This is a part 2 of my other blog on the Psychotic_D situation. I highly recommend you see it before this one for context.

If you don't care that much, here is a quick recap of what was covered in the other blog before we get started: Psychotic_D had a ridiculously good performance on his friend's (wuhudsm) round. This let many people become suspicious of whether he achieved this legitimately. Then multiple accusations were thrown around and I did my blog doing my own investigation and compiling the most compelling evidence I found. The takeaway was that Psychotic_D was probably cheating along EndlessDreams, who would give him code for Psychotic_D to copy. Psychotic_D would alter them heavily to avoid plagiarism, but it was clear beyond a reasonable doubt that he was cheating.

Well, I finished writing that blog, responded to some comments and was ready to sleep when something clicked in my brain...

Part 1: Wait, who the fuck is EndlessDreams?

I mean, he is the first thing that appears when you open the TheForces group, he must be pretty important, right?

In addition, his solution to E on Codeforces Round 960 (Div. 2) (over the hololgram-sakura alt) was considerably different from the editorial solution. It was also not the kind of problem a random master could do in 30 minutes. Matter of fact, doing ABCD could already give you a red performance on that contest. Also, there is a team on codeforces with the founders of TheForces:

And EndlessDreams isn't part of it! I would assume that someone who made editorials for all the contests from them is a founder!

Well, maybe they are a founder, because on herav_singhhh's blog, there is another founder that is in the submission pairs.

amenotiomoi checks all the boxes! Think about it, if EndlessDreams is an alt and not the real leaker, the main should be higher rated. On top of that, he is supposedly chinese, like both EndlessDreams and hololgram-sakura. All that was needed was some proof that they are connected. The codes presented in the blog aren't that convincing, so I went for the place I forgot to investigate last time.

Part 2: Who the fuck is amenotiomoi?

In the investigation for the previous blog, I went to the TheForces website. However, I only entered the cf group for they had on it. This time, I entered their discord server. Normally, discord servers have features so that you can link your cf account to your discord account. So I just needed to search for "EndlessDreams" and then...

Jackpot! This guy is admitting to being EndlessDreams. Moreover, looking at his roles in the server, he was a moderator (indicating he had a high ammount of power) and had an international grandmaster role (which is the same rank as amenotiomoi):

However, it seemed like he never actually set his handle to amenotiomoi on the server. I could see him setting it to EndlessDreams but it looked like his account had no codeforces handle set to it at the moment. I was going to make an edit to the previous blog raising my suspicions when an interesting message came to my dms.

I changed my discord name to "ribbit" and joined.

Entering there, as said by our anonymous fellow, the discord account belonging to EndlessDreams was there. And he was confessing everything.

Part 3: Confession

At first I was scared to be banned and even recorded a video with all the evidence I found before noticing that it was not a server controlled by cheaters, but just a normal server where a bunch of cpers trained together. Some time after the previous blog went live, he posted this:

Well, I guess we found the guy. To everyone that doesn't know how this works, you cannot link your cf account to discord if you dont have access to it. He is certainly the one that had access to the account who leaked E to Psychotic_D

He also confirms that he is in fact EndlessDreams

He later went into more detail of over what happened

He also explained why Psychotic_D had access to his account

I ended up bantering with him a little, but for the story to fit i had to make one more question

...

I guess that's it!

Part 4: The confrontation

After this incident I may have shared the link to the server on another discord server. A bunch of people entered and we had a lengthy conversation with amenotiomoi/EndlessDreams/hololgram-sakura. Some things in it were pretty noteworthy though!

This is what he had to say when pressed on why he did it.

He was also pressed for details on other cheaters!

It was brought up that on a random cf round, another master previously accused of cheating 1_2_3_4_5_9 had a matching code with amenotiomoi: 210895554 210911093

This is what he had to say about it

This "code that chromate00 copied" is a case from 2023 where he supposedly copied a code from the internet for a problem. It ended up being that amenotiomoi was the source of that code. chromate00 has later apologized and reformed since that incident.

[REDACTED] also had a conversation in chinese with amenotiomoi.

Crazy if true.

