Hello Codeforces,

as promised, tasks from the last year Polish Olympiad in Informatics are finally translated:

https://szkopul.edu.pl/p/default/problemset_eng/oi/25

Please ignore Polish titles, if you set the language to English (top right corner), you should see English statements.

I also want to recommend some problems, which (in my opinion) deserve some attention. I won't say why, because I don't want to spoil them, but if you have some spare time, please check out the following problems:

• Różnorodność
• Turniej trójinformatyczny
• Dwa długie lizaki

We are aware that the translations are not flawless, please let us know if we've made some mistakes.

Hey Codeforces!

I made a thing and I want to share it with the community.

We wanted to keep track of achievements and submissions in our team and using Codeforces status page is not really handy. Therefore, I introduce to you Team dashboard.

Here you can find some kind of a timeline for each member of your team, showing last submissions, contests and even blog posts on Codeforces.

Using this script is pretty easy, just specify up to 3 handles in the address, separated by semicolons (please check below). Also please keep in mind that this script was made in 3-4 hours, so there is almost certainly a handful of bugs. Also, the script asks a lot of queries to the Codeforces API, so sometimes not all requests are answered. You should wait a couple of seconds and try again.

Visit right now and bookmark your team:

http://weaselcrow.com/pro/cf/team/?h=Radewoosh;Errichto;kostka

You can also compare yourself with your archenemy:

http://weaselcrow.com/pro/cf/team/?h=kostka;olekluka

Upd: fixed some bugs, including incorrect places and no response if no one from the team submitted anything.

Upd2: fixed bug with blocked blogs.

Upd3: you can now request as many days as you want, adding d argument, for instance:

http://weaselcrow.com/pro/cf/team/?h=mnbvmar&d=60

Please use it carefully, as requesting too many days will probably timeout.

Upd4: added team rating, as calculated by Codeforces.

Upd5: added problem ratings.

Do you need even more Polish problems in your life? This year we are going to organize some contests on our educational platform (Szkopuł) and we decided to open them to the public. All contests will consist of problems from the previous editions of the POI, so you might be quite familiar with them if you ever solved problems on Szkopuł or on MAIN.

First contests (four of them) will imitate the first stage of the POI. Each contest will consist of three problems, last a week (start at 00:00 CEST on Monday, end at 23:59 CEST on Sunday) and have no feedback during the contest (but you have plenty of time to test your submissions). The first contest will start on September the 10th.

How to register? Just create an account on Szkopuł (https://szkopul.edu.pl/) and click on this invitational link: https://szkopul.edu.pl/c/tren18/join/RMQAKCjHhr1ceqVxywNIU5Kv/

Enjoy!

Shoutout to Benq, who in the really awkward interview at the IOI closing ceremony thank Codeforces for its contests!

CEOI 2018 is now a part of history!

Task statements, test data, model solutions, translations and some slides with solutions can be found at https://ceoi2018.pl/tasks/

We have two winners of CEOI 2018: Costin-Andrei geniucos Oncescu from Romania and Mariusz zdolna_kaczka Trela from Poland. Congratulations! Full scoreboard can be found at https://ceoi2018.pl/results/

The problems were added on Szkopuł and can be solved there (unfortunately, right now only in C/C++): https://szkopul.edu.pl/p/default/problemset_eng/ceoi/2018

We uploaded some photos to our Facebook fanpage: http://fb.com/ceoi2018

And finally, CEOI 2019 will take place in Bratislava, Slovakia!

The Central European Olympiad in Informatics (CEOI) is an annual informatics competition for secondary school students for central European countries. The 25th CEOI takes place in Warsaw, the capital of Poland.

This year, 13 countries will participate in the CEOI: Austria, Azerbaijan, Croatia, Czechia, Georgia, Germany, Hungary, Italy, Romania, Slovakia, Slovenia, Switzerland, and Poland. The full list of participants is available at: https://ceoi2018.pl/teams/

There will be two competition days: 8/14 and 8/16 (Tuesday and Thursday). We invite everyone to participate in the online mirror, hosted by the CS Academy (details). The contest will start both days one hour after the end of the onsite competition (at 13:00 UTC) and last 5 hours (till 18:00 UTC).

Further info can be found on the official website of the competition: https://ceoi2018.pl/ and our Facebook fanpage: https://facebook.com/ceoi2018/.

