BOI 2023 Blog

Experiences of the Balkan Olympiad in Informatics 2023 in the city of Maribor between October 29 and November 3

Bibin Muttappillil

Saturday 28th of October | Andrej

After almost meeting on time (with 10110^{1} minutes of absolute error tolerance) (and without Mark) at HB, we had lunch at Rice Up. We went on to do a simulation contest of BOI 2018 day 2. Bibin also decided to solve the problems with us. We all solved the easiest task, with widely varying levels of struggle with implementing, which culminated in Bibin’s implementation, after 3 hours, of a 4-pointer data structure along with some kind of smaller to larger (there was no obvious reason to use any trees in that task, by the way). Most of us also solved the interactive task, whether during or after the contest.

After this more or less successful training, we ate dinner in an Asian restaurant, where we finally decided to play some Tichu. Sadly, one of Yaël’s cards went missing, even though he had counted all of them the day before. But since we are all passionate Tichu players, each of us brought (at least) one deck, so it wasn’t a big issue. We then went back to HB to take the train to our hostel, and we continued the Tichu game on top of my suitcase while standing in front of the train’s doors, which went completely unnoticed by the other passengers. Yaël and I somehow managed to get a Doppelsieg but fail a Tichu at the same time.

After a very complicated check-in and a long struggle to get the elevator to work, we managed to drop off our stuff in our rooms and got back down (the elevator was slightly easier to operate this time) to play some Tichu (you may start to see a recurring pattern here). After around 1 hour, we somehow convinced ourselves to prefer sleep over Tichu and got back upstairs. Yaël and I discussed what we were going to do on the train ride, and we decided that writing an hourly blogpost was going to be a great idea.

Sunday 29th of October | Yaël

What we did today.

Short version:

Plot for Tichu points over time for Mark/Hannah and Andrej/Yaël over 45 round with over 4000 points

Long version: We played some Tichu.

Actual long version: We played a lot of Tichu.

Unimportant sidenotes:

8:00: Andrej got scared of oversleeping because of the time change. But we were on time, which surprised Bibin. We sadly looked at the pancakes without being able to take any, as Bibin hadn’t booked any breakfast (too expensive). After an impressively unimpressive logout, we got to the train station. There, we had to wait for quite some time [1].

9:00-ish: We got breakfast and, most importantly, chocolate at Migros, and were afraid about not getting any lunch on the ride (if you want to know why, see BOI 2022). Mark somehow found us there, which is a great achievement at Zürich HB in my opinion. To get some exercise before the train ride, we went upstairs and back down again with an additional Alen.

10:00 Finally, we got to the important part. You may only read on if you find out what it is!

Hint:It was already mentioned in this post

As you may have guessed, we started playing some Tichu. Andrej had the absolutely genial idea of playing to 3000. For the first round, it went well for us, but after this, things rapidly deteriorated.

11:00: Same as 10:00, with a lot of inapropriateish use of the -ish ending, as in “Ach, this is okayish”. The final score already rose to 10’000.

12:00: We changed trains and went to the restaurant (the food from Migros still hasn’t been eaten yet). There, Hannah could choose between some very trustworthy pink stuff and some Indian masala stuff. She chose the pink stuff. As the table was better, we continued with what we were already doing at 11:00.

13:00: See 12:00.

14:00: See 13:00.

15:00: Do not see 14:00. We did some stuff on our computers, being good brave nerds, and I also think there was some funny quote by Hannah. Unfortunately, the following conversation just took place.

I remember saying something and you saying it would get into the blogpost.

— Hannah

Ok, then we just put this in.

— Yaël

16:00: Ach, doing this every hour is way too tiring.

18:00: We went back to the restaurant and did things very similarly to 12:00.

20:00ish: We got back and found out our places had been deemed unoccupied. As we were winning (some may say for once), I tried to stop playing by telling them I absolutely needed to write this blogpost. They still forced me, which led to the dramatic decrease seen in the graph and me asking for more rounds to get the points back (this didn’t work very well, as you may see…).

