Because of the Codeforces Round 273 (Div. 2) the training contest 2014-2015 CT S02E06: Codeforces Trainings Season 2 Episode 6 - 2007 Benelux Algorithm Programming Contest (BAPC 2007) will be moved one day forward.

Welcome to 2014-2015 CT S02E05: Codeforces Trainings Season 2 Episode 5 - 2009-2010 ACM-ICPC, NEERC, Southern Subregional Contest. The training duration is 4.30 hours. It is opened for teams as well as for individual participants. After the end you may use the practice mode to complete problem solving. Also it will be availible as a virtual contest for whose of you who can't take part today. Please, do not cheat. Only fair play!

It is possible that the problems will be too easy for some participants, it is possible that we will add some problems.

Good luck!

Welcome to 2014-2015 CT S02E04: Codeforces Trainings Season 2 Episode 4 (US College Rockethon 2014 + COCI 2008-5 + GCJ Finals 2008 C). The training duration is 4.30 hours. It is opened for teams as well as for individual participants. After the end you may use the practice mode to complete problem solving. Also it will be availible as a virtual contest for whose of you who can't take part today. Please, do not cheat. Only fair play!

It is possible that the problems will be too easy for some participants, it is possible that we will add some problems.

Good luck!

Welcome to 2014-2015 CT S02E03: Codeforces Trainings Season 2 Episode 3 (NCPC 2008 + USACO DEC07 + GCJ 2008 Qual). The training duration is 4.30 hours. It is opened for teams as well as for individual participants. After the end you may use the practice mode to complete problem solving. Also it will be availible as a virtual contest for whose of you who can't take part today. Please, do not cheat. Only fair play!

It is possible that the problems will be too easy for some participants, it is possible that we will add some problems.

Good luck!

Welcome to 2014-2015 CT S02E02: Codeforces Trainings Season 2 Episode 2 (CTU Open 2011 + misc). The training duration is 4.30 hours. It is opened for teams as well as for individual participants. After the end you may use the practice mode to complete problem solving. Also it will be availible as a virtual contest for whose of you who can't take part today. Please, do not cheat. Only fair play!

It is possible that the problems will be too easy for some participants, it is possible that we will add some problems.

Good luck!

Welcome to 2014-2015 CT S02E01: Codeforces Trainings Season 2 Episode 1 (NEERC 99 + misc). The training duration is 4.30 hours. It is opened for teams as well as for individual participants. After the end you may use the practice mode to complete problem solving. Also it will be availible as a virtual contest for whose of you who can't take part today. Please, do not cheat. Only fair play!

It is possible that the problems will be too easy for some participants, it is possible that we will add some problems.

Good luck!

The new season of a collegiate team championship ACM-ICPC is about to start. For example, the registration for the Southern (Saratov) Subregional Contest is already running. I am sure that many participants of the Codeforces rounds will take part in ACM-ICPC this year.

We are launching a series of weekly practice trainings on Codeforces. Naturally, they will be held within Codeforces::Gym. Feel free to participate!

The practice starts on Thursdays at about 12:10 PM (UTC), which is 16:10 Moscow Time. Expected duration is 4-5 hours. We are going to practice using the problems of different contests of the past years. All you need is common sense and observing these simple rules:

• We will not publish the problem source before the practice starts. We want you to solve the problems on your own in a fair competition. If you use somebody else’s code or cheat in any other way, you will be disqualified. If you don’t want to solve on your own, that’s fine, you don’t have to. But spoiling the practice for others is unacceptable.
• Do not discuss the problems till the practice ends.
• We will rarely answer the questions about problems. If you’ve found some obvious bug, please let me know. We will fix the bug and send everybody the note about the fix.
• If you have a coach account (and you do not participate in the practice), we will be grateful for your help.
• Please register for the practice with the people from your team who actually participates in it.
• From time to time, I am going to ask some of the jury of the past contests or coaches from other higher educational institutions to help with preparing or share materials — your understanding and help will be greatly appreciated!
• if you solved the contest problems before just switch to another training or inform us via problem questions form, we will move you to out-of-competition role.

The first contest 2014-2015 CT S02E01: Codeforces Trainings Season 2 Episode 1 (NEERC 99 + misc) takes place on September, 11, at about 12:10 PM (UTC).

I've got challenge from agul and caustique. Challenge accepted!

