## Friday, April 19, 2024

### A turning red week

The ICPC World Finals in Luxor was the main event of the week. The finals for two years were running in parallel, and our team was solving the mirror of the 2022 season, the 46th World Finals (problems, results, top 12 on the left, official broadcast, our stream). MIT team was dominating the round, solving 8 problems in less than two hours, getting to 9 within 3 hours, and leading by 2 problems for a long time. This reminds me of my own participation in 2005 World Finals (frozen detailed standings, final coarse standings), where we got to 7 problems slightly after the 3 hour mark and were leading 7-5, and with a huge advantage in penalty time, only to get stuck in problem G and have the Shanghai team overtake us thanks to solving 3 problems in the last hour. A very similar thing happened here with another team from China, Peking University, who solved 3 problems in the last 70 minutes and overtook the unlucky MIT team who was stuck with 25 incorrect attempts on problem S. Congratulations to both teams on the amazing performance!

Problem T "Carl's Vacation" was the trademark World Finals geometry problem. You are given two right square pyramids with integer base coordinates, integer height, and non-intersecting (but possibly touching) bases lying on the same plane. What is the shortest path between the tips of the pyramids that always goes either on the surface of one of the pyramids, or on the plane? The coordinates are up to 105, and the output must have relative error of at most 10-6. Can you see a way to implement this without getting stuck in the details?

The finals of the 2023 season, the 47th World Finals, had 5 shared problems and 6 unique problems (problems, results, top 5 on the left). The Higher School of Economics team took the lead a bit before the 2 hour mark and held it for most of the remaining contest, only allowing the MIPT team to lead briefly for 10 minutes in between. Unlike the first contest, nobody was able to solve the 10th problem and therefore HSE's win stood. Congratulations!

For me, the most amazing part of the Luxor event was meeting so many friends and acquaintances who live all over the world. The ICPC community is amazing by itself, and it also serves as a basis for multiple sub-communities that came together to meet in Luxor, such as the ICPC Live team, or the Universal Cup organizers and participants, or the ICPC alumni who now work for the sponsors, or just came as guests, such as myself. Huge thanks to the organizers, to the sponsors, and to the participants!

Thanks for reading, and check back next week.