Conclusion

Well, this has been a rollercoaster. It is kind of crazy to think that if one strong competitor wants to leak solutions to all problems they can just destroy the competitive integrity of competitive programming. I really hope that amenotiomoi and Psychotic_D reform to some extent, but their account should definitely be banned. Thanks to everyone who helped me with the investigation and everyone who read this blog until here! I'm probably going to sleep.

By the way, amenotiomoi did send an ominous message in the middle of all the other ones

I guess I won't be awake to see it, haha.

Hello codeforces! You guys must have seen the recent blog accusing international master Psychotic_D of cheating in the most recent div2 round: Codeforces Round 960 (Div. 2). This is due to the fact that the author, wuhudsm is Psychotic_D's friend and that Psychotic_D had a ridiculous performance, winning the amongst official participants.

They are both big members of TheForces, raising suspicions of whether there was some collusions between the two.

At first i thought it was nonsense since the evidence was lacking, but after a bit of my own investigation I've compiled the most interesting pieces of evidence of why i believe Psychotic_D (along with some accomplices from TheForces) is in fact a cheater.

Case #1: Introduction

I first learned about the subject on herav_singhhh's blog. The blog is overall low quality and goes on too long on things that dont matter when catching a cheater. As an example, I will show a submission pair that does not strike me as suspicious that was in the blog (seeing this will help us see what is important on determining if someone is cheating): 192289785 and 192291152

A few things you can observe in this:

• The general logic of both codes is basically the same
• The code on the right uses maps and the code on the left uses arrays
• They handle cleaning the input differently
• The codes are very short

While they are suspicious, it is very hard to accuse someone of cheating on problems that are really simple to code. It is easy for multiple people to have a similar logic on problems like this, and it is expected that people will have similar ways of doing things. Moreover, I couldn't link Synergism's account to Psychotic_D (even though the former is obviously an alt). The fact that the submissions are so close in time and are so similar is suspicious, but not enough to ban someone. For us to have a conclusive veredict we would need a code that is:

• Reasonably long
• Has multiple copypasted elements
• Does things in an different enough way that the only explanation that they are so similar is that the code was shared.

And herav_singhhh provides with a submission pair that meets the criteria.

Case #2: A new take on cheating

Take a look at this submission pair that was also in the blog: 222750300 222766998

At first glance these submissions seem reasonably different. That's because Psychotic_D is a reasonably smart cheater. Most cheaters will take the path that takes the least effort, and because of that they are very easily caught. Check this diagram

Psychotic_D has some knowledge of how code works and tries to achieve the same result in an inderect way. Note how the two pieces of code have the exact same logic, but he shift things around if they dont necessarily require each other to work. On the previous case, he also swapped an array for a map, knowing that it would just make the code a bit slower.

However, he doesn't necessarily know why the solutions he is copying work. One particular, there is this $$$50 \times 50$$$ table that is calculated every call of solve. If you check any other submission of this problem, you will see that only a $$$30 \times 30$$$ table is calculated (maybe $$$32 \times 32$$$). I picked around 10 random submissions and none of them had that specific number. This is because the elements are at most 30 bits long. The original person who solved the problem probably wanted some extra space in case anything went wrong, but it is certainly unusual. Psychotic_D was probably too scared of causing some type of issue by changing that constant, not knowing why it was there, and just copied it.

EDIT: It came to my attention that Psychotic_D actually tried to change the constant! Look at this submission: 222765150. He tries making the table $$$100 \times 100$$$ but it passes the limits for long long, resulting in a wrong answer. That was really funny to me.

There are also multiple places where random solutions differ from this general logic:

• Using a flag to compute if it.second is 0 instead of instantly returning
• Calculating the table outside of the solve function and reusing it for all cases
• Using an array instead of a map to calculate the frequencies

In addition, they aren't strangers, they know each other.

This is a screenshot coming from Psychotic_D, showing he had access to the account of EndlessDreams. EndlessDreams is also a prominent member on the TheForces group, where Psychotic_D is a manager. There are too many coincidences for this to be a misunderstanding.

However, one thing is lacking. The original claim was that Psychotic_D cheated on his friend's round, and so far it just shows that he most likely cheated in the past. We would need an equally suspicious code that confirms that he also cheated on that round. But where would he cheat from if he was the best between official participants?

