Hello everyone! Codeforces Round #FF(255) is coming soon! We invite you to participate in this round, the round will be held in both divisions.

In this round, the boy DZY appears again! As we all know, he loves many things. This time he also brings us many interesting problems, which are easier than the problems in last round, but he still needs you help. In return, he will present rating to you.

Many thanks to Gerald for giving us much advice and helping us to prepare the round. Also many thanks to MikeMirzayanov, who created such a wonderful platform.

The problem setters are jcvb, jiry_2 and me. This is our first Codeforces round :)

Come and join us in helping DZY again, and you will take the high rating home!

Good luck and have fun! :)

UPD

In Div. 1, scores for each problem will be 500-1500-1500-2000-2500.

In Div. 2, scores for each problem will be 500-1000-1500-2500-2500.

UPD

The contest is over. Thanks for participating.

Congrats the winners.

Division 1:

1. vepifanov
2. subscriber
3. RAVEman
4. ztxz16
5. anta

Division 2:

1. llllllllllll
2. geniucos
3. Misha100896
4. Temirulan
5. wwt15

You can find editorial here.

Hello everyone! Codeforces Round #254 is coming soon.

In this round, there will be a really cute boy named DZY. He loves many things, we can even say everything. He has a great passion for the gorgeous world, but he can't deal with everything he's interested in. So he needs your help, and he will present rating in return.

My thanks go to Gerald, who gave me much advice and helped about the problems. And I also would like to thank MikeMirzayanov, who created such a wonderful platform.

The problem setters are FancyCoder and me, and thank vfleaking, jqdai0815 and lsmll for testing.

Come and join us in helping DZY.

Good luck and have fun.

UPD

In Div. 1, scores for each problem will be 500-1000-2000-2000-2500.

In Div. 2, scores for each problem will be 500-1000-1500-2000-3000.

UPD

For technical reasons, the round will be delayed by 5 minutes.

UPD

The contest is over. Thanks for participating.

Congrats the winners.

Division 1:

1. subscriber

2. flydutchman

3. uwi

4. Egor

5. stevenkplus

Division 2:

1. lost3030

2. laekov_

3. JongMan

4. Daumilas

5. nnahas

You can find editorial here

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.

Hello!

We invite you to participate in Codeforces Round #253, which will take place on Thursday, June 19th at 19:30 MSK. The round will be held in both divisions.

It's my first Codeforces Round and I hope you will enjoy it!

Many thanks to Gerald for helping to prepare the round. Also I'd like to thank MikeMirzayanov for creating such a good platform. Also thanks to testers of this round: antonkov, Aksenov239, VArtem, subscriber, niyaznigmatul and to Delinur for translating statements.

Don't miss a chance to have fun of solving interesting problems!

UPD. Score distribution:

Div1: 500-1500-1500-2000-2500

Div2: 500-1000-1500-2500-2500

UPD2. The contest is over, thanks for participating!

Congtatulations to Div1 winners:

1) tourist

2) scott_wu

3) stevenkplus

3) gs12117

5) GlebsHP

And congratulations to Div2 winners:

1) tafit3

2) thnkndblv

3) MIT3

4) lucaslima

5) liuzhijian

My congratulations to tourist, only person who managed to solve all five problems, and only one who solved problem 442E - Gena and Second Distance!

You can find editorial here.

Today, on June 15 at 1 p.m. MSK the last round of Yandex.Algorithm elimination stage will begin. Crucial for determination of Yandex.Algorithm finalists 718 score points will be distributed during these 100 minutes. Three prize-winners of Yandex.Algorithm 2013 have already reserved a place in the final round. Have you?

Preparing a contest is not as popular a topic as the perennial question of "how to become red in three months", but still it stirs some interest in Codeforces community now and then. Earlier I've written about preparing Surprise Language Round and about emotional aspect of problemsetting; now it's time to share some facts about running regular contests.

Problems

How much time does it take to prepare, select, recall or find problem ideas?

How much experience solving competitive programming problems is necessary to be confident about inventing problems of your own?

Idea generation is a long-term, nearly continuous process. A couple of years ago when I was still an active problemsetter I used to create ideas from literally everything (a squirrel running... hey, this could be a great problem! — seriously, the problem is still there in my drafts, and a pretty complicated one) and to write them down. Then when I had time and inspiration to run a contest, I went through the drafts looking for ideas which would be 1) solvable and 2) nice and unusual enough, and combined them in a problem set.

The mystery of creating rounds unveiled by author of the 4 of them!
The guide for preparing the round without horror-fiction and pastorals!

Thanks for RodionGork, who push me to writing this post and thanks for hball1st, who push RodionGork to pushing me to writing this post.

Also, many thanks to RodionGork for the translation of this post to English.

1. Inventing problems

It's hard to advise anything on this point. There's no some standard way of creating problems — and if one have existed we'll have only "complicated algorithmic exercises" instead of "problems". People who participated in Russian Code Cup do know well the tasks of that sort.