21:00: The 10h long train didn’t even come late, so we got the planned one.

23:00: Finally got to the hotel, where we started to analyse the Turing completeness of the lights in our hotel room. Andrej spent quite some time drawing the following diagram:

Logic curcuit diagram describing the behaviours of the switches and the lights of some participants hotel room

The result was that given a constant “On”, a constant “Off” room, and an infinite number of other rooms, the hotel is Turing complete.

P.S. This was not written on the train ride at all, our plan failed miserably. It is actually done on Tuesday evening, ~2h before the deadline Bibin gave us. Any use of the present tense is intended [2].

[1]I won’t forgive you the missed sleep, Bibin
[2]This is a good method to avoid people telling you you made mistakes.

Monday 30th of October | Mark

First day of BOI!!! Finally, something more interesting than trains and practice contests. The day started off with a delicious breakfast at our hotel, which was by far one of the best ones I’ve ever had at an Olympiad event, with everything from pancakes and pastries to scrambled eggs.

In the morning, we had our practice contest, which went relatively smoothly except for some keyboard issues with the Swiss-German layout for some of us. After which, we had lunch at the contest site with some free time in the afternoon, which was obviously used for Tichu.

As the evening started approaching, it was time for the opening ceremony. We weren’t particularly excited about it, as these tend to usually be quite boring, with a couple professors talking about how cool everyone here is and that we should be ready for the challenges of the future, blah blah. However, this opening ceremony was a lot better. It seemed very professional, with an excellent host and a well-prepared program, including a Rick-Roll and a good balance of jokes and topics. As always, we threw chocolate at everyone and maybe popped the main balloon where every team was meant to write a message on, “cough” “cough” ***** (;

At the end, we had a nice dinner, but it unfortunately didn’t have many vegetarian options for Hannah (3/10 review from her). But it was time to socialize, our favorite activity. Bibin had a bunch of merch that we needed to give away, so he told us to take selfies with other teams with them wearing our merch in return for some ice cream. After talking to some teams and taking some photos, our social battery was running out. To solve this, we took a robot from a stand meant to advertise a university and used it to deliver some Swiss chocolate alongside some SOI merch.

Robot with a sign 'TAKE some Chocolate It's healthy' giving chocolate to foreign participant

Oh, and how can I forget about our small Tichu game. Tichu Score Update:

5430 (Mark & Hannah) - 4270 (Andrej & Yäel)

Tuesday 31st of October | Hannah

On Tuesday, we had to wake up way too early. I actually managed to be at breakfast on time, but sadly, there were no pancakes left for me. When the rest of the Swiss delegation arrived (late), I informed them about this tragedy. But as they came to the table, I realized that I had been scammed. They refilled the pancakes. So, what I learned from this is that you should not be on time if you don’t want to wait for the pancakes.

Anyway, after I also got some pancakes, we walked to the contest hall, where we spent the next 5 hours writing the contest. Mark and I spent most of this time trying to fix a MLE, while Andrej and Yaël actually got some ice cream equivalents [3]. Sadly, because we tried to get an ice cream equivalent for full score, neither Mark nor I actually got any ice cream equivalent.

We then successfully borrowed the Slovenian mascot (although they are not aware of us borrowing it) and realized we forgot something crucial at our hotel: Tichu cards! So we ran to the bus stop (obviously because we wanted to get to the Tichu cards faster and not because it was raining) and went back to the hotel. There, we played some games with our guide.

The next program point was Unlock Maribor, where we had to save Maribor from evil witches that wanted to send a big storm to Maribor. We were grouped with a Slovenian contestant, and I explained to him that it was really important for us to be the fastest group. He agreed, as, of course, saving Maribor from being destroyed is a really serious matter. Maybe we took it a bit too seriously because we finished about 20 minutes before everyone else, and as far as I’m aware, none of the other teams ran in order to be first. But we saved Maribor and managed to gather all the secret ingredients for the potion, so it was worth it.

