Hi.

In Spring semester, I conducted a short course titled “Dynamic Programming” in SPbSU. To complete the course, the students solved many training problems, and also prepared their own problem in Polygon.

For the majority of the students, it was the first problem they authored. Nevertheless, the result looks cute. A couple problems went to local contests. From the remaining ones, I composed two trainings and put them on Codeforces. The trainings are set at the following time:

• first: Dynamic Programming, SPbSU 2024, Training 1, starts on Jul/06/2024 11:30 (Moscow time), duration: 3 hours (statements, results, tutorial)
• second: Dynamic Programming, SPbSU 2024, Training 2, starts on Jul/07/2024 11:30 (Moscow time), duration: 3 hours (statements, results, tutorial)

Each training contains both easy and hard problems. The majority of the problems are intended for training. I think orange participants and below will have enough problems for the duration. The problems go in randomized order.

Good luck!

Hello.

I am happy to announce stage 1 of season 3 of Universal Cup: St. Petersburg. It will be held this Saturday, on June 8, 2024. The contest uses the problemset of LIX SPbSU Championship which took place on May 12, 2024.

Problem authors: avm, Burunduk1, Dmitriy.Belichenko, Gassa, Kaban-5, nikgaevoy, Olympic_Bear, orz, tranquility (with Codeforces accounts), and also Anastasiya Grigorieva and Leonid Dyachkov.

Proceed to the Universal Cup site to take part!

Hi!

The next stage of Universal Cup, Run Twice Contest, will happen on December 30-31, 2023. As the name suggests, all problems in the contest are in run-twice format. I am the author of the contest.

Originally, the contest was held in Petrozavodsk Summer Camp 2022. The plan was to hold it later as an Opencup stage, in order to further introduce the format to a wider audience. Alas, Opencup got suspended around that time. Fortunately, sharing it beyond the camp can finally happen now. Thanks go to Qingyu and the other Universal Cup admins!

Hi all!

The main phase of VRt Contest 2019 has ended. In the preliminary standings, five contestants managed to obtain a score of more than 60,000 points. The fight continued to the last day. Who will emerge as the winner after the final testing? We will know after it ends. (Update: results in a separate comment.)

I invite the contestants to share their solution ideas in the comments below, or in separate posts if their writeup is too large for a comment.

Hi all!

From April 30th to May 14th, Codeforces will host VRt Contest: the second contest organized by VeeRoute. VeeRoute is the developer of planning and management software for transportation and multimodal logistics.

Contest participants will have to solve an optimization problem where local optimization is challenging. The task is similar to those that VeeRoute has to solve regularly. Since the format is nothing like a standard Codeforces round, the contest will be unrated.

Participation

Everyone is welcome to take part in the contest. The consest is for individual participation, with no restrictions on age or division.

Prizes

• I place — 75 000 RUB (1155 USD)
• II place — 50 000 RUB (770 USD)
• III place — 25 000 RUB (385 USD)

Additionally, top 25 participants will get a VRt T-shirt.

Good luck to all participants, and have a great contest!

Hi all!

The main phase of Codeforces Marathon Round 2 has ended. In the preliminary standings, contestants Rafbill and hakomo have got very close results, at the same time getting far enough from the next group of contestants. Will they manage to maintain the lead after the final testing, and who will come out on top? We will know in a few hours.

For now, I encourage the contestants to share their solution ideas in the comments below, or in separate posts.

Hi all!

This post is inspired by a question here which asks yosupo how using the D progamming language compares to using C++. I regularly use D where possible in contests (and problemsetting) since 2014, with some success (for example, a program in D brought me victory in AZsPCs: Alphabet City). So I'd like to share my experience. I'll try to focus on stuff which is important in competitive programming.

The general feeling is as follows. You can write in D as in plain C when you need full control. You can also write more like in Python using the powerful standard library. However, D is a compiled language, so in both cases, the performance is similar to C++. Additionally, when the program is written, it is much easier to debug than a similar program in C++.

For an example, let us look at two solutions of a recent problem.

Hi all!

I invite you to take part in Codeforces Marathon Round 2. The contest will start on Tuesday, July 24, 2018 at 15:00 MSK, and will last for 7 days. There will be one problem based on game mechanics of a couple of board games for children. The problem most likely does not have a fast and full solution. So the solutions will be given scores, and the winner will be the one who gets the highest total score.

The contest will be unrated because the problem is considerably different from the problems of rated rounds.

During the time of the contest, the solutions will be checked on examples and preliminary tests. After the contest is over, the final solution of each contestant will be checked on the final test set, and the total score for this test set will determine the final scoreboard. The contest will take place on Codeforces platform and is supported by the Community Of Master Programming at St. Petersburg State University (link in Russian) and 90.01 Group.

The Codeforces platform has seen only few marathons so far. So, if something breaks, don't be upset, just write about it, and we will try to fix it.

Good luck in the contest!

The Codeforces Marathon Round 1 is over (results comment). As the final solutions are being tested, I think many participants will want to share ideas and learn alternative approaches. I'll start with the ideas I tried myself, both successful and not; as I've seen in the submissions, the contestants have more ideas, but I hope they will share themselves. For each of the solutions below, the numbers in square brackets are minimum, mean and maximum score when running on 1000 tests locally. I have to note in advance that the constants and technicalities in the solutions are not considered optimal: the score just shows approximate relation between ideas and may often be improved a bit.

