I've checked today is not April 1st.

(source: 12 Days of OpenAI: Day 12 https://www.youtube.com/watch?v=SKBG1sqdyIU)

Hi, everyone.

The first stage of the IOI 2025 China Team Selection began yesterday. The top 50 participants from the 2024 National Olympiad in Informatics (NOI) will compete for a spot on the Chinese national team for IOI 2025.

The rule of selecting CHN team this year:

• Homework (10%): also known as mutual tests, where the students were asked to prepare a task (5%), and participate in the contests made by other students (5%)
• First stage (CTT; 54%; Dec 3, 2024 — Dec 5, 2024): three contests in classic olympiad format, where each contest worthes 18% of the score. Top 30 participants will advance to the final stage.
• Final stage (CTS; 36%; Jan 20, 2025 — Jan 22, 2025): two contests in classic olympiad format, where each contest worthes 18% of the score.

The current scoreboard can be found here.

Past problems of the China IOI Team Selections can be found here (first stage and final stage). I will upload all the tasks once they can be publicly shared.

The 2025 Universal Cup Finals will be held on February 19-24, 2025, in Dongguan, China.

Starting on November 1st, based on the results of the 2023 ~ 2024 Universal Cup Online Stages and The 2nd Universal Cup Semifinals, the Universal Cup Scientific Committee will start promoting teams to the Finals according to this protocol. Invitations will be delivered through email.

The contest schedule is as follows:

Schedule

If you have any related questions, please email us at [email protected].

Sponsored by

Hello, Codeforces!

The Contest Session of The 2024 ICPC World Finals Astana will start soon. We (Qingyu, jiangly, chenjb) the members of the Universal Cup, along with skip2004, QAQAutoMaton, and HaitangSuki, will give the official Chinese live stream on both ICPCLive YouTube Channel and my Bilibili channel.

There will be another stream on jiangly’s bilibili channel with the participation of the mirror contest by the team jiangly, Rewinding, and Kevin114514.

We look forward to seeing you on the live stream!

Hello everyone, we are happy to announce that the 3rd Universal Cup has started officially. Universal Cup is an organization dedicated to offering training resources for competitive programming teams. In the previous season, over 900 teams from more than 500 affiliations all over the world, registered and participated in a total of 28 stages, encompassing contests from Asia, Europe, and America. We also want to express our gratitude to our sponsor Huawei.

- Semifinal and Summer Summit

As announced before (Link), we will host the 2nd Universal Cup Semifinal on June 23, 2024. The contest will start at 17:00 (UTC +8) and end at 22:00 (UTC +8).

Any Universal Cup registered team can participate. If you are new here, please register following the instructions on Registration.

Besides competing to advance to the UCup Finals, sponsored by Huawei, we also prepare prizes for teams in the top 10 (excluding onsite teams in the Summer Summit) . The prize details are as follows (may be replaced by products of similar value when processing):

After the online semifinal, we will host a stream of all invited teams competing in the semifinal contest at the Summer Summit event in Cancun, along with problem analysis. The stream will start at 22:00 (UTC +8) and end at 03:00 (UTC +8).

• English: YouTube (through tourist's account!)

• Chinese: Bilibili (through jiangly's account!)

Here is a list of teams that will be competing onsite:

We also prepare prizes for this onsite competition:

- 3rd Season Online Stage

As usual, this season's main activity is our online stage, where we hold weekly mirror contests. Please refer to our website https://ucup.ac/ for previous results. If you are interested in participation, please register following the instructions on Registration.

