cristian1997's blog

FIICode Final Round [CSAcademy online mirror — rated]
By cristian1997, history, 4 years ago, In English

The FIICode Final Round will take place Saturday, 29th August, from 13:05 to 15:35 (UTC).

The problems were created and prepared by bicsi, Juve45, cristian1997, denis2111, Fanurie and pauldiac. We would also want to thank sebi110 and lungualex00 for testing the round and providing valuable feedback.

We will host a parallel online mirror on CSAcademy at 13:05 (UTC). We invite everyone to join. The mirror round will be rated :)

This is the link of the mirror.

LE: The contest finalists have been automatically added to the official round. (Which is by default hidden for the rest).

You can check the list of finalists here

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4 years ago, # |
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So CSAcademy will be back making rated rounds???

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    4 years ago, # ^ |
      Vote: I like it +21 Vote: I do not like it

    no ... it's just the FIICode finale, hosted by csacademy..

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

The contest will contain 6 tasks, and the difficulty should be somewhere between a CF Div1 and CF Div 2. We strongly advise you to read all the problems :).

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4 years ago, # |
  Vote: I like it +85 Vote: I do not like it

Please rename CsAcademy to FllCode finally

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4 years ago, # |
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Auto comment: topic has been updated by cristian1997 (previous revision, new revision, compare).

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4 years ago, # |
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Update: The contest starts in ~6 hours

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4 years ago, # |
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what is a mirror contest?

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    4 years ago, # ^ |
    ← Rev. 2   Vote: I like it +18 Vote: I do not like it

    there's an official final round, for those who qualified to it. normally it is onsite but now it will only be online due to travel restrictions.

    the mirror is the same contest but open to any user to practice

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4 years ago, # |
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Reminder: The contest start in ~2 hours. Good luck to everyone!

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4 years ago, # |
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Auto comment: topic has been updated by cristian1997 (previous revision, new revision, compare).

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4 years ago, # |
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problem Mountain Time is similar to problem Baltic 12-Peaks

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

We would gladly like to hear your feedback about the problems. We are going to publish editorials in a short time. Some personal thoughts:

  • we didn't have an $$$O(N)$$$ solution to the fifth problem (after building the tree), and it seems that most of the people who solved it had a different solution; care to share it?

  • I'm pretty surprised that solutions with sqrt decomposition passed for the sixth problem :)

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

    I haven't read problem F, so I will not say anything about it.

    A. Nice, easy, easy to implement.

    B. Ok problem. After the observation that N must be small it is very standard. I don't really like this kind of "tricky, single observation" problems, but this was ok.

    C. A bit boring problem. The implementation was, for me, much harder than the thinking part.

    D. I already knew this one (or something very similar). It is an ok problem, but not very original (in the sense that it is immediately clear that some kind of dsu-approach will solve it).

    E. I liked this one a lot. It was a very cool problem! My solution is $$$O(N\log(N))$$$ or $$$O(N\log(N)^2)$$$ or something like this (so I guess it is similar to the "official one"). My solution, for each subtree, computes the nim values of the subtree after a single move is done in the subtree (so, for each subtree, it computes a list of many nim-values).

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      4 years ago, # ^ |
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      I think I understand it, now that I look at it again. Thanks for the feedback!

      Our solution is quite different, actually. It uses the fact that the tree you build can't have big heights, so you can compute the Sprague-Grundy value of a node via brute force.

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4 years ago, # |
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what is the solution of Mountain Time ? I try pbs but it got TLE on test 5

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    4 years ago, # ^ |
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    Check https://csacademy.com/contest/archive/task/mountain-time/solution/

    TL;DR: Sort cells decreasingly by height, use DSU that keeps track of maximum height, merge lists of cells with maximum by using linked lists (small-to-large merge might still work).

    I didn't prepare this problem in particular, but I was somehow expecting solutions with parallel binary search and DSU to be hard (if not impossible) to squeeze through, because of the $$$O(N \cdot log(N) \cdot log^*(N))$$$ complexity, with a considerably high constant factor.

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

Are standings of the official final round available?

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