Challenge thrown to TopCoder employees: rng_58 and ivan.metelsky.

Dear friends, you might have noticed that the VK logo has disappeared from the Codeforces pages and all of a sudden the place got sort of empty and a little bit gloomy. By the way, it happened not because the VK company lost the interest towards Codeforces and programming contests. Not at all. On the countrary, we have great plans to carry out together! We are infinitely grateful to the VK company for the 4 years of help and support.

We are glad to inform you that now a wonderful company called Telegram is going to help Codeforces. The company is founded by Pavel Durov and it united many brilliant developers with a rich olympic past. It is pleasant and important for us to see Codeforces helped by the people who understand programming contests, love them and value the skills of the community members. The Codeforces team is happy to get the opportunity to continue working and promises to continue dazzling you with contests, innovations and improvements.

Mike Mirzayanov and the Codeforces team

Oh yes! Only a few days left before the Championship finals! The teams have already gathered in Yekaterinburg, most of them have registered and are watching a game between Russia and Belgium.

I want to start from some history and remember that the tradition to publish travel notes about Saratov State University's trips to finals started back in 2005. The regular pattern is that almost every year when we made notes, our team won a medal. I won't try my luck, so here are some of the first impressions of this year.

We've introduced API and now we want to test the system before Round 251.

I invite you to take part in Testing Round 10. It starts on usual time, June 3rd. It will be unofficial unrated round.

I tried to pick up the problem to make the round interesting for many of you. Pretests are unusually weak to trigger more hack.

If you see any unexpected behavior or bugs, please inform us via comments.\

Thanks.

After a short delay (but Oscar is given in spring too, huh?) we are pleased to announce the Cormen Medal laureates for 2013. This year, we’ve decided to slightly upgrade nominations again, so this year's Cormen Medal is given in two nominations:

• Best Progress
• Best Problemsetter

Best Progress

The Cormen Medal laureate in this nomination is Scott Wu (scott_wu, USA). Note the sharp upward dive his rating line takes. His achievements in 2013 are not limited by the spectacular dive into the best 10 participants on Codeforces: he got the 5-th place on IOI, won the 2013 season of the USACO contests, got target on TopCoder! We congratulate Scott and wish him many more achievements!

Best Problemsetter

We didn't have to search far and wide for the winner in this nomination. Naturally, the Cormen Medal goes to the most productive and loved by many author of 2013, Sergey Nagin (Sereja, Ukraine). Sergey prepared and conducted 7 rounds (all of them Div1+Div2) on Codeforces. Sergey's problems gained popularity among the Codeforces coders and we will be happy to see his contests again in the future! Sergey has already been awarded by a Medal and an Award Plate in February in Kharkov training camp.

Looks like it's becoming a good tradition. The laureates will be sent a book by Thomas Cormen (Introduction to Algorithms or Algorithms Unlocked), signed by the author.

History

Let us remind you that the Cormen medals have been awarded for the fourth year. tourist (Gennady Korotkievich) became the best participant three years in a row (in all the years when this nomination existed). Alex_KPR (Alexander Kouprin) became the best blogger in both years when this nomination existed. My favourite nomination "Best Problemsetter" was awarded to: natalia (Natalia Bondarenko) in 2010, Ripatti (Artyom Ripatti) in 2011, and witua (Vitaly Gerasimov) in 2012. Besides, in 2012 there was a medal for "Codeforces Spirit of Community 2012", the laureate was Nickolas (Mariia Mykhailova).

https://get.google.com/albumarchive/pwa/114907919772955385569/2014CoderStrike?authuser=0&feat=directlink

Hello,

Once again I'd like to host unusual unrated round. With your help we want to test untypical scoring system and unusual problems.

The contest will start today on 18:30 (UTC). We will add large and bright special link to enter into the contest area. The contest duration is 90 minutes. But it will be easy problems and hope that many participants will solve all of them before the end.

Go to the Contest →

It will be two types of problems: logic puzzles and programming tasks.

A logic puzzle is a task that is designed to be solved by hand (but it is not forbidden to write some helper code to do this). Each logic puzzle consists of one or more tests. Each question can be answered separately from the others. There is a "Submit" button below each test. To answer the question, press "Submit" button. Your answer will be acknowledged and checked after the end of the contest. You can change your answer any number of times – only the last attempt is checked. For the correct answer to the question you will get the number of points which is indicated in the question description.