Case #3: Catching the Mole

wuhudsm's round had an interesting problem: Catch the Mole. It was an interactive problem that where it really hard to create cases that break all heuristics. That way, a lot of codes that shouldn't pass, did. One of these codes is Psychotic_D's, where he just tried to query a vertex close to the centroid of the tree multiple times, removing the leaves in each iteration: 271612487. At first I thought he might've cheated on ABCD but did E legitimately, given that he did a scam solution after 1 hour of thinking. That would also explain why he got top 1, even though that clearly draws a lot of attention from him. Well, that was until i checked the submissions for E1.

Check this blue that did E almost as fast as tourist! What a prodigy! Let's see how he did in the round.

Huh, why would he submit E so fast and then leave the round? Well, it is clear after we compare his code to Psychotic_D's:

Here is the pair of submissions for you guys to check: 271612487, 271575642

This time it is so big that i needed to divide each code into two parts. Note how similar it is to the other cases:

• Copied submission uses "Delta" instead of "solve"
• Making changes in places that cant affect the code: putting stuff in functions, changing variable names, changing while(true) to while(1), etc. Anything that an intermediate coder would see that could be changed was changed.
• Weird manneirisms in the code stay the same. For example, both use the same check to find a vertex close to the centroid: checking the value of abs(sum[i] - sum[1] / 2).
• Refactoring of functions to achieve the same goal. Look how he breaks apart dfs2 into cln1 and cln2 to do exactly the same thing in a more roundabout way.

Also note that hololgram-sakura's description is also in chinese, like EndlessDreams. Also $$$^2$$$ note that Psychotic_D has a TLE submission on this problem for forgetting to put the code that clears the array somewhere, choosing to put it in a really weird spot in the end: 271611264.

It is pretty clear to me that hololgram-sakura is an alt of EndlessDreams and they have been cheating on many contests together, probably doing them in a team like other high rated cheaters did in the past. By those 3 accounts you can see how the methods of cheating from Psychotic_D evolved through the years, going from minor alterations on easy problems to major refactors in hard problems.

In addition, [REDACTED] helped me by finding more suspicious submission pairs: (269238719,269257401) and (269250817, 269264255). They follow most of the trademarks that happened on previous submissions.

Conclusion

It is always disheartening to see high level competitors cheating. As someone who loves competitive programming it is sad to see so many people that had potential to be great fall for such tactics. I plead other participants to be more honest in the future, what use is there in getting more rating if you know you didn't deserve it? Doing bad in some rounds is normal and you shouldn't try cheating to remedy it.

Anyways, take care!

Also MikeMirzayanov please ban him!

EDIT: A lot of stuff happened and now this blog now has a part 2, check here.

Hello codeforces!

I was reminiscing about the brazilian TST that just happened and figured it was way too crazy not to share with everyone how it went. So as a follow up to this blog I'll be going through my experiences at the event. Get ready for a ride, because this is gonna be a long one.

Day of Arrival: Coming out of the closet

The people of my school all gathered in a bus to go to the hotel we were staying at. That bus made a beeping noise every time we passed 90 km/h, and considering we were travelling at night, we were hearing that noise way too often! While in the ride, I stole LFFB_'s laptop and started playing Osu on it. Even though I was playing on the touchpad and the bus was bumping around, I was able to clutch out an S on "Pepsi Man", which was quite a challenge despite being on relax mode.

After that, I gladly returned his computer so he could do Advent of Code while still inside the bus.

Arriving at the hotel, they got us something to eat and after LFFB_ showed a bit of his piano skills, we quickly got to know our rooms. We started hanging out in one of them when _rey got the wonderful idea of getting inside the closet, almost breaking it and leading to this awesome moment:

"Get out of the closet Pedro, get out of the closet!" — Everyone

Warmup Day: Brazil vs Korea

Overall, pretty uneventful day. We got breakfast and headed to UNICAMP, the university where the TST would take place on. It was the warmup day, and one of the problems in it had a very glaring issue where it was literally impossible to solve because the setters forgot that 4^7 < 8!. We had to stop warmup early tho, because Brazil was playing in the world cup (and it is pretty stabilished that no one works or goes to school while Brazil is playing in the world cup).