The online stage rule is still the same as last season:

- 08:00 (UTC +8) on Saturday ~ 13:00 (UTC +8) on Saturday
- 10:00 (UTC +8) on Saturday ~ 15:00 (UTC +8) on Saturday
- 13:00 (UTC +8) on Saturday ~ 18:00 (UTC +8) on Saturday
- 16:00 (UTC +8) on Saturday ~ 21:00 (UTC +8) on Saturday
- 19:00 (UTC +8) on Saturday ~ 24:00 (UTC +8) on Saturday
- 21:00 (UTC +8) on Saturday ~ 02:00 (UTC +8) on Sunday
- 23:00 (UTC +8) on Saturday ~ 04:00 (UTC +8) on Sunday
- 02:00 (UTC +8) on Sunday ~ 07:00 (UTC +8) on Sunday

To provide more convenience, we implement a few more features on the system, including team composition, extra time window application, etc:

Lastly, we would like to express our gratitude to MikeMirzayanov for letting us advertise Universal Cup in Codeforces and providing the great platform Codeforces and Polygon to help prepare contests. We are also very thankful to all contest stage setters for your support of the Universal Cup. If any setter would like to propose a stage, please feel free to contact us.

Universal Cup Committee:

• Jingbang chenjb Chen
• Yuhao jqdai0815 Du
• Lingyu jiangly Jiang
• Yaowei Sugar_fan Lyu
• Qingyu Qingyu Shi
• Yaohui quailty Zeng

Hello everyone!

We are thrilled to invite you to The 2nd Universal Cup, Stage 26: Latin America, taking place on March 23rd, 2024.

This stage is based on The 2024 ICPC Latin America Championship, which is the super-regional of the ICPC in the Latin America Region.

Task setters and testers: paulocezar, elsantodel90, mnaeraxr, ASdeL, VLamarca, Lebossle, WeakestTopology, arthur.nascimento, cabessa, jpmarin, MarcosK, MateoCV, wellvolks, crbonilha, kobus, pablobce, and MickyOr.

We are looking forward to your participation!

Hello everyone!

We are thrilled to invite you to The 2nd Universal Cup, Stage 23: Shanghai, taking place on February 17th, 2024.

This stage is based on The 2023 ICPC Asia East Continent Final Contest, which is the last contest in the Asia EC Region in this season. 280 official teams participated in the onsite contest competed for the last WF slots of the season.

I would like to thank all task writers for their efforts on preparing the contest. They are dXqwq, jqdai0815, Kubic, littlelittlehorse, MagicalFlower, Qingyu, QuietBeautifulThoughts, unputdownable, and xyz2606.

Also a big thank you to all the people who tested the contest and gave their valuable advice: __ZMF__, antontrygubO_o, chenjb, cmll02, dXqwq, gisp_zjz, heno239, hyforces, JianfengZhu, Lynkcat, noshi91, oipotato, orzdevinwang, potato167, PubabaOnO, Qiulyqwq, RedreamMer, Rewinding, Roundgod, Subconscious, tatyam, TLE, and zaozao_zmx1.

We are looking forward to your participation!

Greetings!

We are thrilled to invite you to The 2nd Universal Cup, Stage 17: Jinan, taking place on January 6th, 2024.

The contest is an official ICPC Regional Contest — The 2023 ICPC Asia Jinan Regional Contest. Just like Nanjing and many other Chinese Regionals, there is finally an onsite event after three years of the online contest.

As the chief judge for the second time in an ICPC regional contest, I am proud of the hard work and dedication that has gone into preparing this contest. We hope it provides an enriching and enjoyable experience for all participants.

（You may find more photos here)

The authors for preparing the contests: chenjb, Elegia, J.T.J.L., Kubic, Subconscious, TsReaper, Qingyu, quailty, zimpha

The testers for their valuable advice: djq_cpp, Rewinding, gisp_zjz, hehezhou, Hezhu, jiangshibiao, Lweb, lwn_16, lxlxl, oipotato, p_b_p_b, qazswedx2, Rebelz, RobeZH, Roundgod, shb123, skip2004, Suika_predator, TLE, triple__a, Warriors_fsy, YaoBIG

We are looking forward to your participation!

Hello! I'm happy to announce The 2nd Universal Cup. Stage 11: Nanjing, which will be held on November 25th, 2023.