We then headed to dinner, of course, not without playing Tichu on the bus and at dinner. Our plan of socializing at dinner (by sitting at a table where four more people could join us and hoping for someone to sit there) did not really work out, but that just meant more Tichu.

Now, there was a special program planned in the evening for Halloween, but as responsible SOI participants, we decided to skip it and spend our time writing blog posts (and playing Tichu). Thanks to Mark and me being very skilled Tichu players (we didn’t get lucky, we just have a talent for getting bombs), the day ended with the Tichu score of 7615 (Mark & Hannah) - 5085 (Andrej & Yaël).

[3]This is how Bibin tried to motivate us to use a good contest strategy.

Wednesday 01st of November | Andrej & Yaël

This morning, we were able to sleep in to recover for the contest and prepare for the one tomorrow, as it was the free day in between. Naa, actually not happening [4] . Our room came late in a planned way to maximize sleep and still be on time for the buses. In the bus, we spent some very long 5 seconds thinking about what to do, and finally decided on Tichu. It worked great and none of the cards fell down. Somehow, people didn’t want to play Tichu after some time, which had nothing to do with the game and everything to do with playing backwards in an uncomfortable position. So we tried to get some of the sleep we hadn’t got during the night (nobody mentioned Tichu at 11pm).

Thanks to the tickets from the Škocjan caves, we found out that everybody from our team, including the leaders, was between 0 and 17.99 years old. In the cave, which was decently big (only 100 meters high at it’s the highest point), someone did take photos of us, which is highly illegal according to the 5 times we got told (To all the employees of the cave: It wasn’t Mark from our team, address ———– ** , phone number +** ** *** ** ** ). We waited 30 minutes to get onto the Polybahn (everything which looks similar in some very imaginative way to the one at ETH should be called this way), and wondered whether we wouldn’t have been faster by foot. While the others were still coming up, Mark bombed yet another Tichu.

Exit of a cave in Slovenia Selfie with inside a cave in Slovenia

We went to a “random” (Andrej’s word) 4-star hotel and ate lunch there. The vegetarian options were rated by Hannah as e+πe + \pi out of 1010. Afterwards, we got rushed back into the bus and suddenly realized we were the only ones who could save Ljubljana from an earthquake caused by a dragon. For this, we entered a dusty apartment owned by a mad inventor and got told how to operate a piano by a booming voice. We ended up successfully activating the anti-earthquake machine in only 51 minutes and 51 seconds.

We still had time to explore Ljubljana and wandered off with our guides. At some point, 5 minutes before we had to be back at the bus, we convinced the guides to go back, even if it was only a “3 minute walk”. We got told off at as we were late by 5 minutes. Another interesting side story about the Greek team should be recounted here: Some guy had lost his phone. He got to the bus on time, but then wandered off again to find it. Our guide, Miloš, tried to find them, so we were even later. Finally, they were found (the Greeks, not the phone), and also yelled at because the organizers “didn’t care about the phone!”. Nobody wanted to play Tichu (again for the same reason as on the way to the caves), and thus Yaël and Hannah trained, adding up Tichu cards to 21.

The organizers were very creative, and we went to Piano, the restaurant which provided almost every single meal. Yaël probably forgot his jacket there.

[4]This is not laziness from the part of the authors.

Thursday 02nd of November | Mark

After waking up at the last minute, as the Swiss team always does. We went down to get some breakfast. As always Yaël ate a bunch of pancakes (somewhere around 10910^{9}) while me, Andrej and Hannah had a slightly more diverse breakfast. But who cares about breakfast, when we have a contest to do and hopefully get some ice cream scoops from Bibin.

Once we arrived at the contest site, we did a “Duck Rotation”, where we did a cyclic rotation of our four ducks, since some of us weren’t happy with the good luck effect that we got from the ducks during the first contest day. We then did the very motivational “Nandor Motivational Speech”, but this time we also got our Guide to do it with us. He was expecting a speech, so he was definitely surprised by our “Motivation”. During the contest, one of the problems turned out to have wrong test-data which they fixed around halfway through, and therefore they extended the contest by 30 minutes to compensate everyone for it. It ended up being the hardest problem, so most of us didn’t get affected by it too much.

