants)

(1343 participants)

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3 years ago, # |
  Vote: I like it +3 Vote: I do not like it

Any tips for F? I found that we can reduce this problem to counting the amount of semiprimes smaller than or equal to N, plus the amount of numbers in the form p^3 (such that p is prime) smaller than or equal to N. The second part is easy to compute, but i couldn't come up with a method to get the final answer

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

When the editorial will be released?..

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    3 years ago, # ^ |
    Rev. 3   Vote: I like it 0 Vote: I do not like it

    All the problems except for the problem E is ready. E will be very soon.

    UPD: It is ready.

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3 years ago, # |
  Vote: I like it +3 Vote: I do not like it

How can I see the test case that hacked my solution?