Yeah, we went to a different room so they could project the game for us. It was really cool.

We go back to our rooms, talk for a bit, turn on the air conditioner, and sleep.

TST Day 1: Tragedy arises

I wake up with a stupid ass headache. My bed was right below the air conditioner, and it looked like that AC was there since the 90s, which was probably why have waken up so bad. Since the first day of the TST tends to be really easy, I thought everything was fine and just hoped the headache would be gone before the contest starts.

Contest starts and I still have the headache. It had 2 problems for 2h30 and was also much harder than expected. I end up having a wrong idea for one problem, then went to the other problem and got a correct idea, but my code was really really buggy. They gave everyone an additional 30 minutes because the checker for that problem was also bugged. I ended up debugging the problem in the last 17 minutes of contest, ending up with 121 / 200 points, which would be around 70 if they didnt give 30 minutes to everyone. I was really really angry at myself, but everybody tried to cheer me up. It really helped me, even though I would stay angry for the rest of the day. Funnily enough, what helped me the most was ar_paixaos19 saying "you're all bitchy today but everybody knows you're going to IOI in the end".

After having dinner, we were going to have the "Shopping Day", where everyone at the event would go to a shopping mall and walk around on it. When we got into it, the goal was simple: finding a pharmacy so I could buy headache medication (it only got worse after the contest).

The mall was really big and in the middle of our search we found an interactive art piece, where everyone could swipe their fingers and draw anything into the wall. We didn't take a picture of it, but it looked something like this:

Of course, we drew lots of dicks on it.

We found our way to the pharmacy, got the medication, and started going to random stores to mess around in. In one of them, we found this very promising piece:

The text says "Which Fini is perfect for you?", but the screen just had Microsoft Solitaire Collection running on it. It turns out it had Windows 10 on it, so we did what anyone else would do in that situation: we solved watermelon on it. For some reason we couldnt use the cf text editor, but we opened notepad and did this.

I have a video of it, but since i dont know how to embed it in cf blogs, lets just have _rey posing for a photo with the AC while I was recording it:

"It's a video, Pedro" — Mee

We go back to our rooms, and before sleeping, my friend joaof noted how suspicious my headache medication looked and took this photo to incriminate mee:

He later said to random people that I bought viagra at the mall while showing this photo.

TST Day 2: A new hope

I made sure not to turn on the AC in the night before, so I was headache-less. The scoreboard for day 1 came out during breakfast, and I was tied in 5th with a bunch of people. Honestly it was much better than expected, but still outside of IOI range. Not knowing what to expect, we head out to UNICAMP.

Before the contest, we had a class where they went through all the solutions for the previous day, on top of some extra stuff. My friend group all had caps that the organization gave us when we got to the hotel, and in the middle of the class we decided to merge all of them into one:

You guys can't see it, but there is an extra cap facing backwards that doesn't appear in the photo.

There was also pizza for lunch. They would bring us pizza through a door and people would get the slices from the plates they were carrying. Normally, everyone at the entrance would instantly get all the pizza, so the waiters would extend their hands really up in the air to not allow them to get it before everyone. It is said that the "Pizza Day" is also part of the Selection for IOI, because only the strong would be able to get themselves fed before the contest.

We then finally head to the contest and get our setups ready. I was really anxious before it all started. So, as a lucky charm, joaof hands me a fucking shampoo bottle.

The results speak for themselves though. This is the scoreboard in the first day (without the shampoo bottle):

This was day 2 (with the shampoo bottle):

Note that my name is "Leonardo Valente Nascimento".

Even though I was back into IOI range, it was not an ideal contest for mee. It had 3 problems, but it was a 3h30 contest, and I spent around 2h30 of them on a wrong idea for the problem "Verba". Luckily, "3Swap" looked a lot like this problem, which AnandOza helped me with a really long time ago, so I could code it for 91 points in half an hour. Thanks Anand!

Back at the hotel, I watch episode 9 of Chainsaw Man at my room. My roomate vladimir050 noted that I was screaming out of nowhere while watching it, and he thought I was talking with him. It was pretty good.

