SOI Camp 2024 in Sarnen

27 participants from Switzerland met in Sarnen to train together for one week.

Jasmin Studer

27 participants from Switzerland met in Sarnen to train together for one week (10.02.2024 - 17.02.2024). They were accompanied by a delegation from Sweden and one from Slovakia. In many lectures, contests, and other activities they sharpen their skills in algorithms and practice to apply them in challenging problems.

Each day, some of the participants write about their experience. More photos can be found on Flickr.

Saturday, 10th of February

Written by: Mark, Linus, Jerry, Andrej, Jovian, Pranavendra

The camp commenced uneventfully through the embarking onto a train from the city of Geneva by the participants Jovian and Andrej, accompanied by the newly appointed leader Theo, where they were one person short of being able to play Tichu, compelling Jovian in his unending boredom to complete his schoolwork instead.

Having arrived at the camp, the participants conspired with others to scam the SOI leaders of their chocolate, winning entire bags’ worth of Lindt (definitely not sponsored), by building bridges of questionable stability and material.

We ate Rösti (the food, not the mascot of the Swiss Mathematical Olympiad (hereinafter SMO)). After dinner, we embarked on our long quest to beat each other at various card games (i.e. Tichu, Tichu, and Tichu). But before that, we played Werewolf, which was resoundingly inferior to the Werewolf we knew from the SMO, where at least three of us nominated ourselves to be killed in order to escape the sheer boredom of the game.

Late at night, in the dark depths of the sleeping chambers, one could find a conspiracy of mathletes (citation: ChatGPT), who had previously stayed up past any of the other participants to play even more Tichu in peace. (That is, except Linus, who had defected from the club to go to sleep [1] for an actually healthy length of time.) We finally went to bed, dreadful excited for the upcoming contest.


Sunday, 11th of February

Written by: Vivienne, Hannah, Hongjia, Clara, Myriam

On Sunday we were very happy about the fact that breakfast only started at 8:00 and the contest at 9:00, which meant we could sleep for roughly an hour longer than at previous camps. The contest had tasks on various topics, so for three hours we distributed candy, ate yogurt before it expired and helped Stofl plan the optimal route for the carnival. After, we had lunch and played lots of Tichu, as well as listened to the solution presentations to all the tasks. Then we split up into three tracks and had lectures on MST, binary lifting, bridges and many more graph topics. After the lectures we were all pretty tired, so we woke ourselves up by playing table tennis on the very slippery floor, which made it hard to avoid falling on your face or crashing into the wall/other people. Luckily, nobody got hurt and it was very fun. Soon after we had dinner, of course played more Tichu and upsolved some of the contest tasks. We decided to end the day by singing pop songs to the wonderful guitar accompaniment by the Slovakian participants, which perfectly set the mood for the rest of the evening.

Monday, 12th of February

Written by: Elias, Benjamin, Till, Alex

In the morning we woke up at 7:45. After that we got ready and at 8:05 we went to get some breakfast. Like always, breakfast is cereal. After almost drowning in the cereal we took our professional gaming setups and we started the graphing contest.

3 hours of contest later.

We were exhausted. Instead of using our few remaining brain cells on more tasks we decided to play frisbee. We won :)

For lunch we got some Rösti with cheese and tomato delivered from the restaurant. After lunch there was a short break before the solution presentation of the contest tasks from this morning. Afterwards it was back to the grind with 4 hours of lectures and tasks about Dynamic Programming, today’s subject. For that we were again split up into beginner, advanced and expert tracks. Then we were finally able to relax and eat dinner. We got pasta bolognese (or with tomato sauce, for the vegetarians). After dinner we played games like tichu and sabotage for the rest of the evening.

Tuesday, 13th of February

Written by: Hana, Alica, Matúš, Matej

After breakfast, we had a contest. A DP contest. At the contest, we got a chance to try a few techniques we learnt the day before. It was a very challenging, but good contest. After the contest, lunch and solution presentations of the problems from the morning contest, we were divided into groups for a bit different contest. A contest of creativity. A contest of team work. A contest of having fun. In other words, the photohunt contest. After the contest in the morning, it was amazing to take a little break from torturing our brains and get some fresh air. We saw a Fasnacht march and we are convinced they had a contest for the best costumes and vehicles. We even had a little contest in catching candy thrown by the people in costumes. When we came back and ate dinner, we were looking forward to the contest results for the best group and the best photo. Playing Mao felt like a contest to us as well, it was very competitive, unlike guitar playing and singing which we did afterwards. We were also very exited for the team contest the next day. This long day ended with us going to sleep and dreaming of all the contests we will encounter in our life.

