AtCoder World Tour Finals 2026 in Japan was the main event of this week ( problems , results , top 13 on the left, commentary recording , analysis ). With the three last problems significantly harder than the first two, it all came down to choosing the hard problem that fits one's strengths the most, as there was only enough time for solving one hard problem, despite the round lasting a whopping 7…
Long time no hear! I wanted to mention three contests with onsite rounds happening soon. First off, Wincent DragonByte 2026 qualification round is ongoing and will continue for about 12 more hours (you won't need so long to qualify!). This is a new competition (this year is the second edition) with onsite finals in September in Bratislava, and with problemsetters of the IPSC fame. Everybody can…
Codeforces is running Blitz Cup 2026 , and my Round of 32 match against feecIe6418 starts in about 1 hour! You can watch my livestream or the scoreboard . Here is the full bracket .
ICPC EUC 2026 starts in about two hours ( 9:30 Warsaw time , photo on the left from the official gallery ). Here are some useful links: Official website Teams Scoreboard Problems Livestream Note that these problems will be used for the Universal Cup next weekend, so please don't look at them (and don't watch the livestream I guess?) if you are planning to participate there. In the other case, do…
The Dec 22 - Dec 29 week wrapped up the competitive 2025 on the major platforms. The 4th Universal Cup. Stage 10: Grand Prix of Wrocław took place on Saturday ( problems , results , top 5 on the left, onsite results , analysis ). Team USA1 were not the first to finish, but they were still the fastest overall, and extended their streak of 8 (!) won rounds in a row. Well done! Codeforces Good Bye…
Yesterday I have arrived in Warsaw, which will host ICPC EUC 2026 this Sunday. As you can see on the left, Warsaw in Feburary (much like Wijk aan Zee in January) is very conductive for indoor activities, which is perfect to be able to truly focus on a programming competition. I have arrived too late to get to the opening ceremony, but from the slides that were shared it seems that, among other…
Codeforces Global Round 31 last Friday wrapped up the 2025 Global Round series ( problems , results , top 5 on the left, analysis , serie standings that use the "sum all 3" instead of the actual "sum 2 best out of 3" scoring system). I spent way too much time on implementation and debugging once again, solved A-F1 and then decided not to go for even more standard-ish implementation in F2 and…
The Universal Cup Grand Prix of Jinan was the only round of last week ( problems , results , top 5 on the left). This season is turning out to be the most one-sided to date, with team USA1, which won all previous seasons , winning 8 out of the first 9 Grand Prix. This particular contest was very one-sided as well, with USA1 winning 13 problems to 10, with more than an hour to spare. Well done! One…
The last weekend was packed with contests. First off, the Yandex Cup 2025 onsite final took place in Istanbul early on Saturday ( results , top 5 on the left). The usual suspects topped the scoreboard, and Kevin got the highest score in each problem and earned the well-deserved first place. Congratulations! This was already the 10th cphof-worthy contest of 2025, and with the addition of the…
Meta Hacker Cup 2025 Round 3 on Saturday narrowed the field down to the 25 finalists ( problems , results , top 5 on the left, my screencast ). After solving B relatively quickly, I got stuck on A for about 50 minutes. The overall solution plan was relatively clear — k =2 is a special case, in all other cases we can achieve the minimum amount derived from the area by solving greedily with some…
Before I cover the last week, I need to mention the 4th Universal Cup Stage 5: Nanjing, which happened the week before and which I forgot to cover ( problems , results , top 5 on the left, analysis in Chinese ). Even having only 2 out of 3 teammates did not stop team USA1 from winning by a whole problem. Congratulations! The Universal Cup can't stick to the plan of having rounds only every other…
Meta Hacker Cup 2025 Round 2 was the first event of the Nov 10 — Nov 16 week ( problems , results , top 5 on the left, analysis , my screencast ). Once again getting the problems right was more important than solving them fast, but it is still more impressive to do both at the same time. Congratulations to Benq and Um_nik who got quite a margin in penalty time compared to the rest of the full…
Codeforces Global Round 30 was the main event of last week ( problems , results , top 5 on the left, analysis , my screencast ). I was doing quite well on the first six problems, but got bogged down with implementing treaps with some additional accounting for problem F2, spending more than an hour on that. Right after the contest ended, I had two thoughts: Wow, the people at the top of the…