TST Day 3: Shopping Day 2

Cheered up once again, we head to another contest day. This time, it was a 5 hour contest, completely IOI-style, so I knew it was my time to shine.

I forgot to take a screenshot of the day 3 scoreboard, but I did 286/300 points, getting passed only by LoboLobo, which AKed the contest. I later came to know that the guy who created the problem I did 86 points on was morete, one of the teachers of an IOI training camp for mee, Deepesson and LoboLobo. He also stole my ID in one occasion. The character from the statement was supposed to be Leonardo, but one of the setters decided to change it to not pressure any of the contestants.

After the contest, we also had a second "Shopping Day", on an even bigger shopping mall.

We first headed to a houseware store where we obviously bought nothing, then for a book store that had lots of manga. On that particular store, there was a wall with a bunch of talented drawings, which i think would be cool for you guys to see:

As someone that is watching Chainsaw Man religiously, I was trying to find a Chainsaw Man volume. It was really hard finding one that didn't have a naked woman on the cover, but in the end I settled with this:

In response, perchuts had one thing to say: "She has a big heart".

We then had a new goal to achieve: ar_paixaos19 had neck pain and we needed to find a pharmacy to buy medication for him. The problem is that the mall was so big that it was particularly important that an instructor was keeping an eye on us. We proceeded to completely ignore that fact and started wandering out into the nothingness.

After doing a very exhaustive DFS through the mall, we finally found a drug store. ar_paixaos19 buys his medication while i try taking on and off random stuff from mee so that the weight machine in the store could say that I had exactly 69kg. Both of us were successful.

From left to right, we have mee, _rey, ar_paixaos19, LFFB_ and vladimir050. Note that Vladimir has an IOI cap. We exchanged caps because I lost the cap OBI (Brazilian Olympiad in Informatics) gave us and the IOI cap couldn't fit my head. He liked it a lot, as we can see in the picture.

We continue walking aimlessly until we meet a group that actually had an instructor! As that instructor scolds us, _rey notes a very scary thing: he couldn't find his phone anymore. As noted in my first blog, he has lost his phone in every single OI event he has been in, and this time he "felt like someone was getting it out of his pocket". Since time was running out, we just regroup with everyone so we could leave.

In the bus back to the hotel, we find out that someone found his phone at the mall, so apparently no one actually stole it (despite what he said earlier).

When we get back, the organization told us that not only we got back late because of the shopping day, but we would have to get up early because Brazil was playing at the world cup again tomorrow. We ended up getting a sub optimal ammount of sleep because all of my friends decided that it was a good idea to mess around in my room, on top of the already dire conditions.

TST Day 4: Dawn of the last day

It is a known fact that the last day of TST in Brazil is completely crazy. This year, it did not disappoint.

Everyone at the top 4 just had to get a small ammount of points to guarantee IOI, so we were all relaxed. In my case, for example, I had to get 135 points. Because of that, on top of the fact that little to no one actually got a good night of sleep, we had more people sleeping during the class than usual. Take this funny photo of _rey as an example.

He actually slept in all classes for at least a little bit, but this photo is particularly funny.

Then we go to the same room as before to watch the game of Brazil vs Croatia. We were only able to watch the first 2 halves though, as the extra time would clash with the time reserved for the contest. The setters assured us that they would keep us in touch with the game through the announcements, so there was no protests about it.

It was another IOI style contest, with 5 hours for 3 problems. As any dignified last day of TST, it was much harder than the other ones. I ended up getting the 135 points I needed around the middle of the contest, and then noticed I was way too sleepy and tired from the other days to stay focused and think on the problems. Therefore, I followed this algorithm from that point on:

• Code all subtasks I know
• Leave the contest room
• Find a random place to sleep
• Sleep
• Have an idea for a random problem
• Go back to the contest room
• Repeat

This was particularly effective, as it got mee 210/301 points by the end of the contest, the highest score on it. In fact, if we just consider the last 2 days, I'm exactly 1 point above LoboLobo :sunglasses:. Before anyone asks, the contest was in fact worth 301 points, as the last problem, "Anido Primes", was worth exactly 101 points. I asked about it in the clarifications, but the only answer I got was "101 is prime". All the subtasks on this problem were also worth a prime ammounts of points. The problem also had nothing to do with primes or Anido (the coordinator of the brazilian olympiad), which is kind of funny.

