Algorithms Weekly by Petr Mitrichev
Sunday, July 20, 2025
A 21st century week
Wednesday, July 16, 2025
AWTF25 heuristic day
Tuesday, July 15, 2025
AWTF25 arrival day
Sunday, March 2, 2025
EUC 2025
The EUC is a new contest that was launched last year, so this is the second edition. It brings together the top teams from 4 European regionals, providing them both an additional qualification path to the ICPC World Finals (detailed rules), and a significant onsite competition of its own, giving many teams who will not make it to the World Finals an opportunity to meet other students and enjoy the atmosphere of a big international competition, while keeping the travel costs in check. I am very happy to support this competition by volunteering as a judge for the second time!
We are also running a mirror contest on Codeforces, so come try it in a few hours! I think the problems are quite nice.
Friday, September 20, 2024
A baursak week
Among the people born in the 21st century, the Peking University team was very fast on the easier problems, had very few incorrect attempts, in the end earning the championship title with a huge margin of almost 300 penalty minutes. Big congratulations to them and to all medalists! And of course huge thanks to all #ICPCAstana organizers, you did a great job!
From the 12 medalists, 1 came from the Northern Eurasia division, 2 from the North America division, 4 from the Asia East division and 5 from the Asia Pacific division. Is it the best result ever for the Asia Pacific division?.. Sadly, the ETH Zürich team and other teams from our Europe division stopped at 7 problems solved and therefore just shy of the medal boundary.
Problem D in this round required a nice and somewhat unexpected observation. You are given n segments (n<=200000) on the number line. You need to pick one number from each segment, and then pair up some of those numbers in such a way that two numbers in a pair always add up to the given sum s. What is the maximum number of pairs you can form?One more thing that I did not mention yet about the ICPC World Finals Astana is the CLI symposium. It is a collection of talks by the people that run various aspects of the competitive programming community, for example this year's speakers were Nikolay Kalinin, Riku Kawasaki, Suhyun Park, Antti Laaksonen, Gennady Korotkevich, Andrey Stankevich, Yonghui Wu, Miguel Revilla Rodriguez, Joshua Andersson, Matt Ellis and Christian Yongwhan Lim. You can watch their talks on the ICPC Live channel as well: 1, 2, 3. They are not necessarily at the level of a TED talk, but I think they can provide interesting insights into the thinking of the speakers and into the functioning of the community.
Thanks for reading, and check back next week!
Wednesday, September 18, 2024
ICPC Astana mirror stream
It is finally getting serious tomorrow, with the ICPC World Finals 2024 starting around 11:00 Astana time (official live stream, scoreboard and problems, mirror contest, list of teams 1, list of teams 2). As usual, there are many very strong teams that have been practicing specifically for this event, so it is quite hard to predict tomorrow's standings. We can just relax and enjoy watching the contest. But of course go #ETH!
As the custom goes (2017, 2018, 2019, 2020, 2022), I have teamed up with Kevin and Nikolay to participate in the mirror and stream the proceedings. Here is a link to our stream, and in case something goes wrong, you can look for new instances of the stream on my Youtube channel and/or my Twitch. Tune in tomorrow around 11:00 Astana time (in the past, the round has started both a bit later and a bit earlier)!Tuesday, September 17, 2024
ICPC Astana settling in
One other thing already going on for three days is the ICPC Quest, which this post is also part of. There are various challenges aimed at people getting to know one another, and creating more content about the World Finals, and completing those challenges gets one some plush camels. I did not take part in it in the past, but I've decided to give it a go this year, and it's fun! I'm including #ICPCAstana in this post to fulfill one of the quest tasks :)
Thanks for reading, and check back tomorrow!