Dear IOI Community,

The Call for Tasks for the International Olympiad in Informatics (IOI) 2025 is now open. IOI is the most prestigious programming contest for pre-university students. The Scientific Committees of IOI 2025 invite everyone (other than potential IOI 2025 contestants) to submit their tasks to the IOI 2025 Call for Tasks. We welcome any tasks of various difficulty levels, and we are actively encouraging submissions of easy problems. The deadline for the call for tasks is 29 December 2024.

The link for the call for tasks is: https://ioi2025.bo/call-for-tasks.html

For any questions please reach out to [email protected].

Best Regards,

Agustín Santiago Gutiérrez

ISC Chair

👋 Salam, Codeforces!

We are thrilled to invite you to the Rayan Programming Contest 2024 - Selection (Codeforces Round, Div. 1 + Div. 2).

The Selection Round will be a rated contest for Div. 1 + Div. 2, taking place on Nov/30/2024 17:35 (Moscow time). The problems for this round were crafted and prepared by ArshiaDadras, MohammadParsaElahimanesh, AmShZ, AmirrzwM, and Keshi.

The top 60 trusted participants (with a maximum of three from each country) will qualify for the onsite Final Round in Tehran, in Spring 2025. An additional quota is reserved for the host country. Hotel accommodation and meals will be provided to all finalists. More details about the final contest will be available on the Rayan website.

🏆 Selection Round Prizes:

• The top 50 participants will receive T-shirts.
• Additionally, 50 random participants from ranks 51-1000 will also receive T-shirts.

🏅 Final Round Prizes:

• 1st place: $15,000 💵
• 2nd place: $10,000 💵
• 3rd place: $5,000 💵
• 4th–6th places: $2,000 each
• 7th–10th places: $1,000 each

🙏 Special Thanks:

We would like to extend our deepest gratitude to:

• MikeMirzayanov for enabling this event through the amazing Codeforces platform.
• The one and only KAN for his invaluable support in hosting the round.
• Dear TheScrasse for his dedicated coordination efforts and lots of discussions about the problems and rejecting a big chunk of our problems for Problem C.
• Our testers who tested and provided invaluable feedback to improve the problems: peti1234 for being our LGM (VIP) tester, wyrqwq for his great ideas and ignoring his school midterms to test the problems, Error_Yuan for helping us and picking on tough problems for no reason, Hyperbolic, DylanSmith, Clan328, powervic08, CepryH9, mispertion20, PineapplesOnPizza, vyshniak.n, ErrorAssassin, nicolasalba, naniim, estoy-re-sebado, mika_uwu, rulerofcakes, AkiLotus, sleepwalking643, Leonardo_Paes, RockSnow, waidenf, and newb_programmer.
• Prof. Hamid Zarrabi Zadeh and Prof. Mohammad Ali Abam, whose leadership and organizational efforts make this event a reality. Thanks to their vision, Rayan is becoming one of the largest competitive programming contests in terms of prizes (and soon participants!).
• You for participating and getting positive delta (and maybe the final prize in the next year 💸😉).

The score distribution will be shared closer to the contest date.

We look forward to seeing you both online and onsite!

Good Luck & Have Fun! 🎉

Needed 87 to be expert guess how much I got...It's so funny :-)

Meta Hacker Cup Shirts

Hacker Cup shirts are back this year! If you placed in the top 2000 of Round 2, you'll have a shirt available on your Hacker Cup Profile page. If you placed in the top 200 of Round 3, you'll win a shirt with a top-200 badge on the sleeve, instead of the normal shirt.

You must claim your shirt by December 13th. We will not be shipping shirts after the 13th.

Due to regulations, Meta is also not able to support prize shipments to the following countries at this time:

Shirts shipped to addresses in the United States should be delivered within 1 week of being claimed. Shirts delivered to addresses outside the United States may take up to 3 weeks to be delivered.

Links to track your shipment can be found on your profile page once your shirt is shipped. Please note that you must have to claim your shirt from our vendor's website using the code in your profile. Their website looks like this:

I have participated in the Meta Hacker Cup for four consecutive years: 2021, 2022, 2023, and 2024. After receiving the T-shirt today, I would like to share my experiences and progress.