After the contest ends, we head to a ceremony where they hand the medals from the national olympiad to everyone that came to the event, and also announced who would be going to IOI, CIIC and EGOI. Our parents were also invited to come and the ceremony can be watched here. It had some pretty funny moments, like a pikachu showing up to receive a medal and Anido saying that EGOI 2023 will be in Switzerland instead of Sweden. It was also there that I got the news that Brazil lost the World Cup, as the setters just notified us when Neymar made a goal, but not when Croatia did one and eventually won the game, so that we wouldn't do the contest saddened. I also handed my cap to my little sister, which ended up liking it even more than I did. The IOI team also took that photo that appeared in my first blog during the event.

We then head back to the hotel to have our last dinner there. Contrary to what you might be thinking, this is where the real event starts. It turns out that the last day of TST in Brazil has only a single rule: nobody sleeps.

I send a message to our whatsapp group asking what the plans for the night are. While waiting for the answer, mee, ar_paixaos19, _rey, vladimir050, LFFB_ and Deepesson go to a room to play a brazilian card game called Truco. My team won the last game and I was popping off when we received a message from LoboLobo: "Get down to the pool".

We go to the pool, where we probably weren't allowed to be that late at night. Not everyone went in though, only mee, ar_paixaos19, _rey, vladimir050 and LoboLobo. The ones who did, however, did so in stylish manner, specially doing front flips. We would keep getting outside of the pool, running back in and front flipping into the pool again, which was very dangerous considering how slippery the floor was. We then found 3 metal bars, which were supposed to be used to put parasols on, and started playing with them like they were swords.

"IOI is too small for the both of us" — LoboLobo and _rey, probably

The third metal bar is with mee, even though I don't appear at the picture.

We also used the bars in an inventive manner. We would fill the inside of it with water and use them to wet the people that didn't want to get into the pool, specially Deepesson. _rey was the only one who ended up using that strategy effectively though. In the end a person from the hotel staff came and respectfully took the metal bars from us, figuring it was too dangerous. They forgot to take mine though, even though I explicitly reminded them that there was another bar they didn't take.

The last thing we did inside the pool was playing chicken. We would constantly change our pairs around and it was super super fun.

Here is mee and vladimir050 against ar_paixaos19 and _rey, while LoboLobo watches. He also fought at some point.

I was feeling dizzy from all the fighting to the death, so we all got out of the pool.

We played yet another card game called "Burro" with a whole lot of people I do not know the cf handles of. I was really bad at it but luckily _rey was worse so I didn't instantly lose every time. This continued until the sun started rising.

Everyone was tired, there were setters sleeping at the pool area, and we have the idea of going to a random person's room in the highest floor at the hotel so we could watch the dawn of the final day.

It was beaultiful.

We split up, everyone is sleepy as fuck, some people have to get their things ready so they can go back home. However, 3 people know they got something left to do.

On our bus rides to UNICAMP, we noticed that there was a store called "Marcelo Caminhões", or "Marcelo Trucks". One of the IMO gold medallists from Brazil is also called Marcelo. We probably wouldn't have done it we werent almost 24h without sleep, but mee, ar_paixaos19 and LoboLobo may have left the hotel while no one was looking, even though vladimir050 and _rey told us not to do it, wandered onto the street for about 10 minutes, took a selfie with that store in the back, and then returned to the hotel just to get scolded by one of our most laid back teachers, arthur.nascimento.

I was sure to send the photo to Marcelo tho.

"Fucking hell, LMAOOOO. Yall sick in the head." — Marcelo "pastel" Machado Lage, IMO 2022 golder

Closing Remarks

This was a week I will never forget to the rest of my life. A week with lots of ups and downs meeting incredible people and having lots of fun. For the past 9-ish hours I've put my heart and soul into this blog, reminding myself of every little memory I amassed during this event. I have only thanks to give to everyone responsible for making the TST such a wonderful experience, despite all the difficulties, technical problems, financial problems, scheduling problems and etc.

