adamant's blog

Invitation to CodeChef October Lunchtime 2017!
By adamant, 7 years ago, translation, In English

Hello CodeForces Community!

The clock is ticking and Chef is ready with Lunchtime meal of October. So get ready to knuckle down October Lunchtime and mark your calendars for below. Joining me on the problem setting panel, we have:

  • Problem Setter: chemthan (Trung Nguyen)
  • Problem Tester & Editorialist: adamant (Alexander Kulkov)
  • Contest Admin: kingofnumbers (Hasan Jaddouh)
  • Russian Translator: CherryTree (Sergey Kulik)
  • Mandarin Translator: huzecong (Hu Zecong)
  • Vietnamese Translator: Team VNOI

I hope you will enjoy solving them. Please give your feedback on the problem set in the comments below after the contest.

So, note down the details and be there when the contest starts:

Time: 28th October 2017 (1930 hrs) to (2230 hrs). (Indian Standard Time — +5:30 GMT) — Check your timezone.

Details: https://www.codechef.com/LTIME53

Registration: You just need to have a CodeChef handle to participate. For all those, who are interested and do not have a CodeChef handle, are requested to register in order to participate.

Prizes: * Top 10 performers in Global and Indian category will get CodeChef laddus, with which the winners can claim cool CodeChef goodies. Know more here: https://www.codechef.com/laddu. (For those who have not yet got their previous winning, please send an email to winners@codechef.com)

Good Luck! Hope to see you participating!!

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7 years ago, # |
  Vote: I like it +44 Vote: I do not like it

Less than two hours is remaining to start! There will be challenging problems for very skilled participants!

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7 years ago, # |
← Rev. 2   Vote: I like it +6 Vote: I do not like it

How to solve problem "Optimal Subset" ?

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

My O(T * n * n) solution for MAXNUM3 passed)

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    7 years ago, # ^ |
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    Can you please explain your solution?

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

      I don't even know what to explain here.
      I just try to delete each position, and do it for each position in O(n).

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

How to solve weird competition?

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

weird competition! Everyone piled on the first two problems xD Btw please provide an editorial on the weird competition problem. That problem was really interesting(and I don't want my 2 hours to go in vain :P)

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

    Come on is that too much too ask for :( Anyway can someone please help me get to the solution? Here's my little 'progress' in those two hours:
    Suppose, we have two players A and B winning a and b games, respectively, where a ≤ b. Now if we fix a + b but replace a with a-x and b with b + x, then a and b becomes more unequal and their squared sum increases. Here's the proof: (a-x)^2 + (b+x)^2 = a^2 + b^2 + x*(2b+x-2a) > a^2 + b^2
    Now, every player wins an integer number of games between 0 to n-1. To make their squared sum largest, we should make them as much unequal as possible i.e. i'th player should win i-1 games(Otherwise, if A and B wins equal number of games, then reverse the result of the AB game and the sum would increase)
    Now, if this greatest sum is less then k, then it's impossible to get the sum to be equal to k. Otherwise, my thought was to pull closer two of the players at each step and thus decrease the sum until we reach k. But I'm not yet sure how to know which two players to select and how do I even construct the tournament in the end knowing total wins for each player :(

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

Can somebody please tell me why my solution for Buggy Calculator got WA for subtask 2 ? Here is my solution : https://www.codechef.com/viewsolution/15981484

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

How to solve the third and the fourth problem ?

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

Have people received the laddoos who came in top 10 in India in October Lunchtime?

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