This contest is an official ICPC Regional Contest — The 2023 ICPC Asia Nanjing Regional Contest. The contest is prepared by the SUA Programming Contest Problem Setter Team, which was the fourth time for us to prepare the Nanjing Regional Contest. Due to the covid pandemic, the previous three Nanjing regionals were held online. As the pandemic has come to an end, we can finally gather in NUAA to participate in this wonderful contest.

This is also my first time as a chief judge in an ICPC regional contest. Great thanks to the host school (Nanjing University of Aeronautics and Astronautics) for preparing the Regional, and the hard work done by all staff and volunteers for this contest.

The authors for preparing the contests: chenjb, jiangshibiao, Joyemang, J.T.J.L., lwn_16, lxlxl, oipotato, Qingyu, shb123, Subconscious, Suika_predator, TsReaper, zimpha.

The testers for their valuable advice: abc473848880, alexlikemath007, djq_cpp, duality, edchen, skip2004, gisp_zjz, Gromah, HaccerKat, hehezhou, hyforces, kevin, KeyID, lunchbox, Minhho2005, noshi91, nothing100, Orenji.Sora, oursaco, potato167, qazswedx2, RandomKami, RobeZH, Roundgod, smax, tatyam, TLE, triple__a, UESTC_Nocturne, willy108, and YaoBIG.

The 11th Stage of the Universal Cup, Nanjing, will be based on this contest. You can participate in the contest from Nov 24 to Nov 26. Note that we have added more time windows to avoid the conflicts with the ICPC Asia Pacific Regional contests.

We are looking forward to your participation!

In the interest of contributing to the community and bridging the gap between competitive programming and industry, we are happy to announce that in the future, Universal Cup will be cooperating with Huawei in many areas.

Huawei will support Universal Cup in future seasons. In the meantime, we will explore the cutting-edge challenges from the industry together as an additional activity during the Universal Cup season. These events might also serve as parts of other official programming competitions. Moreover, we intend to run some interviews and other events together, providing opportunities for communication between participants and the industry. We also hope that in the future, we can invite the top competitive programming teams to compete in the Universal Cup Onsite Final. It will definitely be one of the best events ever! Please stay tuned and support Universal Cup!

About Universal Cup

The Universal Cup is a non-profit organization dedicated to offering training resources for competitive programming teams. Up to now, there are more than 2600 teams from all over the world registering for Universal Cup. With the permission of contest setters and without involving copyright disputes, the Universal Cup will hold mirror contests for some undisclosed competition sets. We will simulate the actual situation in the competition, executing the board freeze in the last hour. At the same time, we will provide an overall rating board, which will help the team to make a reasonable assessment of itself.

If you want to find a more detailed introduction or participate in this season, please visit: https://ucup.ac

About Huawei

Founded in 1987, Huawei is a leading global provider of information and communications technology (ICT) infrastructure and smart devices. We have 207,000 employees and we operate in more than 170 countries and regions, serving more than three billion people around the world.

Our vision and mission is to bring digital to every person, home and organization for a fully connected, intelligent world. To this end, we will work towards ubiquitous connectivity and inclusive network access, laying the foundation for an intelligent world, providing diversified computing power where you need it, when you need it, to bring cloud and intelligence to all four corners of the earth; build digital platforms to help all industries and organizations become more agile, efficient, and dynamic; and redefine user experience with AI, making it smarter and more personalized for people in all aspects of their life, whether they're at home, on the go, in the office, having fun, or working out.

For more information, please visit Huawei online at: https://www.linkedin.com/company/Huawei, http://www.twitter.com/Huawei, http://www.facebook.com/Huawei, http://www.youtube.com/Huawei

The 17th round of the first Universal Cup is happening this week. The contest is based on the Final Contest of the China Collegiate Programming Contest (中国大学生程序设计竞赛, CCPC), which took place in Guangzhou on May 14th, 2023. Around 130 teams joined the on-site round.