You asked for it and we are trying to deliver! Almost all tasks from the 22nd, 23rd and 24th Polish Olympiad in Informatics are already translated and are available on Szkopuł:

• https://szkopul.edu.pl/p/default/problemset_eng/oi/22
• https://szkopul.edu.pl/p/default/problemset_eng/oi/23
• https://szkopul.edu.pl/p/default/problemset_eng/oi/24

Tasks from the last edition (25th) are being translated.

Please don't be scared of Polish titles, that's because we are trying to unify all problems. The problem statements should be in English. In particular, check if your language is set to English (the flag in the upper-right corner).

Out of all 396 original tasks from all 25 editions of the Polish Olympiad in Informatics, over 83% are available in English right now. I really hope that we can reach 100% later this year to celebrate the 25th birthday of the POI, but I don't want to promise anything.

Enjoy!

The famous book with tasks from the polish programming contests can be ordered again. This time the book was printed in a more reasonable amount :)

https://ksiegarnia.pwn.pl/Looking-for-a-challenge-The-ultimate-problem-set-from-the-University-of-Warsaw-programming-competitions,748491781,p.html

Enjoy!

Update: I just noticed that books cannot be delivered outside Poland. We will do something about this. :P

Update 2: Check out this blog: http://codeforces.me/blog/entry/59876

Hey everyone,

I know that nearly everyone is looking towards China right now, but let's try (like in a previous year) to create a list of IOI 2018 participants.

The list can be found here: http://weaselcrow.com/pro/cf/ioi/18/

How to add or update data? Please fill the following form: https://goo.gl/forms/he4DlrzfKWw35lx73

Just in a month from today, IOI in Iran will start.

Below you can find the complete list of participants (based on registration and data provided by Codeforces community): http://weaselcrow.com/pro/cf/ioi2017/

Some random facts:

• 326 students from 84 countries will participate (this will be a new record, the previous record was at IOI 2015 in Kazakhstan — 322 contestants from 83 countries)
• El Salvador, Iceland, Morocco, and Palestine will send their contestants for the very first time, welcome to IOI!
• 114 (almost 35%) participants were already in Russia, including golden medalists: Reyna, yutaka1999, pacu, natsukagami, also Cyprus and Bangladesh will have exactly same team, as in previous year.

Maintaining tradition from last year and the year before last I want to start a list of participants of the International Olympiad in Informatics 2017.

This year IOI will be held in Tehran, Iran between 28th July and 4th August.

Official website: http://ioi2017.org/

Facebook page: ioi2017.org

Update:

Check out the new version of this list with sorting and CF rating (updated by CF API):

http://weaselcrow.com/pro/cf/ioi2017/

Feel free to add (confirmed!) participants from your country here: https://goo.gl/forms/4BskHKHmZ70Tdck22 (preferred way) or below, in comments.

This topic is probably as old as programming itself, but maybe someone can help me.

I had an opportunity to organize several camps for some pupils (age 14-16). They were pretty good in mathematics and puzzles in general. My job there was to show them why programming (and algorithms) is also pretty decent.

I show them some problems, teach them basic programming skills, but after several years I noticed that the most important thing in teaching such things is showing them why programming is important and why should they learn this. I should sell them not knowledge, but attitude during this week.

Do you have any idea how to convince younger generations why they should start programming? Why did you start? What is convincing you to still solve algorithmic problems?

Happy New Year and thanks in advance for your responses and ideas :)

In next week, Baltic Olympiad in Informatics 2016 will be held in Helsinki, Finland.

The Baltic Olympiad in Informatics (BOI) is a programming contest for secondary school students. It started in 1995 with only 3 participating countries and grew substantially over the years. Now BOI encompasses about 60 participants from 9 countries situated around the Baltic Sea. Each country is invited to send up to 6 participants to the Olympiad, and the host country usually sends two teams. (from BOI 2015 webpage).

The contest website: https://www.cs.helsinki.fi/group/boi2016 and facebook page: https://web.facebook.com/boi2016/

Even Codeforces Round #352 is taken into account in schedule!

Did you notice that in the top navbar something is missing?

Old navbar:

Current navbar:

I wonder if I miss something about these links being deleted, but I hope they will come back (many questions like this can be answered directly by reading HELP page, am I right?). Moreover: these pages still work.

TLDR: Please give back help and testlib to navbar!

Welcome back to Hack me! blog!

You asked for it, and you have it. After over one year I am back with short description of the best hackers and the most common hacks in Codeforces Round. The formula is quite new and poorer than before, I should say. I left only the most important messages.

If you are not familliar with the series, you may check my first post about it or all posts.