Group on photohunt

Wednesday, 14th of February

Written by: Kimi, Yaël, Lionel, Leo, Ursus, Aliaksei

Wednesday was a bit different from the other usual trainings-days. Instead of having a normal contest about some specific topic, we had a team-contest in groups of three for 3 hours. This time we had much more tasks, but also more people, still, we got only one computer! Because of that, we had to think more carefully as well using the time, that was spent on the computer, wisely. Ursus also somehow set Vivienne’s laptop drive to read-only during the contest. He’s still not sure if he did it with some shortcut, maybe her laptop is just weird. Luckily, they got that fixed shortly afterwards. At least no one had problems with it being on Codeforces instead of the SOI grader (Sarcasm (whitespace matter)).

Anyway, every group won balloons by solving a task. The balloons were a fun addition to the camp and delivered quick entertainment for the whole rest of the week.

For lunch, we had Röschti, not Rösti the Wolf, it was potato Röschti. (The -sch- makes the difference!)

Usually we had some lectures in the afternoon. Today’s topic was “Data structures”. The beginners track had a very nice introduction about Segment Trees. The advanced track also had Segment Trees as a topic, but they also made Math and SQRT-Decompositon, which was new to some of the participants. In the expert track they talked about Persistent Data Structures and they solved some interesting, but also hard problems.

But as always, what was our dinner? We had Schnitzel with fries. It was arguably the best food of the week.

After dinner, we played a lot of fun games. We played a long round of “Kommando pöpperle” but also Tichu and some other card games. Because we knew, that tomorrow we had to get up earlier than usual, we only played 2 games of Resistance. (only till 2 a.m)

Thursday, 15th of February

Written by: Sofie

Today everybody went on a funny excursion to the museum of transport. We didn’t. The Swedish delegation decided to explore this beautiful country. At 7:30 sharp (8:08), the 6 of us stood outside the doors and took “before” pictures. We were very excited to ascend 2500m vertically. The snow on the top of the mountain was the goal. The route was thoroughly planned and drawn out by Olle, our leader and Anastasia, a participant. We began walking around the blue lake.

After 1 hour, we finally arrived at the feet of the mountain. The ascend was to begin. The terrain was pretty good in the beginning, but it gradually got steeper and muddier. We followed the pomodoro technique and walked 25 min and rested 5 min. It was ultra-efficient. At 1300m we ate lunch. We could see the snow a couple hundred meters above us and we were very excited to touch it (Vlad wanted to eat it).

At 1600m we touched the snow! (Vlad ate it). It was an amazing feeling to look down at the valley, our adrenaline was pumping. We had planned to go further but decided to retreat at 15:00 to be down before sun-set at 17:51. Anastasia believed we could go to a higher top in 30 min (looked more like 4h). It got veto’d down by our leaders Olle and Joshua. The descent was in my opinion more tedious than the ascent. My knees died. I was utterly drained of energy, but Olle and Anastasia proposed to go to another mission: take a detour and walk AROUND the lake. I said no, Theodor said no, Vlad said no and Joshua said no. They left alone.

At 19:01, the rest of us arrived, happy and delighted but drained. Sitting down has never felt nicer.

Comment: Vlad said the snow tasted well.

Friday, 16th of February

Written by: Andrei, Enea, Carl, Ferdinand

After breakfast, we participated in the I-Cup. It was a five hour long contest, where we had to implement the techniques and theories we had learned this week. It was very challenging because we had to incorporate everything we learned.

After the contest, we had lunch and a solution presentation. Then we had some free time.

After dinner, we presented the photos from the picture hunt on Tuesday. Then we had the long awaited ranking of the I-Cup from the morning. It was a simulation of 20 minutes where we could follow along the submissions from the contest. The full score for one of the tasks was achieved after 4 minutes and 15 seconds. The highest points, 600 out of 800, were achieved by a participant from the Slovak delegation. After this we had one of the admired Ferdinars! Since it was the last night, nobody was going to sleep. There where two rounds of The Resistance that lasted over 3 hours! After that some people even went for a walk late at night!