Onsite Judges: jqdai0815, Qingyu

Tasks Authors: jqdai0815, djq_cpp, MagicalFlower, gyh20, ix35, Rebelz, Qingyu, Yakumo_Ran

Testers: AcFunction, changruinian2020, cnnfls_csy, Crystally, PubabaOnO, MagicalFlower, gyh20, He_Ren, Sugar_fan, kgqy, llzer, loveye , lqx2005, MagicNiu, Mr_Eight, orzdevinwang, qazswedx2, rsy, Starch, sunzh, ttklwxx, wangziji, Z-301

As always, there are three time windows for you to join:

• May 20th 13:00 — 18:00 (UTC +8)
• May 20th 19:00 — 24:00 (UTC +8)
• May 21st 02:00 — 07:00 (UTC +8)

Please note that you can see two scoreboards in DOMjudge. The 'Local Scoreboard' shows the standings ONLY IN THE CURRENT TIME WINDOW. And the 'Combined Scoreboard' shows all participants, including the onsite participants, and the cup participants in the previous time windows.

Contest link: https://domjudge.qoj.ac/

Universal Cup Scoreboard: https://qoj.ac/ucup/scoreboard

About Universal Cup:

Universal Cup is a non-profit organization dedicated to providing trainings for competitive programming teams. Up to now, there are more than 600 teams from all over the world registering for Universal Cup.

A more detailed introduction: https://codeforces.net/blog/entry/111672

Register a new team: https://ucup.ac/register (the registration request will be processed before each stage)

Results of the past stages: https://ucup.ac/results

Terms: https://ucup.ac/terms

Ratings: https://ucup.ac/rating

Hello Codeforces! The 6th Stage of the 1st Universal Cup is coming. It will be held from Mar 4th to 5th.

The contest is based on an official ICPC Asia Pacific regional contest. It has been used in the 2022 ICPC Asia Taoyuan Regional Programming Contest, which was held on November 19, 2022 — November 21, 2022. Thanks to the judges and authors for preparing this great contest and sharing with us as a Universal Cup Stage.

As usual, we have three time windows for participating. You can participate in the contest in the following three time windows:

• Mar 4th 13:00 — 18:00 (UTC +8)
• Mar 4th 19:00 — 24:00 (UTC +8)
• Mar 5th 02:00 — 07:00 (UTC +8)

Please note that you can see two scoreboards in DOMjudge. The 'Local Scoreboard' shows the standings ONLY IN THE CURRENT TIME WINDOW. And the 'Combined Scoreboard' shows all participants, including the onsite participants, and the cup participants in the previous time windows.

Contest link: https://domjudge.qoj.ac/

Universal Cup Scoreboard: https://qoj.ac/ucup/scoreboard

About Universal Cup:

Universal Cup is a non-profit organization dedicated to providing trainings for competitive programming teams. Up to now, there are more than 500 teams from all over the world registering for Universal Cup.

A more detailed introduction: https://codeforces.net/blog/entry/111672

Register a new team: https://ucup.ac/register (the registration request will be processed before each stage)

Results of the past stages: https://ucup.ac/results

Terms: https://ucup.ac/terms

Ratings: https://ucup.ac/rating

Hello everyone! The 3rd Stage of the 1st Universal Cup: Poland, will be held on Feb 11th, 2023.

The contest was used in the Akademickie Mistrzostwa Polski w Programowaniu Zespołowym (AMPPZ) 2022, which was hosted by Jagiellonian University.

Authors: paladin, krismaz, Krzysztof Kleiner, Daniel Goc, Kasia, kpw29, Michał Woźny

Special thanks to kostka, who coordinated the contest and gave us a huge help for setting the problems to make it possible as a Universal Cup stage. And thanks to Lech Duraj, the head of the jury of the AMPPZ, provides the contest materials and helps us to use them.

The contest will start soon. You can participate in the contest in the following three time windows:

• Feb 11th 13:00 — 18:00 (UTC +8)
• Feb 11th 19:00 — 24:00 (UTC +8)
• Feb 12th 02:00 — 07:00 (UTC +8)

Please note that you can see two scoreboards in DOMjudge. The 'Local Scoreboard' shows the standings ONLY IN THE CURRENT TIME WINDOW. And the 'Combined Scoreboard' shows all participants, including the onsite participants, and the cup participants in the previous time windows.