After the contest, we were eager to look at the scoreboard to see our exact ranking as soon as possible. For me, Andrej and Hannah it wasn’t that interesting as we knew we weren’t going to get any medals, but for Yaël it was not yet clear. He got 250 pts on the second day, so there was a bit of hope for Gold. Unfortunately he wasn’t in the gold range, but a very respectable silver nevertheless. We later found out that HM would also be given out and quite generously, around 20%, but sadly Andrej missed it by a tiny margin.

To get our spirits high again, we continued our game of Tichu which we would have to finish today, as I would have to go back to Switzerland the next day already. The situation for Andrej and Yaël was looking quite desperate, so they ended up calling a bunch of Grand Tichus, sometimes successfully. But eventually Hannah and I were able to win the GRAND Tichu game to 10410^{4} points, with a final score of 10145 to 7255 and a total of 107 rounds played. While Andrej and Yaël did better than us at BOI, Hannah and I won the Tichu game, so you can judge for yourself who was more successful during this week.

Plot of the Tichu Game Scores

Guess where the bombs are hiding

After we finished our Tichu game we still had some time until the closing ceremony, which we spent by going to a local bakery and using our excellent Slovenian to order some pastries. At the closing ceremony, Yaël got his well-earned silver medal. In the evening we went to a fancy theater-like place for dinner, where we met with the Albanian team in hopes of being invited to next year’s BOI, which will take place in Albania.

Friday 03rd of November

Did some private sightseeing in Ljubljana.

Writing BOI with phone lights in the dark Selfie with Potato Statue

Saturday 04th of November | Andrej & Yaël

What we did today.

Short version: Sadly, we didn’t play any Tichu 😭.

Long version: See short version. [5]

Unimportant sidenotes: In the night, we didn’t snoar, we snoROARed (joke credits Dragons Dream Hostel). We had planned to buy postcards at the hostel, but realized that it is difficult to buy something if there’s nobody to sell it. So we walked to the train station, with Yaël again, borrowing the stylish neon yellow jacket from Bibin (At some point, he wanted to borrow it permanently, but this didn’t work out). As Bibin still wanted to have at least 24 postcards, we went to a bookstore, but not before getting our breakfast.

In the first train, we had to play Tetris with luggage and people. This led to Bibin sitting [6] at the other end of the wagon, but it didn’t matter as everyone just wanted to sleep (absolutely not understandable). For the next train, we had devised a masterplan (walking to the end of the train because the rest of the train was full), but Bibin and Andrej didn’t know about it, so they wondered where Yaël and Hannah had disappeared.

After the happy reunion, we didn’t begin to write postcards. As we were so hyped after our performance at BOI, we managed to solve the problem of matching leaders to participants in no time. Bibin was very happy we hadn’t bought even more postcards. We didn’t write the same thing to everyone. [7]. We didn’t didn’t didn’t didn’t didn’t write sarcastic postcards and blogposts.

We again had the amazing menu from ÖBB, and Hannah decided to take the untrustworthy pink stuff once more (she told us it was good, but nobody really believes it). At least we had dinner in a Swiss train, so she could take a crêpe (from the kids’ menu).

At Munich, we tried to spend our ice-cream equivalents. Sadly, Google Map decided it didn’t want to work, so we ended up getting cold and walking around the station. When we arrived at St. Gallen, it was already time to say goodbye to Hannah… and finally time to rest (at least for everyone except for the insignificant part of the delegation who still had to travel all the way to Geneva).

[5]This is not laziness from the part of the authors.
[6]Editor (Bibin) note: Bibin was in fact not sitting, but standing next to the exit in the first train due to the train being too full. Luckily, the doors leading outside were usually closed when the train was moving, so there was only a little chance of falling out of the train.
[7]censored by SOI leaders

Sunday 5th of November | Andrej

1am: I finally get home.

2am-[unclear]: Sleep.

PS: [unclear] >= 12 noon