kostya_by's blog

April Cook-off 2015 on CodeChef
By kostya_by, 9 years ago, In English

Hi everybody!

I'm inviting you to take part in the April Cook-off 2015 on CodeChef at http://www.codechef.com/COOK57. The problems are prepared by me this time.

Time: 19rd April 2015 (2130 hrs) to 20th April 2015 (0000 hrs). (Indian Standard Time — +5:30 GMT) — Check your timezone.

Details: http://www.codechef.com/COOK57

Registration: Just need to have a CodeChef user id to participate.

New users please register here

I would also like to thank all guys that were taking part in preparations of this contest:

Good luck!

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

Comments Comments (26)
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9 years ago, # |
  Vote: I like it +5 Vote: I do not like it

Hey its starts now

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9 years ago, # |
← Rev. 3   Vote: I like it +70 Vote: I do not like it

Huh, there are 0 problems in the contest. That was easy :D

And occasional errors 502 and 503.

UPD: The problems seem to be there.

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

    Reminds me of this but with 0 problems (the ones we're supposed to solve).

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9 years ago, # |
  Vote: I like it +14 Vote: I do not like it

502 Bad Gateway

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

Every time they are having issues at the start of the contest. That's bad....

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    9 years ago, # ^ |
      Vote: I like it +40 Vote: I do not like it

    I thought they said that they resolved issues and improved system a lot; didn't they wrote about it after January Cook-off fail?.. And both February and March Cook-offs started relatively well... But now old CodeChef is back :)

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9 years ago, # |
  Vote: I like it +32 Vote: I do not like it

Now mom asking me to go and wash dishes instead of waiting for problem to appears

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    9 years ago, # ^ |
      Vote: I like it +19 Vote: I do not like it

    I've just washed dishes too. Still no problems.

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      9 years ago, # ^ |
      ← Rev. 2   Vote: I like it +4 Vote: I do not like it

      But at least no dirty dishes, either :D

      There they are now! (of course, there are still countless failed requests)

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9 years ago, # |
  Vote: I like it +9 Vote: I do not like it

Only the count-down timer is working perfectly

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

UPDATE : Codechef is back . I can see the problems

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

We are trying to get the site back. Apologies for the inconvenience. Request you all to wait for some time.

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9 years ago, # |
  Vote: I like it +18 Vote: I do not like it

It seems the scoreboard is broken... the suspense is killing me!

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

How to solve LFIVE faster than O(n^2logn+q)? And is there anybody who solved it with this complexety? Thank you!

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

    I solved it with that complexity: http://ideone.com/j7Ee34.

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

    I solved it with this, too; after failing to optimize my O(QN) solution.

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

      There was a way to optimize an O(N^2 + NQ) approach so it would get an AC. The key point is to use memory cache efficiently: multiplying two rows of a 2D matrix is five times faster than multiplying a row and a column of the same matrix.

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        9 years ago, # ^ |
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        So you create a transposed copy of the original matrix and then multiply the rows of these two matrices, or is there another way?

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

          No, that's pretty much what you should do if you want to multiply a row and a column of one matrix in general case. Talking of this problem, you could store only one matrix just by making f[j][i] equal to f[i][j] (i < j).

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      9 years ago, # ^ |
      ← Rev. 2   Vote: I like it 0 Vote: I do not like it

      I have both O(N^2 log N + NQ) with efficient using of memcache and O(N^2 log N + Q) solutions and they run pretty much the same time.

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

I think solving the last problem(AGENTS) in python is quite easy : I have figured out the general equation(#)
And I know that there is a module available to solve system of linear equations. And so I directly used that, Here is my solution : http://www.codechef.com/viewsolution/6799925

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

    To be honest, I didn't consider such an approach in Python while preparing the contest. But it's nice if you got an accepted with it since the main idea of the problem was not to solve a system of linear equations but to build that system.

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

      Yes, developing the system is nice. It remembered me about my 12th class where we used to do lot of problems in integration. And I am excited that this is my first contest in which I have done hardest problem and ofcourse 3 problems.

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