Hi all!

I invite you to take part in Codeforces Marathon Round 1. It is an unrated contest in which the participants will have to solve one problem as best as they can. The problem is presumed not to have a fast full solution. A score is given for each individual test according to the quality of the answer found. The goal is to get the highest total score. The contest will go on for 10 days. The start time is June 12 at 12:00 MSK.

During the main phase of the contest, solutions will be checked on examples and preliminary tests. After the main phase is over, the final solution of each contestant will be checked on the final test set, and the total score for this test set will determine the final scoreboard. The 10 top scoring participants, as well as 10 random participants who achieve a good enough score, will get T-shirts. The contest is supported by Codeforces and the Community Of Master Programming at St. Petersburg State University.

This round is experimental: if something breaks, don't be upset, just write about it, and we will try to fix it.

See you in the contest!

Update 1 (12.06.2016)

You can take part in the contest as a team of two people! Both participants must not be registered as individual participants. If you are already registered but did not take any action in the contest, registration can be canceled at the respective page. Note: as the contest was initially planned for personal participation, if a team wins a T-shirt, it will get only one T-shirt.

Update 2 (19.06.2016)

There are a bit less than three days left till the end of the contest. Clarification: the 10 random T-shirts will be distributed among those who are not in the top 10, but get at least half of the possible score on the final tests (for 1000 tests, the boundary score is 500500).

To the best of my knowledge, Felix did not yet get to the very end of the exam in any of the preliminary tests. Who will help the robot? If you did not yet try, it is easy to start: in the development pack available on Github, there are example solutions in seven programming languages, and also tools to run a solution locally with the interactor.

The final testing of VeeRoute Marathon is completed, the results are final. Congratulations to the winners!

I place, score: 488260.182 — Psyho

II place, score: 465947.075 — Rafbill

III place, score: 455743.464 — T1024

All of them will get their well-deserved reward. Additionally, by the organizer's decision, top 32 contestants will get a T-shirt: they are the contestants whose score is more than 300000. They represent 14 countries (Poland, France, Hungary, Belarus, Romania, Russia, Thailand, Lithuania, Hong Kong, Ukraine, Czech Republic, Sweden, Latvia and China) and used six different programming languages: C++, Java, Scala, Python, D and C#.

While the final testing took place, some of the contestants described their solutions:

• Psyho (1 place): greedy and two phases of simulated annealing;

• Rafbill (2 place): minimum cost bipartite matching: order chains and drivers;

• mugurelionut (7 place): graph on pairs (time, place) and greedy;

• LCM (19 place): greedy.

If you liked the marathon problem, we have good news: the second joint marathon is going to take place in two or three months. However, there's no reason to wait: if you are interested in a job at VeeRoute, fill the form, and the company representatives will contact you.

Speaking for myself, I'd like to thank the Codeforces platform and the company VeeRoute for the opportunity to conduct this contest.

The submission time is over for VeeRoute Marathon. Let us discuss the contest — the problem itself and related stuff — while the final testing takes place. Which solutions work best? Were the problem statement and materials sufficient to start solving, or something was lacking? What tools did you implement yourself?

Hi all!

VeeRoute Marathon starts today: it is a programming competition that is organized by VeeRoute and lasts from February 29 to March 14. We have already posted information about the Marathon here on Codeforces, and now we would like to tell more about its organizer.

VeeRoute is a Russian IT-company that develops solutions for logistics optimization. Even though VeeRoute is a young company, its growth has been very rapid: the staff has doubled in the last few months, and the company is preparing to enter the international markets. There are two offices: in Moscow and Saint-Petersburg. VeeRoute is a very attractive workplace for talented and ambitious programmers, because everyday tasks there are challenging and interesting, and the development department is headed by Andrey Lopatin, a two-time world champion in programming.

VeeRoute’s ambition is to become a world leader in the field of IT solutions for logistics optimization. Every day logistics becomes more and more complex, and the key to new challenges is automatization of logistics processes and its management in real time. VeeRoute follows these trends by creating its own Scheduling & Dispatching platform.

If you get excited about challenging and interesting programming problems, if you are good with algorithms and data structures, then VeeRoute Marathon is for you! Register here: http://mirror.codeforces.com/contests/636.

Participants will have to solve a certain optimization problem, similar to those solved by VeeRoute team daily. Do your best and draw VeeRoute’s attention to your talent! VeeRoute is trying to make the world a better place, and looking for individuals who share the same goals and vision.

Good luck and have a nice contest!

Hi all!

From February 29 to March 14, a contest supported by company VeeRoute will be held on Codeforces. VeeRoute is a young and ambitious IT company which specializes in automation of transportation logistics.

Participants will have to solve a certain optimization problem as best as they can. The problem is similar to the ones that are being solved by VeeRoute daily. As the competition format is very different from a standard Codeforces round, the contest will be unrated.

Participants

We invite everyone who is fond of interesting programming challenges and well-versed in algorithms and data structures. The contest is for individuals. There are no restrictions on age or division.

Prizes

After the final testing is over, the winners will be announced, and the following prizes will be awarded:

• I place — iPhone 6S or Nexus 6P at the winner’s choice.
• II place — any mechanical keyboard by Das Keyboard.
• III place — any board game of the Ticket to Ride series.

Additionally, top 30 contestants will receive a T-shirt with the sponsor’s logo.

Good luck and have a nice contest!