To cook good and interesting problem there should be some idea! which came to your mind (and later to minds of participants of the contest). Even the simplest problems of A level for the Div2 should have some idea.

So here is the warning: creative way of thinking is trained from the childhood — and since so, not all people are equally good in inventing problems. Alas!

A coder can apply his breathtaking coding skills not only in different search engines but also in the mobile game industry. It is an option in Russia. If you do not believe — check this out: ZeptoLab company that created the world famous Cut the Rope game offers you the opportunity to see this for yourself. And yes, we are in Moscow.

It's not a secret that those who strive to achieve top coding skills — work hard, including work on his self-education. Here in ZeptoLab we aim to create the area that strongly encourages self-development. Specifically, we have recently purchased a company library with everything necessary to get new knowledge, an improvised reading room with sofas and armchairs.

We also conduct developer's contest inside the company so that our ZeptoCoders could solve non-trivial problems and impress each other with zeroes and ones. The winners get glory, valuable gifts and name-encrusted weapon (it's a joke, it’s not weapon)

We have recently opened our own algorithmic school here in ZebtoLab and the teacher is no other than the creator and the head of the whole wide Codeforces, Mike Mirzayanov! He is well-known among developers: Mike has trained a team that became the world champion in programming, so it's not hard to imagine the opportunities opened for ZeptoLab developers and the whole company. It's the first time that Mike teaches in such format, there are hardly any more examples of such corporate education systems in Russia and throughout the world.

Algorithms play an important role for us as the requirements for developers are quite tough: ideally, the application should output 60 frames per second on the target gadget. All game logic calculations should be very quick and preferably, with simple and not amortized complexity. Besides, we can afford a fine pre-processing to transport some calculations to the stage at which resources for the game are prepared. Understanding this facts, alongside with many more is the key to the quick gameplay. That is why we support the algorithmist's movement.

It's the first time when Zeptolab holds an algorithmic development contest based on Codeforces. Ingenious problems, fierce developer rivalry and cool prizes are waiting for you:

• 1st prize: Ipad Air, plush Om Nom, the championship T-shirt
• 2nd-3rd prize: Ipad Mini, plush Om Nom, the championship T-shirt
• 4-th-30-th prize: plush Om Nom, the championship T-shirt
• 31st-50th prize: the championship T-shirt

And just for some suspense, we add another prize:

We will randomly give the IPad Mini Retina to the person who makes it to the top 50 list of the contest champion. The IPad winner will be chosen like this: we sum up the times of all successful attempts of three top winners (in seconds starting from the start of the contest) and take a row with number s % 47 + 4, where s is the resulting sum. Being true coders. If the resulting line divides the place, then the priority goes to the earlier person to submit his last solved problem.

Besides, the person who shows good results in the contest will have the opportunity to apply for a job in our company by a simplified scheme. If you'd be interested to try working in the ZeptoLab team, tick the corresponding square at the registration.

You can find out more about what working with us is like at http://zeptoteam.ru/.

The championship will be conducted in a single round. The contest will go by the Codeforces rules. The round will be rated and both divisions can participate.

The date and time of the contest is: June 13, 2014, 15:30PM — 18PM (UTC).

The problem scores are: 1000-1000-1500-2500-2500-3000.

The contest is over! Thanks for all the participants! We hope you like the problems and the contest! Our special congratulations to the winners:

• The 1st place — KAN (Nikolay Kalinin, Russia, Nizhniy Novgorod) — iPad Air
• The 2nd place — winger (Vladislav Isenbaev, USA, Facebook) — iPad Mini
• The 3rd place — tourist (Gennady Korotkevich, Russia, Saint Peterburg, ITMO) — iPad Mini

All the participants on the places 1-30 will receive presents: plush Om Nom and the championship T-shirt. All the participants on the places 31-50 will receive championship T-shirt!

Additional prize will be received to the the 21st place winner: package.zaic (Vadim Zaycev, Russia, Novosibirsk, NSU).

Hello!

Soon (on June 8 at 19:30 MSK) you are lucky to participate in Codeforces Round for Div. 2 participants. Traditionally, Div. 1 participants can take part out of the competition.

Problems have been prepared by: Gridnev Vitaly (gridnevvvit) and Danil Sagunov (danilka.pro).

We want to thank Gerald for help in preparation of this round, Delinur for translation of statements and MikeMirzayanov for marvelous Codeforces and Polygon systems.

Scoring will be next 500 — 1000 — 1500 — 2000 — 2500.

Contest finished, congratulations to winners!

1. kuangbin10
2. ToumaKazusa
3. qiaoranpenxiang
4. rotoZOOM
5. umczca195

Editorials will be there

Good Luck!

Will begin today, at 21:00 MSK. All paricipants, advanced to the elimination stage, are welcome to participate through the link. This round will be 100 minutes long and will be scored using Grand-Prix 30 system. First place in Round 1 gave pperm86 100 score points and invitation to the final round in Berlin! Who will reserve his place among the finalists today?

Good luck!

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