Contest link: https://domjudge.qoj.ac/

Regional Scoreboard: https://amppz.tcs.uj.edu.pl/ranking/

Universal Cup Scoreboard: https://qoj.ac/ucup/scoreboard

About Universal Cup:

Universal Cup is a non-profit organization dedicated to providing trainings for competitive programming teams. Up to now, there are more than 200 teams from all over the world registering for Universal Cup.

A more detailed introduction: https://codeforces.net/blog/entry/111672

Register a new team: https://ucup.ac/register

How to solve task C and G?

Since I didn't find a place to discuss the CCO problems, I decided to post this blog.

How to solve Day 2 Problem 3 (Good Game)?

Let's discuss the problems here.

How to solve H. (Hoshi Sudoku) and I. (Imbalance)?

Let's discuss the tasks here.

How to solve problem B?

It seems that the Baltic Olympiad in Informatics (BOI) 2022 is taking place.

Since I didn't find any announcement, will there be a mirror contest this year?

Let's discuss problems here.

How did you solve problem L?

How to solve Problem 7, 10? Is there any tutorial available?

Could not find an official announcement, let's discuss problems here.

As we know, USACO is a competitive programming contest primarily for secondary school students in the US. It offers a large collection of excellent problems, from the easy to the difficult. Many of the problems are educational and worthwhile as training material.

However, the official website only offers problems from as early as 2011, and older problems are hard to find. Some of the Online Judges, such as POJ, contain some of the problems, but they are not properly filed together, and it's difficult to find the corresponding solution and test data.

In this post, I will try to list all the USACO materials that I have found so far. Most of the materials come from some old websites, and thanks to the efforts of web.archive.org, we can check out old websites that no longer exist. In addition, many of the problems were used as training materials in the training of Chinese IOI teams about 20 years ago. These materials have been preserved and are available through some Chinese websites.

It is important to note that since some of the materials are from a single source, I cannot confirm that the content is the original one. Also this list is not complete, there are still a lot materials I could not find. If anyone has these materials and would like to share it, please leave it in the comments section.

USACO 2021~2022

USACO 2020~2021

USACO 2019~2020

USACO 2018~2019

USACO 2017~2018

USACO 2016~2017

USACO 2015~2016

USACO 2014~2015

USACO 2013~2014

USACO 2012~2013

USACO 2011~2012

USACO 2010~2011

USACO 2009~2010

USACO 2008~2009

USACO 2007~2008

USACO 2006~2007

USACO 2005~2006

USACO 2004~2005

USACO 2003~2004

USACO 2002~2003

USACO 2001~2002

USACO 2000~2001

USACO 1999~2000

USACO 1998~1999

USACO 1997~1998

USACO 1996~1997

USACO 1992~1996

Let's discuss problems here.

The opentrains provides a series of high-quality ICPC training contests. However, its contest list is not complete(then it is difficult in finding some contests), and we cannot know if the contest has an editorial until we finish it. Therefore I made a list containing almost all of the contest materials, including contest id, statements, solutions and editorials. I don't know whether these materials can be made public (may affect their training value), so I only provided their corresponding links in opentrains in the table.

The link for Statements, Solutions and Editorials is in the format of http://opentrains.snarknews.info/~ejudge/index.cgi?solarc2=CONTEST_ID&sid=SESSION_ID. You can save the entire page and replace the field SID_HERE in the page with yours. Your SESSION_ID can be obtained from the URL that you jumped to after logging in at http://opentrains.snarknews.info.

For most of the Open Cup and Petrozavodsk contests, you can find the upsolve link in zimpha's posts(here and here). For other contests, I provided some upsolve links that do not require private logins.

You can find the list here, and I hope it will be helpful to you.

GP of Beijing is finished now. How to solve H(Nonsense) and I(Number Theory)?