simonlindholm's blog

EGOI 2024 results and problems
By simonlindholm, history, 3 months ago, In English

logo

The European Girls' Olympiad in Informatics 2024 took place from 21st to 27th of July in Veldhoven, the Netherlands. The results can be found here. Huge congratulations prvocislo for winning the contest for the second year in a row and all other contestants who did incredibly well.

The tasks were authored by jasmin_studer, zoooma13, Sorting, bestial-42-centroids, nigus and Massimo Cairo.

The problem were prepared by the scientific committee consisting of nigus, simonlindholm, Xylofo, zehnsechs, SlavicG, flute42 and JanKuipers.

We also thank our testers: Petr, carolinux, Ante0417, mango_lassi, ainta, jasmin_studer and waynetuinfor.

An online mirror is available with flexible start time on Kattis running until July 29. The problems can also be found individually on Kattis (/Open Kattis) or on the EGOI24 website.

Test data and jury solutions are available at https://github.com/zehnsechs/egoi-2024-testdata.

You are welcome to discuss the problems in the comments!

  • Vote: I like it
  • +289
  • Vote: I do not like it

»
3 months ago, # |
  Vote: I like it +19 Vote: I do not like it

orz

→ Reply
»
3 months ago, # |
  Vote: I like it -170 Vote: I do not like it

Cant wait to see all trans teams if they are allowed.

→ Reply
»
3 months ago, # |
  Vote: I like it +63 Vote: I do not like it

prvocislo orz

→ Reply
»
3 months ago, # |
  Vote: I like it +121 Vote: I do not like it

berr orz

→ Reply
»
3 months ago, # |
  Vote: I like it -20 Vote: I do not like it

Veeon orz

→ Reply
»
3 months ago, # |
  Vote: I like it -25 Vote: I do not like it

stanirina ORZ!

→ Reply
»
3 months ago, # |
  Vote: I like it +3 Vote: I do not like it

simona1230 orz

→ Reply
»
3 months ago, # |
  Vote: I like it -6 Vote: I do not like it

rahidilbayramli orz

→ Reply
»
3 months ago, # |
  Vote: I like it +13 Vote: I do not like it

The problems can also be found individually on Kattis or on the EGOI24 website.

how does one submit without joining the mirror?

→ Reply
»
3 months ago, # |
  Vote: I like it +98 Vote: I do not like it

I didn't know it's possible to add gifs to blog posts but this one is awesome!

→ Reply
»
3 months ago, # |
  Vote: I like it +1 Vote: I do not like it

AtinaRu kicika orz

→ Reply
»
3 months ago, # |
  Vote: I like it +3 Vote: I do not like it

CS50programmer rahidilbayramli orz

→ Reply
»
3 months ago, # |
  Vote: I like it +25 Vote: I do not like it

clarinha ORZ top 4 with 4 attemps left

→ Reply
  • »
    »
    3 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    wow thats insanely cracked! good luck in her future attempts, it'll be cool to see the improvement!

    → Reply
»
3 months ago, # |
  Vote: I like it +3 Vote: I do not like it

Congrats to the winners!

Which country is hosting the next EGOI?

→ Reply
»
3 months ago, # |
  Vote: I like it 0 Vote: I do not like it

prvocislo orz

→ Reply
»
3 months ago, # |
  Vote: I like it -6 Vote: I do not like it

berr orz :D

→ Reply
»
3 months ago, # |
← Rev. 3   Vote: I like it +26 Vote: I do not like it

What's the solution to "Where is Waldo?" from the practice session (and where to submit)?

EDIT: found it, https://github.com/Kodsport/swedish-olympiad-2022/blob/main/lager/whereswaldo/submissions/accepted/sl_pq2.cpp

→ Reply
»
3 months ago, # |
  Vote: I like it +19 Vote: I do not like it

Any plans to release the test datas?

→ Reply
  • »
    »
    3 months ago, # ^ |
      Vote: I like it +20 Vote: I do not like it

    Test data can be found at https://github.com/zehnsechs/egoi-2024-testdata. Jury solutions will be uploaded there after the mirror contest ends.

    → Reply
    • »
      »
      »
      3 months ago, # ^ |
        Vote: I like it +10 Vote: I do not like it

      Is there any explanation as to why the 100-pt solution to lightbulbs has any sort of worst-case guarantee, given that it is randomized?

      → Reply
      • »
        »
        »
        »
        3 months ago, # ^ |
        ← Rev. 2   Vote: I like it +10 Vote: I do not like it

        We don't have a proof for it, but we do have some hand-wavy intuition about why the uniformly random case should be the worst, and the solution we have uses at most ~65 queries on that so we figured there was a large enough margin. We do have a deterministic O(n / log n) solution as well but its constant is much too bad; it seems unclear whether 85 queries is doable deterministically.

        → Reply
        • »
          »
          »
          »
          »
          3 months ago, # ^ |
            Vote: I like it +20 Vote: I do not like it

          What's the intuition?

          → Reply
        • »
          »
          »
          »
          »
          2 months ago, # ^ |
            Vote: I like it 0 Vote: I do not like it

          Can you please summarize the randomization solution for us? Since it doesn't have an editorial.

          → Reply
»
3 months ago, # |
  Vote: I like it +11 Vote: I do not like it

Good job by the organizers, the problems were great! I encourage everyone try d1D and d2D (and full score d2C if you have a free week, lol)

→ Reply
»
3 months ago, # |
← Rev. 2   Vote: I like it +3 Vote: I do not like it

Here is my solution to Day 1 Problem 4 "Garden Decoration". If you are going to participate in Online Mirror, don't see (I am writing now because the blog says we can discuss problems here):

Idea #1
Idea #2
Solution
Message

Anyway, if it is an intended solution, I will be really surprised.

→ Reply
  • »
    »
    3 months ago, # ^ |
      Vote: I like it +3 Vote: I do not like it

    I would be surprised too if this intended but there is a $$$O(n)$$$ solution by pure construction, one of our IOI team members found it during virtual. It's pretty nice imo.

    Solution

    Credits to isaachew

    → Reply
»
3 months ago, # |
  Vote: I like it +17 Vote: I do not like it

Congratulations berr! You deserved it well :D

→ Reply
»
3 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Is it possible to give virtual after July 29th on any of the platforms?

→ Reply
»
5 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

Does anyone know which country is hosting EGOI 2025?

We knew the dates & host by this time last year.

→ Reply