A programming task is which you usually see in Codeforces rounds. Solutions can be submitted at any time during the contest. A solution is evaluated on a fixed set of tests right after it is submitted. For each passed test, a contestant will get a fixed amount of points. The sum of points for all passed tests is the total points received by the solution. The contestant can submit a solution several times. The contestant will receive points for only one solution per problem. The solution with the maximum amount of points will be chosen.

If a pair of contestants have the same number of points gained in contest time, they will be ordered according to the time (in seconds) of the last submission which gave them an improved positive score.

For each programming task, we will consider only the best submission (or if there are many submissions which are equally correct, the earliest). For logic puzzles, we will judge last submission per test.

In other words, it's always safe to submit a new answer for programming tasks (you can only improve your situation). It is not always safe to do that for logic puzzles – consider carefully whether or not you want to do that (you may replace correct answer with incorrect).

Many thanks to all of you who will help. Waiting for your feedback in comments.

The round will start on 08:00 (UTC) of April, 13. It will be a kind of unusual round because at first for a long time Gerald didn't work much on round. It was prepared by me (how it is interesting to write a round!), Nerevar with the help of Gerald and Fefer_Ivan-а. Maria, many thanks for translations!

It will be classical points: 500 — 1000 — 1500 — 2000 — 2500.

Hi!

I think everybody can remember a case when

Probably everyone remembers in practice a case when after implementation of correct algorithm you receive Wrong Answer. In such a situation, sometimes works: to send solution on another compiler.

Gerald and Nerevar have found severe bug, which gives one more argument to use the rule above.

Look closely, now it will be a miracle! 

Some months ago we've found that YuukaKazami took part in contests using one more account. We've contacted him and he pleaded guilty and deplored about it. That acccount has been banned and YuukaKazami was disallowed to take part in rounds for two months.

Now he can take part and we hope to see him again in standings.

About two days ago Java 8 has been released! It is a great update with many interesting improvements and features. If you do not plan to use new language syntax, probably Java 8 will please you with performance improvements.

I've added Java 8 with options like for other versions of Java: java.exe -Xmx512M -Xss64M -DONLINE_JUDGE=true -Duser.language=en -Duser.region=US -Duser.variant=US -jar %s.

Right now, Java 8 supported in testing mode. Let's try it together on problemset problems.

You may see new features in this code — it sorts lines in non-increasing lexicographical order:

import java.util.*;

public class Main {
    public static void main(String[] args) {
        try (Scanner scanner = new Scanner(System.in)) {
            List<String> lines = new ArrayList<>();
            while (scanner.hasNextLine()) {
                lines.add(scanner.nextLine());
            }
            lines.stream().sorted((a, b) -> b.compareTo(a)).forEach(System.out::println);
        }
    }
}

On 02.03.14 there was a serious technical failure: Codeforces and related infrastructure hard drives have been corrupted. Unfortunately, it turned out that in contrast to all other components, the Codeforces database was not replicated properly. Polygon and Gym files were not injured. However, the Codeforces data has been significantly damaged.

We've rolled back the system to the state on February 7. It will remove 22 days of Codeforces life. Immediate efforts will be directed at the total exclusion of such situations. This is a very serious loss for me personally, which I can only blame myself.

Many thanks for all of you who supported us on a temporary Codeforces page. You helped much to find motivation in this difficult situation.

Currently the Gym is disabled. It will be opened back soon. We will return official contests and gym trainings with problems (but not results).

Data to be recovered:

• official contests with problems (but without results);
• public trainings in Gym;
• non-public trainings in Gym, but we do not know their owners — write me if you've prepared non-public training in Gym (not a mashup).

Sorry again for the inconvenience.

The contest Testing Round 9 is a special contest to test recent Codeforces internal improvements. Please, take part in it to help us to be ready for Codeforces Round 224 (Div. 2).

The Testing Round 9 will be completely unofficial and unrated. We will use problems from some Saratov contests, they will be new for many of you.

If you see any issues in Codeforces behaviour, write a comment here.

Thank you!

UPD. The contest completed. Thanks to all the participants.

Hurry! Only until the 10th of January, you can change your handle! Note that it will be possible to roll back the changes or change the handle again only after a year.

Talking about handles I always reminisce the following story. Once a user wrote me the message: "Please change my handle from I_love_Valya to I_love_Sveta, as I no longer love Valya ..."

Happy New Year!