As a send-off for this blog, here is a photo of mee finally sleeping while waiting for breakfast to open, after sending the photo to Marcelo. Enjoy!

Hello codeforces!

Because of weird scheduling issues, the brazilian TST is normally made at december of the year before IOI, different from the rest of the countries. So, today was the last day of TST and after 4 days of contests we have our team settled:

From left to right, we have:

• Leonardo Valente Nascimento (defnotmee)
• Rafael Nascimento Soares (Deepesson)
• Arthur Lobo Leite Lopes (LoboLobo)
• Pedro Suyama Leston Rey (_rey)

In case youre curious, here is a screenshot of the scoreboard so you can see how everyone went.

We were quite comfortably above 5th place in the end, but i had a headache on the first day so i wasn't even top 4 on it. The problems were also really good, as they typically are (even though i can't say the same about the test cases :P).

This team is particularly strong (for Brazil at least) and I'm pretty happy about it.

Leonardo (definitelynotmee)

All I can say about myself is that I was in IOI 2022 and got 57th (silver medal). I took a bit of a break from cp since i came back from Indonesia, but now with school ending I'll have basically infinite time to practice cp.

Rafael (Deepesson)

Heuristics monster. Notably, in a training camp, he passed a problem no one else did with simulated annealing (or as he calls it, "the forge"). He also went to IOI with me, and we got the best placings out of the brazilians on it.

Arthur (LoboLobo)

He's a second year high schooler that is coming on strong, surprising everyone by AKing 2 out of the 4 days of the TST. Honestly the one i know the least out of the 4, so I don't know their full potential. Despite that, he's definitely someone to look out for. Also note that he can also go to IOI 2024.

Pedro (pedroslrey)

Perhaps the most interesting out of the 4. He is in 9th grade, so in addition to IOI 2023, he can go to IOI 2024, 2025 and 2026. He's from the same school as me, so I've known him for a while. Last TST he got 11th place, getting just outside of the range to go to CIIC (the iberoamerican competition), but he did a lot of training since that and got into the IOI team.

He also lost his phone in every TST he has been in, definitely a feat to beat.

Closing thoughts

Brazil is starting to get some really solid teams with some really talented people, and with so much time to train, I think we can do well in hungary.

EDIT: forgot to add earlier, but here is a follow-up blog

Hello codeforces! I've come to ask help in a time of great mystery.

I was helping to debug a problem where the code would pass the 2s TL when on a 64-bit compiler but would get confortably under 1s on a 32-bit one when some really bizarre things started to happen.

First, pinning down where the problematic parts were, it turns out this was the thing consuming practically the whole time limit:

set<ll> s;
for (int i(0); i < k; ++i) {
    int pp;
    cin >> pp;
    s.insert(pp);
}

Im not joking. Also k <= 3e5 btw.

It really shouldnt be a big deal, and normally that part should take less than 140ms, but both on C++20 (64) and C++17 (64) make it take from 1900ms to 2000ms.

I made a submission that outputs the time taken to do the input, the inserting, and the ammount of elements in the set; and with that even more weird stuff appears. Look at the result:

142730404

0:
Input Time: 0ms
Insert Time: 0ms
Set Size: 0

50000:
Input Time: 36ms
Insert Time: 38ms
Set Size: 50000

100000:
Input Time: 74ms
Insert Time: 83ms
Set Size: 99904

150000:
Input Time: 566ms
Insert Time: 142ms
Set Size: 99904

200000:
Input Time: 1059ms
Insert Time: 200ms
Set Size: 99904

250000:
Input Time: 1543ms
Insert Time: 244ms
Set Size: 99904

In this test case until the 90000-ish iteration there are distinct elements and after that the input time starts to raise aggressively, while the insert time grows at a basically unaltered pace. Maybe they start repeating a relatively big number, but even then, it goes from 30ms to read 50000 guys to 500ms. It's insane.

