UPDATE: the editorial is here

Link to the online mirror

Hello CodeForces! This year again, I'd like to invite you to the online mirror of an open championship of Switzerland called HC2 (the Helvetic Coding Contest). A mirror was also held one, two and three years ago.

The Helvetic Coding Contest is a yearly contest held at the EPFL in Lausanne by the PolyProg association. The contest itself took place on April the 13th, but the online mirror is scheduled on Sunday, 7th of July, 10:05 Moscow time. The duration is 4:30.

Rules:

• you can participate in teams or individually (1-3 people),

• standard ACM-ICPC rules (no hacking),

• the contest is not rated,

• if you have participated in the onsite contest, please do not participate in the mirror.

The contest this year is Doctor Who-themed. It features 5 series of 2-3 related tasks with increasing difficulty (easy/medium/hard). (For the online mirror, we will skip one series that had appeared in the onsite contest.) Sometimes it may be the case that a solution for the hard version solves all of them, but usually not. We think that the problemset is diverse and interesting, and while the contest is ACM-style, you will find that some problems are not so standard. Most easy&medium problems are even solvable in Python, so you can also recommend this contest to your newbie friends :) We promise to post a nice editorial as soon as the contest ends.

Acknowledgments: the problems were set by bgamlath, DamianS, esrever, milenkoviclazar, Wajeb (who coordinated), and myself. Thanks also go out to people who helped with the statements and testing: anayMehrotra, Michalina Pacholska (who also draws the cows), cdkrot for the Russian statements, KAN for CodeForces coordination, as well as everyone involved in the actual onsite contest, who are too many to name here. We also thank the sponsors Open Systems and nexthink. Lastly, thanks to MikeMirzayanov for CodeForces and Polygon (which was used to prepare the problems).

Finally, in a bit of autopromotion, note that you can use Hightail to automatically test your solutions :) Good luck!

After-contest UPDATE:

>>> Editorial <<<

Also:

• two extra problems from the onsite contest that were left out for the online mirror are available in the Gym

• the new uphacking feature is available for all problems except A3 and C3

Thanks to everyone who participated! We hope you have enjoyed the problems. The top three teams are:

1. 大象大象你的鼻子为什么那么长 (solved all 14 problems!): FizzyDavid, 300iq, TLE

2. zxtxdy (13 problems): cuizhuyefei, MarkF, zx2003

3. helveticow (12 problems): scott_wu, ksun48, ecnerwala

See you again next year!

UPDATE: the editorial is here

Hello CodeForces! This year again, I'd like to invite you to the online mirror of an open championship of Switzerland called HC2 (the Helvetic Coding Contest). A mirror was also held last year and two years ago.

The Helvetic Coding Contest is a yearly contest held at the EPFL in Lausanne by the PolyProg association. The contest itself took place on March the 17th, but the online mirror is scheduled on Saturday, 14th of April, 10:05 Moscow time. The duration is 4:30.

Rules:

• you can participate in teams or individually (1-3 people),

• standard ACM-ICPC rules (no hacking),

• the contest is not rated,

• if you have participated in the onsite contest, please do not participate in the mirror.

The contest this year is Star Wars-themed. It features 6 series of 2-3 related tasks with increasing difficulty (easy/medium/hard). Sometimes it may be the case that a solution for the hard version solves all of them, but usually not. We think that the problemset is diverse and interesting, and while the contest is ACM-style, you will find that some problems are not so standard. Most easy&medium problems are even solvable in Python, so you can also recommend this contest to your newbie friends :) We promise to post a nice editorial as soon as the contest ends.

Acknowledgments: the problems were set by maksay, boba5551, mukel, DamianS, esrever, and myself. Thanks also go out to people who helped with the statements and testing: bgamlath, Michalina Pacholska (who also draws the cows), and KAN for CodeForces coordination, as well as everyone involved in the actual onsite contest, who are too many to name here. We also thank the sponsors Open Systems and AdNovum. Lastly, thanks to MikeMirzayanov for CodeForces and Polygon (which was used to prepare the problems).

Finally, in a bit of autopromotion, note that you can use Hightail to automatically test your solutions :) Good luck!

After-contest UPDATE:

>>> Editorial <<<

Feel free to ask questions in this topic.

Thanks to everyone who participated! We hope you have enjoyed the problems despite the interruption in judging. The top 4 teams, who have solved all problems, are:

1. SpicyFriedTomatoes: AbstractKangaroo, jqdai0815

2. (｀・ω・´): King_George, ohweonfire, FizzyDavid

3. ymd队长ioi捧杯超稳: sunset, TLE, yanQval

4. ★SweeT DiscoverY★: dotorya, molamola., zigui

See you again next year!

Hello CodeForces! This year again, I'd like to invite you to the online mirror of an open championship of Switzerland called the Helvetic Coding Contest. A mirror was also held last year — see here: Helvetic Coding Contest 2016 online mirror (teams, unrated)

The Helvetic Coding Contest is a yearly contest held at the EPFL in Lausanne by the PolyProg association. The contest itself took place on April the 1st, but the online mirror is scheduled on Sunday, 28th of May, 11:05 Moscow time. The duration is 4:30.

Rules:

• you can participate in teams or individually (1-3 people),

• standard ACM-ICPC rules (no hacking),

• the contest is not rated,

• if you have participated in the onsite contest, please do not participate in the mirror.