Hey there, I couldn't sleep, so I spend almost an hour to play with some Python and answering some questions about "who was... in 2015 on Codeforces" (also checking if I still remember anything :)). So — have you ever wondered who was the best in this year on Codeforces? I will try to answer to your (and mostly mine) questions. Here is the first part (and maybe the last :)) of this year review.

Hey there.

There is a contest in Poland called Deadline24. It is 24 hours long programming marathon where you are programming bots for games.

We are looking (with Skedar) for a third party member. We can offer:

• noble company
• almost certainty to advance to the finals (we are in the finals since we started participating) and the finals includes:
• trip to Silesia in Poland, to the old carbon mine, (unfortunately you will have to pay for your travel yourself),
• possibility to die from overeating (the organizers provide food for 24 hours: pizzas, snacks, etc.),
• flashdisk (lol :))
• really nice diploma and cerificate (in English, of course)

The tasks are in English.

Scheldule:

• Registration: up until February 26, 2015
• Qualifying round: March 1, 2015
• Finals (on site!): April 7-8, 2015

What we want is someone who can write a program (not necessarly fast and good program, but it will be nice :)). If you took part in such contests, that will be really big point. Please write a message to me if you are interested and tell us something about yourself. I will try to answer to all your questions.

Maybe you have a team and you want to participate? Check their website (link above).

Hey there.

I haven't posted any post in this year and some people asked what will happen with my posts about hacks. The answer is "they will come" in indefinite time. I am unfortunately quite busy with other stuff (I didn't even had enough time to take part in any round this year :(). The statistics are ready, but I don't have enough time to look at hacks and describe them. For those, who are waiting, I am really sorry.

I also want to upgrade my scripts — I took all of your suggestions and I am currently thinking how to fulfil all your whims :) For example, I want to keep such ranking as was seen here and update it after every round.

Looking forward to more of your feedback and see you later :)

Still in buoyant humour after Good Bye 2014? While waiting for the editorial, maybe you would like to know why there were so many hacks in the last round of this year?

As always, please share you thoughts, ideas or maybe hacks :)

Previous posts can be found here.

Hey there!

This is the third part of my little summing-up of the ending year. This one is pretty big. I went through all submissions from every contest from this year and created the list of the most hacked problems in this year. Moreover, this list has some other informations like what was the problem with the biggest or the lowest number of accepts to it, what problems had strong and weak pretests and many more...

Check the full list here.

Be careful with some data, because you may not remember the Black Day of Codeforces, when some data was lost and in fact, it appears that there were no participants (and submits) for some round (it apply to most of the contests in February). Also, you may surprised that some hacks are count several times — it is because some people resubmitted their hacked solutions (without success) and I wondered where put such submission. I decided to keep it there (frankly, there were not so many such submissions so it doesn't change a lot).

The previous parts:

• best hackers by sum of points,
• most accurate hackers.

And statistics from Codeforces Round 284 (Div. 2) (this round should be named after dreamoon_love_AA).

Previous posts can be found here, including post for div. 1.

Let's take a look at Christmas Round (Codeforces Round 284 (Div. 1)).

Because of not-so-good scheduling, I didn't take part in it (neither any of my friends did). In Poland, it is a nice time to spend time with family, not like this. If you are interested how Christmas look like in Poland, check out polishchristmasguide.com.

Ok, enough complaining, let's look at the hacks.

Previous posts can be found here, including post for div. 2.

Merry Christmas everyone!

One round behind us, one more to go in this year. It's time for the second part of my little summing-up (last post can be found here). Now we will show all most accurate hackers. We will count the accuracy as the:

Because there were a lot of flawless hackers, below we show only hackers with at least 10 successful hacks — still there were 36 of them!

The full list of hackers' accuracy can be found here.

Also, below this table there is updated list of best hackers by summarized points, also the full list was updated here.

Hey there! Since new year is coming, I want to start little summing-up of the ending one (of course we still talk about hacks :)).

I wrote another short script, which purpose was to summarize all hacks in the 2014. I wanted to upload it after two last rounds, but mostly because of little differences (especially between first and second place), I did it before last rounds. Maybe the next rounds will be more exciting because of it.

Below there is a list of 50 best hackers in this year (so far), the full list can be found here.

Update: After last round, the ranking was updated.

The last round was decisive: mosiomohsen made 5 successful hacks and 1 unsuccessful and with 450 points, he managed to surpass anta. Congratulations!

And Codeforces Round 283 (Div. 1).

It wasn't very good round for hackers (especially because of strong pretests), but still — let's take a quick look. (Hacks description will be added later, maybe tomorrow?)

Previous posts can be found here, including div. 2.