If you want, take a look at the version of the output when using 32-bit for comparison (the numbers will actually be a bit inflated because you need to get the timings with std::chrono):

142730436

0:
Input Time: 0ms
Insert Time: 0ms
Set Size: 0

50000:
Input Time: 41ms
Insert Time: 47ms
Set Size: 50000

100000:
Input Time: 82ms
Insert Time: 101ms
Set Size: 99904

150000:
Input Time: 123ms
Insert Time: 151ms
Set Size: 99904

200000:
Input Time: 164ms
Insert Time: 198ms
Set Size: 99904

250000:
Input Time: 204ms
Insert Time: 240ms
Set Size: 99904

Final Input Time: 245ms
Final Insert Time: 285ms
Final Set Size: 99904

Ending thoughts

• The problematic test case is case 6, however case 5 has the same input size and the set ends up with more items (see 142732612). Why is the problem only with test 6???

• If instead of reading a variable and instantly inserting it into the set, you first input an array and then insert it into the set, no tragedy happens (142732784).

• How can the input go so wrong? A 20x slowdown out of nowhere should not be happening.

• Is there a way to get the raw test data from the authors or something similar to see what actually was on test 6 so we can try to replicate it?

• Thanks qwexd for doing nothing.

So, on the last round i wasnt at home, and therefore had to use another person's computer to do the contest. Waking up to close to the start time made me not be able to set up the IDE properly, so I thought "why not just use ideone"?

But what is Ideone anyway?

Well it says its an online compiler, so it must be a great alternative to a text editor to test things locally. However, little did I know that it was, in fact, a trap meticulously crafted by the devil, as I received those kind messages from codeforces:

There are 5 more of these.

Well, let me explain. This is what appears when you go into ideone:

Notice something wrong? Right at the corner of the screen there is a grayed out page called "recent codes", where you can see the recent submissions from people (for absolutely no reason). In fact, any code you post there is available for everyone to see! Such a distinguished feature! The only way to circumvent this is by noticing that that miniscule globe image right below the text box means that the whole world is seeing your solution.

Let's compare it with another site, pastebin. This is what appears when you access it:

Not only is it not a compiler to trick people doing coding competitions, but also its written public instead of an image you have to guess means public, and the public pastes appear on the same page as the one youre typing on, and they dont actually put stuff from people who arent logged on there. Considering logging on there is basically impossible (at least for me), most people are completely safe and happy.

So ok, ideone is bad and made you look like a fool, but why is it evil?

Well, let's find who is behind ideone (aside from the devil of course).

According to https://craft.co/ideone , it's Sphere Research Labs. Sphere... can you guess what it relates to? Yes, Sphere Online Judge, or SPOJ. We don't even have to go as far to confirm its the same company who takes care of both of them, look at the second result on google.

SPOJ itself said it!

And what does spoj have to do with it? See, SPOJ is an online judge, but it has another distinguished feature, it doesnt let you see other people's codes no mather what, which severely hampers the ability to learn coding tricks by looking at good corder's solutions. If the implications are not obvious, I'll let the words of the great brunovsky my own:

That settles it. The Sphere Research Labs are in fact a company design to destroy the lives of coders little by little. Not only do they do the shittiest judge imaginable (SPOJ, that has no one using it but still takes 3 hours to process your code that takes half a second to run, in addition to not having c++17), but at the same time create a trap website (ideone) in such a way that codeforces has to not punish cheaters so harshly, because they can just be someone who used it.

Extra Spice:

Looking at some of the submissions that were plagchecked with mine, we can see some interesting stuff, like this code for A, which was submitted a single minute after mine, and is in fact, completely identical. Not only that, but this freshly created account copied my codes for A, B and C, each of them shortly after i submit into codeforces. It is of my firm belief that this man, along with many others, is actually a bot (which can or cannot be setup by Sphere Research Labs) targetting naive people who trust ideone with their codeforces solutions, making them lose the rating they rightfully earned.

That being said, thanks for coming to my TED talk.

UPDATE:

Guys, good has won this battle. Sphere Research Labs has commented on this post and as of now, private is now the default version of ideone.

As means of reconciliation for the mean comments I've made about them, ideone will be now my go to online compiler, as well as the place i will be pasting code when i need to send someone.

I would like to thank everybody that helped on this cause and gave me contribution, we wouldnt have done this without your help. Im genuinely super happy. Have a great night everyone, history has been made today!