P___'s blog

By P___, history, 5 weeks ago, In English,

Hi,

Since nobody has mentioned this SRM, I do that here:

Time.

I am not the author, just want to increase the number of participants.

Thanks!

 
 
 
 
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5 weeks ago, # |
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Can anyone tell me what can be done when the applet says "A connection to the server cannot be established" when I try to login? I tried autodetect, it doesn't work. It was working well a few weeks back.

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5 weeks ago, # |
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Thank you so much for posting this! I always miss SRMs, and finally get to compete in one. GLHF everyone!

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5 weeks ago, # |
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Does anyone have proved solution for 1000?

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5 weeks ago, # |
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How to solve medium? (I have O(k3) with small constant which gets AC in 1.6s)

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    5 weeks ago, # ^ |
    Rev. 5   Vote: I like it +21 Vote: I do not like it

    upi is an expected sum of heights of nodes in tree with i nodes.

    dpi is an expected sum of length of paths in tree with i nodes.

    by linearity of expectation.

    Similary, because sum of length is sum of length in both subtrees and sum of length of paths going through root.

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5 weeks ago, # |
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About Div1 Hard.

My solution was to look at only Pareto-optimal choices. First, we sort the friends by decreasing number of bits set. After that, we recursively pick or kick them in that order. The single important check which makes it run faster than like 2568 is as follows: if we kick a friend X, we also have to kick all further friends which have a subset of X's skills (otherwise, the choice wouldn't be Pareto-optimal).

In practice run, this takes <100ms on all the given tests. Can someone please either construct a test where this becomes slow, or prove a reasonable asymptotic bound for the number of Pareto-optimal choices?

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    5 weeks ago, # ^ |
    Rev. 3   Vote: I like it +13 Vote: I do not like it

    What about all (C(8, 4)) masks with 4 bits? Then it will be like 708?

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      5 weeks ago, # ^ |
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      Challenge succeeded :) .

      A pity you were not in my room.

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        5 weeks ago, # ^ |
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        I wanted to challenge you with this exact test..

        However, I was so stupid that I did not know paste in TC is ctrl+v (while in macOS is it command + v). :P

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    5 weeks ago, # ^ |
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    On all vectors with 4 1-bits out of 8 it will be 708 / 8! ≈ 1010

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5 weeks ago, # |
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can someone explain how to solve "div1 easy"? making second tree by removing edge from first tree.

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5 weeks ago, # |
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how to solve div2b