The fourth round of the IIOT (International Informatics Olympiads in Teams) is starting in two days, on February 3rd 2022! The open contest will be 3 hours USACO-style, starting from 17:30 CET, and ending 27 hours after that. In the meanwhile, you can enjoy our teaser below and try to guess the next nine problems from the hints :)
This contest, of a lower difficulty level than the IOI, is intended for teams of 4 contestants from the same high school (check this post for further details). However, everyone is welcome to participate to the open contests!
If you want to participate, you must:
- Visit the contest website: https://mirror.squadre.olinfo.it/
- Click the link "register", fill out the form and then click on the register button and then "back to login"
- You can now log in with the same username and password you used to sign up
- If the login is successful you will be ready to participate, just wait for the contest to start! (and maybe save the page in your bookmarks, so that you can quickly get back to it when the contest begins)
- When the contest starts, you will see a red button. Click it when you want to start your 3 hour time window!
- The ranking for each contest will be available at https://mirror.squadre.olinfo.it/ranking/ after the start of each contest
- The tasks will also be available for training in https://training.olinfo.it/#/tasks/ few days after the contests
- Good luck and have fun!
We hope that you will join us or encourage your students to do so!
Tommaso Dossi (on behalf of the Italian IIOT organizers)
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What was the intended solution for Marathon 2 for full points?
I reduced the problem to maximum weight matching on a complete graph (shortest path subgraph of only the checkpoints + {0 and n-1}. I think this is no easier than just maximum weight general graph matching, so I found a code for it here: MiracleFaFa Blog.
But aren't general graph matchings extremely hard for an olympiad? I don't see how anyone would solve that in-contest.