Iceberg's blog

Invitation to Winter Cup 6 Online Mirror (ICPC Rules, Teams Preferred)
By Iceberg, 2 years ago, In English

Hello CodeForces Community,

We are happy to invite you to participate in Winter Cup 6.0 Online Mirror Contest. The mirror is scheduled to take place on Codeforces at Mar/03/2024 16:30 (Moscow time) and will last for 5 hours.

Winter Cup is a prestigious annual competitive programming contest held by ACM, INSAT Student Chapter. It unites Tunisia's brightest minds in a thrilling display of skill and innovation. Widely regarded as the nation's best competition, aside from the official ICPC regional contest.

The contest consists of 15 problems created and prepared by Iceberg, OussamaJB and ramizouari with difficulties from div2A to div1D.

We would like to thank :

Enjoy solving !

You can find here links to Winter Cup 4 and Winter Cup 5

UPD : Editorial

  • Vote: I like it
  • +35
  • Vote: I do not like it

Comments Comments (17)
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2 years ago, hide # |
← Rev. 2  
Vote: I like it +12 Vote: I do not like it

Good Luck in the Contest !

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2 years ago, hide # |
 
Vote: I like it +12 Vote: I do not like it

Good luck to the participants, I hope you enjoy the problemset !

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2 years ago, hide # |
 
Vote: I like it +15 Vote: I do not like it

Good Luck Guys. Hope you enjoy the problemset. Give us your feedback later!

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

As a tester I really enjoyed this year problemset! GJ guys!

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

Good luck to the participants ! As a tester I enjoyed the problems!

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

Is there any editorial?

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

I feel no. of participants in round do not justify the problem quality. Every problem had something unique and interesting.

Thanks to the authors really enjoyed the Problemset. Kudos.

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    2 years ago, hide # ^ |
     
    Vote: I like it +3 Vote: I do not like it

    CAn you share your approach for problem F find the tree?

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      2 years ago, hide # ^ |
       
      Vote: I like it +3 Vote: I do not like it

      This problem requires observation, Try to build a tree with some property and you will get the answer.

      First we have to take care of $$$v_i = i$$$ then we cannot construct tree.

      Now if our $$$ N = 2$$$ we will always have a tree. Given in sample case.

      For $$$ N \gt 2 $$$ if we have all nodes from $$$1, 2, ..., N$$$ in the $$$v$$$ array, tree cannot be formed. Because we cannot have all the nodes which are leaves.

      Now consider if a node is not present in the tree, you will always construct a Star Tree with this node in centre. So answer is Yes.

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    2 years ago, hide # ^ |
     
    Vote: I like it +3 Vote: I do not like it

    Thank you for your comment, we were really happy reading your feedback. I also wanted to say that we just released the editorial.

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2 years ago, hide # |
 
Vote: I like it +3 Vote: I do not like it

Any hints for L2

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    2 years ago, hide # ^ |
     
    Vote: I like it +6 Vote: I do not like it

    if we find an index $$$j$$$ such that $$$a_j$$$ is a prime > $$$n/2$$$

    then for each $$$i \neq j$$$ ;$$$ \ lcm(a_i , a_j) = a_i \cdot a_j $$$ ; (so we can guess the whole array)

    because $$$a_i$$$ can't be equal to $$$a_j \cdot q$$$ where $$$q \gt 1$$$ otherwise it will exceed $$$n/2$$$.

    And we have $$$ m \approx \frac{n}{ln(n)} - \frac{\frac{n}{2}}{ln(\frac{n}{2})} $$$ primes > $$$n/2$$$

    $$$m/n \gt 1/30$$$ so we can use randomization.

    try 100 indices and check if one of them is prime $$$ \gt n/2$$$

    and then we can guess the whole array.

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