2021: A newbie want a T shirt

This year, I was a complete newbie. The first two rounds lasted over 24 hours, which gave me more time to solve the problems, so my rank looked good. However, Round 2 was only 3 hours long, and it turned out to be a complete disaster for me.

I got stuck on the first problem and doubted my solution repeatedly. Although I finally solved it 30 minutes before the contest ended, I had no time left for the other problems. In the end, I only solved one problem and ranked 2700+, which meant I didn’t even qualify for a T-shirt. I shared my result with some Meta HR representatives, but they didn’t respond. I applied to several positions at Meta, but my resume was rejected.

I also participated in the Google Code Jam Round 2 and ranked 1000+, but I failed to qualify for Round 3.

2022: Finally I get a T shirt

This year, I performed much better. I finally made it to Google Code Jam Round 3! For the Hacker Cup, in Round 2, there were six problems, and I was able to solve two this time. I made it to the top 1000 and won a T-shirt for the first time.

However, after the contest, I realized I could have done better. With just 30 more minutes, I could have solved A2, and the probability problem wasn’t too hard either. If I had solved just one more problem, there was a great chance I could have qualified for Round 3.

2023: Thank you Meta for keeping this competition alive

This year has not been a smooth one.

First, I wanted to challenge myself with Google Code Jam again because, although I qualified for Round 3 last year, I performed poorly and ranked near the bottom. However, Google canceled the contest this year, which left me with a very bad impression of the company. To make matters worse, TopCoder also canceled its contest. I thought Meta might follow suit, but to my surprise, they decided to keep the Hacker Cup running.

This year, I must admit that I didn’t perform as well as I had hoped, especially in Round 1. For the first time, I ended up with a four-digit rank in that round. My performance in Round 2 was a little better. After struggling with Problem C (Wiki Race) for nearly an hour, I discovered that Problem D was much easier. If I had focused on Problem D earlier, I might have qualified for Round 3. Still, I managed to secure a spot in the top 1000 and earn a T-shirt. The T-shirt is very comfortable, and I’m wearing it even now.

On a positive note, I was contacted by an HR representative from Meta. She said she was impressed by my performance and wanted to talk to me. Although I haven’t received any follow-up or rejection letter since then, it feels like a good start.

2024: Finally make it for round 3

This year, GPT has become much more advanced, and Meta introduced an AI track, which made the competition even more interesting. Additionally, the pretests in this contest were noticeably weaker. My guess is that this might be an attempt to prevent AI-assisted cheating.

My performance this year was much better than in previous years. In Round 1, I made a false assumption and received a Wrong Answer (WA) on Problem D. In Round 2, I missed a corner case on Problem B and got another WA. However, this has been my best performance yet, as I ranked in the top 500 for all three rounds and historically qualified for Round 3! My goal this year was to win the coveted "Top 200 Badge" T-shirt.

Three days before Round 3, I mocked the 2023 Round 3 and achieved a rank of around 140–150, which gave me confidence that I had a real chance. Then, on Saturday, Round 3 began.

The Contest Problem A was very tricky. Initially, I misread it as "minimum area," so I wrote a sliding window solution within 30 minutes. However, I soon realized my understanding was wrong—it was actually about "maximum area." This forced me to start over from scratch.

I also noticed that the validation test set didn’t include the k=3 case. My judgment was that Problem A would likely have a high FST rate. To ensure my solution was robust, I spent more than two hours considering numerous corner cases, writing a brute-force solution, and using a random generator to create small test cases for debugging. After extensive testing, I was confident in my solution and submitted it.

When I moved on to Problem B, I realized it was much easier than Problem A. I regretted spending so much time on A, as I only had 30 minutes left. Unfortunately, I wasn’t able to finish B in time. In the end, I only solved one problem and ranked 296, falling short of my goal of earning the "Top 200 Badge" T-shirt.

Reflection The main reason I failed was that I was overly cautious about system test failures, which made me spend too much time on Problem A. While I did secure my 17 points on A, I now realize that even if I had failed the system test on A, solving B quickly could have still placed me in the top 200. Problem C was also solvable for me, as I am quite good with probability, but I didn’t even get to attempt it due to my time allocation.

