A baursak week

The ICPC World Finals 2024 in Astana was the main event of this week (problems, results, top 12 on the left, broadcast recording, our stream recording). On our stream things did not go very well, as we struggled a lot getting problems accepted (only one + out of 9), so after getting 4 problems in the last 70 minutes including one in the last minute, we arrived at 9 problems with the penalty of 2238, which would give us a clear first place in the contest based on penalty time only :) With the usual scoring, it would only be enough for a silver medal.

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!

ICPC Astana mirror stream

Today was the dress rehearsal day at #ICPCAstana, which means even more time for socializing and side events, the most spontaneously designed of which was Mike Mirzayanov's pushup challenge (recording). I was expecting that there'd be a contestant that would easily beat Mike, but it was not even close as Mike still had a lot of strength left when everybody else dropped out (the last 3 pictured on the left). Well done to all participants!

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)!

ICPC Astana settling in

Most participants arrived in Astana over the weekend, but for me yesterday was the travel day. It started still in the dark (photo on the left), and when I arrived in Astana it was dark again. I also did not meet any other World Finals participants on the way, so it was pretty lonely. Having arrived in Astana though, I was instantly impressed by how smoothly everything goes, both with respect to ICPC and Astana in general, and of course I immediately got to meet some old friends, even at 22:00 on the hotel dinner. 

While I was in the air, the team registration, the talk by ecnerwala and the opening ceremony took place, which were also recorded (1, 2, 3). As part of the registration, team photos were taken, for the history but also for use in the World Finals broadcast on Thursday. On the right you can see the ETH Zürich team which graciously agreed to take me with them to Astana. Go ETH!

Today is a pretty chill day, with a few events such as the Tech Trek with another round of team Kotlin coding (recording) and the ICPC challenge (recording), but where most people just hang around in the big hall (a photo from the official gallery on the left) which reminds me a lot about the TopCoder Open onsite arenas back in the days, only it's at least 10x bigger this time: it is right next door to the contest floor, there is food, sponsor booths, but also a lot of space to just talk or play games with your friends. I think it is a perfect setup for an onsite contest!

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!

A family gold week

IOI 2024 was the main event of last week (problems, results, top 5 on the left). This time Kangyang Zhou beat everyone including the problemsetters — huge congratulations! I also lost 3 hall of fame positions this year: congratulations to Daniel Weber, Rain Jiang and Kshitij Sodani on the amazing performance over many years :)

The IC, ISC and HSC (and later the GA, I guess) had to deal with a controversy, and were put into a situation where no matter what they decide, somebody would feel very disappointed. However, I expect that the democratic process by which those decisions were taken (first within the IC, and then when confirming at the GA) helps those unhappy with the decision still accept it. And of course, I'd like to express my great respect to the IC members for navigating this very tricky case. Well done!

Similar to the last year, one author created several problems, which still impresses me a lot even though it is happening for the second year in a row. Well done Pikatan Arya Bramajati!

The 3rd Universal Cup Stage 9: Xi'an on Saturday was likely the last practice for many teams before the upcoming ICPC World Finals 2024 in Astana (problems, results, top 5 on the left). Team HoMaMaOvO have finally got back to the winning ways, wrapping up the contest with more than an hour to spare and with a respectable margin to the second place. Congratulations!

It seems quite hard for me to match this scoreboard with the (incomplete) list of teams coming to Astana, so maybe the readers of this blog can help: what is the highest-placed team in that scoreboard that is going to the World Finals?

There will be no contests this week, but this is just a small break before another huge event, as ICPC World Finals in Astana is already happening next week (website, brochure, some news on the left). So expect this blog to become a travel blog again, and we'll likely be organizing another stream of us solving the round in parallel, even though the meaning of "us" is unclear given that tourist is now a judge.

Thanks for reading, and check back next week for the Astana content!

A 4009 week

Codeforces Round 969 took place on Friday (problems, results, top 5 on the left, analysis, ratings). Edging out jiangly by just 5 points, tourist has finally broken the 4000 rating barrier. Even though one might say that 4000 is just a round number with no special meaning in the rating system, Gennady's recent run of form is simply amazing. He has won 6 out of his last 7 Codeforces contests, something that has not happened since 2015 (and even though I only checked Gennady's rating history, I can confidently say that it never happened for any other contestant), and which is even more impressive now given the much stronger competition in 2024. Congratulations!

The 3rd Universal Cup Stage 8: Cangqian followed on Saturday (problems, results, top 5 on the left). Gennady's team continued very impressive form here as well, winning the 6th stage in a row, and turning what was a very close two-horse race last season into a Max Verstappen-like domination (oh wait!). It was quite close this time, and by the end of the contest team HoMaMaOvO was solving problems faster, but they could not make up the time lost in the beginning. Congratulations to both teams and to the team Polish Mafia for the third full score!

Next week, IOI 2024 in Alexandria, Egypt will take front stage (participants). Together with the ICPC, the IOI is one of the two really big events in the competitive programming world. It is the event defining the year for the high school students who practice for it, and also the event where friendships can be made for the years to come. Good luck to all participants, check back my blog for the results next week (or just find them at the official website), and also check out the Swiss team's blog!