Блог пользователя cgy4ever

Автор cgy4ever, история, 10 лет назад, По-английски

Hello there,

TCO2016 Online Wildcard round will start at 12:00 noon on Sept 10 EDT:

  • If you got top 10 in one of the 4 onsite regionals (and you haven't advanced to TCO onsite finals yet), then this is your last chance — top 2 will advance to onsite finals!
  • For other people, you can participate in the parallel round, it will be rated. This is open for both division, but the difficulty will be at least as hard as Div1 in SRM.

Welcome to participate and hope you can enjoy it!

Update: EvenImage and tourist are top 2 and will advance to onsite finals, congratulations!

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10 лет назад, скрыть # |
 
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What is the method to solve 500 of the parallel round?

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    10 лет назад, скрыть # ^ |
    Rev. 2  
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    We use the same tasks in both rounds, so it is also 500 in Wildcard round.

    For the number of nodes n (1 <= n <= 16) and a mask that is between 0 and 2^n-1, we can construct a graph: for i, if the i-th bit of mask is 1, then we connect node i to node 1,2,...,i-1.

    Then the number of connected subgraph in it will be very close to mask: the difference between them will be less than 16. We have 4 more nodes, use them to fix this difference.

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      10 лет назад, скрыть # ^ |
       
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      I'm having some difficulty understanding this solution. Could you please explain in a bit more detail?

      For the number of nodes n (1 <= n <= 16) and a mask that is between 0 and 2^n-1, we can construct a graph: for i, if the i-th bit of mask is 1, then we connect node i to node 1,2,...,i-1.
      How do we calculate the number of connected subgraphs for the graph constructed according to a particular mask?

      the difference between them will be less than 16.
      Why is this true?

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10 лет назад, скрыть # |
 
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I think the hard problem is much more easier than the medium one. T_T

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    10 лет назад, скрыть # ^ |
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    I tried both and medium was much easier for me. I didn't even know how to find the square root modulo in hard, while in medium I immediately know how to move towards the solution.

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      10 лет назад, скрыть # ^ |
       
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      I understand that hard can be harder for some people, but the thing is some pregained knowledge can make hard significantly easier, while it is not the case for medium (I think I haven't seen k-th root previously, but tricks with generators were no black magic for me).

      At least I would move distribution towards 300-600-900 rather than sticking to regular one.

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      10 лет назад, скрыть # ^ |
       
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      I didn't even know how to find the square root modulo in hard

      What would you even need that for? (That was what I thought about first, but since sqrt doesn't solve odd k, I scrapped it and tried primitive roots next. It worked. I also find 1000 about as easy as 500.)

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    10 лет назад, скрыть # ^ |
     
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    Yes, Hard looks overwhelming but the solution itself is pretty simple. Somehow most people opened Medium instead of Hard, so at least it is a fair game.

    Btw, congratulations!

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10 лет назад, скрыть # |
 
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Got TLE on hard, added "unordered_" and it passed in practice room ;__;. Missed such a chance of defeating all guys in official round :(.

Btw, TopCoder achieves a new level of quality in number of participants :P.