2025: Can I have a top-200 badge T-shirt this time?

To be continued ....

Finally, I would like to thank Meta. Although Meta has rejected my resume for SDE and MLE positions 12 times, the company still provides us with a great contest (not cancel it like GCJ), at least for fun.

The IOI is designed for high school students, and the ICPC is for college students. For someone like me—a post-PhD graduate—there are almost no public contests in the United States. Despite the unique format of the Hacker Cup, which many of us are not fully accustomed to, I still hope this contest continues in the future.

At this point, I no longer expect HR to give me a chance for an interview, as it feels meaningless. Competitive programming itself is fun, and that’s enough for me. Besides, you can see my progress from 2021 to 2024—it has been steadily improving. That alone is a great achievement.

We invite you to participate in CodeChef’s Starters 161, this Wednesday, 20th November, rated for all. The contest duration will be 2.5 hours.

Time: 8:00 PM — 10:30 PM IST

Joining us on the problem setting panel are:

• Contest Admin, Statement Verifier and Text Editorialist: Nishank IceKnight1093 Suresh

• Tester: Takuki tabr Kurokawa

• Setters: Nishank IceKnight1093 Suresh, Cozma tibinyte Tiberiu-Stefan, KaiSuoShuTong.

Special thanks to satyam343 for discussing several problem ideas with me.

Written editorials will be available for all on discuss.codechef.com. Pro users can find the editorials directly on the problem pages after the contest. The video editorials of the problems will be available only to Pro users.

Also, if you have some original and engaging problem ideas, and you’re interested in them being used in CodeChef's contests, you can share them here.

Problem Distribution:

• Division 1: 7 problems, one is a subtask

• Division 2: 7 problems

• Division 3: 8 problems

• Division 4: 8 problems

Hope to see you participating.
Good luck!

Congrats to the top 5 in Div. 1!

1. potato167

2. noimi

3. SSerxhs

4. risujiroh (only participant to solve "Easy Constructive Problem"!)

5. RNS_JK

We will hold AtCoder Beginner Contest 381.

• Contest URL: https://atcoder.jp/contests/abc381
• Start Time: http://www.timeanddate.com/worldclock/fixedtime.html?iso=20241122T2100&p1=248
• Duration: 100 minutes
• Writer: Nyaan, math957963, PCTprobability
• Tester: MtSaka, sounansya
• Rated range: ~ 1999
• The point values: 150-150-300-425-500-525-675

We are looking forward to your participation!

Hello, CodeForces!

After the victory in ICPC 2024 Taichung Regional, I guess that many people think like as follows:

Team Screenwalkers will advance to the ICPC 2025 World Finals. Even if another team in The University of Tokyo gets the first place in another regional, Screenwalkers can participate in at least ICPC 2025 Asia Pacific Championship.

However, it is not true, because of the internal rules in the University of Tokyo. In The University of Tokyo, the special "Japan-prioritize Rules" exists — that is, if two different teams got the first place in regionals, those who won in Japan regional (which will be held in Yokohama city) will automatically win the tickets of ICPC 2025 World Finals.

Anyway, after the national first round in July, the following 3 teams from The University of Tokyo will advance to Yokohama regional. Therefore, the scenarios in the following figure can happen.

• Screenwalkers (E869120, square1001, Kodaman)
• SPJ
• HHIJKT

If you are curious about which UTokyo team will go to ICPC WF, you should notice that "Yokohama will decide everything". Note that Yokohama regional will held on December 21-22, 2024.

just curious

We are excited to invite you to TLX Regular Open Contest #41!

Key details:

• Contest links: TLX

• Time: 24th November 2024, 16:05 UTC+7

• Writers: SphericalCow

• Duration: 2 hours

• Problems: 7

• Scoring distribution: TBA

We would like to thank:

• yz_, steven.novaryo for the help with the early stages in coordination.
• aufannn, rama_pang for testing the problems and giving meticulous feedback.
• fushar for the outstanding TLX platform.

Please register for the contest and we encourage you to read all problems! Enjoy the contest!