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Educational Codeforces Round 15
By fcspartakm, history, 8 years ago, translation, In English

Hello, Codeforces!

Educational Codeforces Round 15 will take place on 29 July 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.

We with Mike MikeMirzayanov Mirzayanov decided to prepare this Round, because Edvard Edvard Davtyan is very busy at his new job. Good luck and have fun!

UPD Competition completed! Thank you all! Editorial

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8 years ago, # |
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Auto comment: topic has been translated by fcspartakm (original revision, translated revision, compare)

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8 years ago, # |
  Vote: I like it -30 Vote: I do not like it

This is unrated for all user meant?

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8 years ago, # |
  Vote: I like it -41 Vote: I do not like it

Where is Edvard ?

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    8 years ago, # ^ |
      Vote: I like it +29 Vote: I do not like it

    "because Edvard Edvard Davtyan is very busy at his new job"

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    8 years ago, # ^ |
      Vote: I like it +15 Vote: I do not like it

    In the mountains.

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8 years ago, # |
← Rev. 2   Vote: I like it -37 Vote: I do not like it

CF contest no 702. If we truncate trailing even digits, we would get lucky 7!

Hope everyone get points multiple of 702!

(Do not see rev 1, it was a mistake!)

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    8 years ago, # ^ |
      Vote: I like it +35 Vote: I do not like it

    It is number 702.

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

      Ow! You are seeing too old version, see the updated revision!

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8 years ago, # |
  Vote: I like it -14 Vote: I do not like it

hello

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8 years ago, # |
  Vote: I like it -14 Vote: I do not like it

in B in the first example shouldn't the pairs of indices included in answer be: (1, 4) and (2, 4) instead of (1, 4) and (3, 4)?

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8 years ago, # |
  Vote: I like it +6 Vote: I do not like it

Will we be able to see the tests before hacking period ends?

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8 years ago, # |
  Vote: I like it +20 Vote: I do not like it

Well, i found out that my first submission is incorrect, so i resubmited but its still showing the first submission

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    8 years ago, # ^ |
      Vote: I like it +1 Vote: I do not like it

    and it shows hack it for both submission too .. i wonder what happen if someone got successful hack on the old one

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

Has anyone tried solving D using a binary search?

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

How is it my solution for D with map runs in 200 ms but solution with multiset gets TLE (>3000 ms)?

multiset: 19483894

map: 19499476

Is multiset really so slow? Why?

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8 years ago, # |
  Vote: I like it -26 Vote: I do not like it

I downvoted every single comments:D

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

Got "unexpected verdict" in hack 245453, 245473 and 245477.

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8 years ago, # |
  Vote: I like it +5 Vote: I do not like it

How to solve problem C if all the points were on 2 dimensional plane?

With k-d trees a straightforward is possible, is there another/better solution?

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

Hi,
In this this round, I've tried to hack the others code in hacking phase; but I couldn't find any buggy code or some tricky test case to hack and I've finished with an unsuccessful hacking attempt! After this try, I noticed that I should have a suitable mechanism for hacking. So what's your idea about it? what's your suggestion for me to do better in hacking phase?
And here my questions about hacking:

  1. How should I choose someone to hack? Randomly from common standing or needs some logical decision?
  2. When's the right time to hack in normal rounds?
  3. What's the right procedure to hack? Read codes and then break it with a test case or just check every code with some already prepared tricky test cases?
  4. How should I make test cases? According to someone code, generate randomly or make by hand after thinking about the problem?
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    8 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    I would also like if someone replies on this.

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

      This is a good question! I've faced to this event and It's my question too. So I'm waiting for the answer...

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

any hint about problem E or link please !!

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

problem E hint please

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

Why for the first testcase the output is 3 not 4 The increasing sequence can be 1 2 11 15 or 1 7 11 15

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