Pinely Round 5 started the competitive part of the last week on Thursday ( problems , results , top 5 on the left, analysis ). This was my first individual appearance in a screenshot on this blog since April 2024 , so I think it went pretty well :) I was figuring out the solutions pretty quickly, and did not get stuck in implementation like I often do. However, it was not nearly good enough for…
The Universal Cup Stage 3: Polar was the first event of this week ( problems , results , top 5 on the left, still not updated cup standings ). In all three stages of this season the first two places went to the same two teams, and in odd-numbered rounds team USA1 comes out on top, if only by less than one wrong submission this time. Congratulations to both season leaders! AtCoder Grand Contest 074…
Meta Hacker Cup 2025 Round 1 was the main event of last week ( problems , results , top 5 on the left, analysis ). As usual in the early Hacker Cup rounds, one has to balance the speed against the amount of effort you spend to test your own solutions before attempting to submit them. There is just one attempt per problem, and the submission result is only revealed after the round ends (a pretty…
The Universal Cup held its Stage 2: Paris during the Oct 6 - Oct 12 week ( problems , results , top 5 on the left). This was one of the very rare occassions where the winner seemingly was not a veteran team, but a team THU1 consisting of university students. They were already ahead of the usual suspects on 12 problems by penalty time, and solving the last problem 10 minutes before the end was the…
Squarepoint Challenge, also known as Codeforces Round 1055, was the first event of last week ( problems , results , top 5 on the left, analysis ). This round followed a different problemsetting philosophy , so for me it was mostly about figuring out the best way to implement a solution and actually implementing it, as I got the general idea for solving each problem, including H2, fairly quickly.…
After a bit of a summer lull the contests are starting to gain steam again. Last week started with the Codeforces Round 1053 on Wednesday ( problems , results , top 5 on the left, analysis ). I got stuck in the implementation details of problem D for almost a full hour, then spent some time implementing a local tester for E2 to see how far my solution for E1 was from solving E2 (quite far) and…
Codeforces Global Round 29 was the main event of last week ( problems , results , top 5 on the left, analysis ). Only 3 participants managed to solve the 5500-point problem H, and they occupied the first three spots. Well done to ecnerwala, jiangly and ksun48! The big story of the round though was the solve count for problem G. According to the screenshot in this post the solve count was at 184+…
Codeforces Round 1048 on Monday was the first competition of this week ( problems , results , top 5 on the left, analysis ). The round was unrated , which has delayed my inevitable downfall: I solved A+B(in the same wrong way as the problemsetters)+C1+C2 in 32 minutes, but could not solve anything else in the remaining 2.5 hours, even though I tried my hand at all remaining problems. In D , I came…
ICPC World Finals 2025 #ICPCBaku was the main event of the week, and for many the main event of the year ( problems , results , top 12 on the left, official stream , our stream ). The St Petersburg State University team was always among the leaders, but they collected too many incorrect attempts and therefore the almost flawless University of Tokyo team was leading with a better penalty time on 10…
Yesterday was the day of the Dress Rehearsal and the Tech Trek at #ICPCBaku. I am planning to solve the mirror contest on Thursday together with Kevin and Mateusz , so we used the Dress Rehearsal time to practice our solving and streaming setup as well (photo on the left). Unfortunately we could not practice the submissions since it seems that the mirror was not available for the Dress Rehearsal,…
The Alumni Talk and the Opening Ceremony were the main events of the ICPC World Finals 2025 today. Among other things, they demonstrated two of the best careers (according to my own perception, of course :)) that the ICPC crowd can choose: the Alumni Talk was about fundamental computer science research, in this case of the core graph shortest path algorithms, while the Opening Ceremony introduced…
Last week, the main round was the 3rd Universal Cup Semifinals ( problems , results , top 5 on the left, analysis , contest stream , closing ceremony stream ). For those not familiar with the Universal Cup, this announcement has some links for more information, but in short, it is a competition with many online stages throughout the year (40 in the 3rd season, but the organizers plan to reduce the…