You will help us find the cow Heidi and participate in some April-Fools-Day confusion. The contest will feature 5 series of 3 related tasks with increasing difficulty (easy/medium/hard). Sometimes it may be the case that a solution for the hard version solves all of them, but usually not. We think that the problemset is diverse and interesting, and while the contest is ACM-style, you will find that some problems are not so standard. Most easy&medium problems are even solvable in Python, so you can also recommend this contest to your newbie friends :)

Acknowledgments: the problems were set by Christian Kauth, boba5551, meret, DamianS and myself. Thanks also go out to people who helped with the statements and testing: maksay, Michalina Pacholska (who also draws the cows), Benjamin Schubert, Aleksa Stanković, Ruofan Zhou; Tatiana_S for Russian translations and KAN for CodeForces coordination, as well as everyone involved in the actual onsite contest, who are too many to name here. We also thank the sponsors Open Systems and AdNovum. Lastly, thanks to MikeMirzayanov for CodeForces and Polygon (which was used to prepare the problems).

Finally, in a bit of autopromotion, note that you can use Hightail to automatically test your solutions :) Good luck!

After-contest UPDATE:

>>> Editorial <<<

Feel free to ask questions in this topic.

Thanks to everyone who participated! We hope you have enjoyed the problems. Congratulations to the winners:

1. ★SweeT DiscoverY★: dotorya, zigui, molamola. (solved all problems!)

2. japan-cookie: sigma425, sugim48, yosupo (solved all problems!)

3. HSE Bluebell: Um_nik, Kronecker

4. Veteran: I_love_Hoang_Yen, chemthan, ngfam_kongu

5. m(_ _)m: tmt514, Shik, dreamoon_love_AA

6. never red: xxTastyHypeBeast666xx, gongy, rnsiehemt

7. rng_58

8. (｀・ω・´): FizzyDavid, ohweonfire

The winners of the onsite contest (Petr Team) also solved all problems.

See you again next year!

Hello CodeForces! I'd like to invite you to the online mirror of an open championship of Switzerland called the Helvetic Coding Contest.

The Helvetic Coding Contest is a yearly contest held at the EPFL in Lausanne by the PolyProg association. The contest itself took place in March, but the online mirror is scheduled on Sunday, 10th of July, 11:00 Moscow time. The duration is 4:30.

Rules:

• you can participate in teams or individually (1-3 people),

• standard ACM-ICPC rules (no hacking),

• the contest is not rated,

• if you have participated in the onsite contest, please do not participate in the mirror.

You will help the cow Heidi protect humanity against a zombie apocalypse. The contest will feature 6 series of 2-3 related tasks with increasing difficulty (say easy/medium/hard). Sometimes it may be the case that a solution for the hard version solves all of them, but usually not. In the onsite contest, teams could only access the medium version of a problem once they have solved the easy, and so on; in the mirror, there is no such constraint and you will be able to see all versions since the beginning. (Otherwise, the formats of the onsite and the mirror are the same.) We think that the problemset is diverse and interesting, and while the contest is ACM-style, you will find that some problems are far from standard :)

We promise to publish a very nice editorial as soon as the contest ends.

Acknowledgments: I had the pleasure of coordinating the team of problemsetters for this contest: gawry, Christian Kauth, maksay, boba5551, DamianS and myself. Thanks also go out to people who helped with the statements and testing: Jeremy Rabasco, Valerian Rousset, Sjlver, Wajeb; GlebsHP for Russian translations and CodeForces coordination, as well as everyone involved in the actual onsite contest, who are too many to name here. We also thank the sponsors Open Systems and AdNovum. Lastly, thanks to MikeMirzayanov for CodeForces and Polygon (which was used to prepare the problems).

Finally, in a bit of autopromotion, note that you can use Hightail to automatically test your solutions :) Good luck!

After-contest update:

• congratulations to the winners:

1. Zg: gustav, ikatanic

2. Endagorion

3. squark_tutan_RR: ngfam_kongu, I_love_Hoang_Yen, s-quark

4. mehlxneh: AntiForest, JoeyWheeler, xxTastyHypeBeast666xx

5. FTP++: pwypeanut, jacobtpl, zhangguangxuan99

6. Команда, в которой непростые в...ку с максимальным рейтингом: Um_nik, kb., Tinsane

7. Khodaro Shokr: SeyedParsa, PrinceOfPersia

8. Coder

• the editorial is available (PDF); feel free to ask questions here,

• hope you enjoyed the contest!

https://www.youtube.com/watch?v=cdDt1kpAUjU

See here:

• http://envisage-project.eu/proving-android-java-and-python-sorting-algorithm-is-broken-and-how-to-fix-it/
• https://github.com/abstools/java-timsort-bug

The bug is also present in CF's Java 7 (I didn't test Java 8 or Python). However, it seems that this cannot be used to hack Java or Python solutions, because the minimum size of a counterexample is 67108864 (67 million), too much to give in input. I guess that's a good thing -- imagine the mess this would create!

Hi! In this post I would like to introduce you to an application called Hightail.

Hightail is an automatic tester for programming contests such as CodeForces rounds. It will parse the problem statement, extract sample test cases (inputs and outputs) from it, and verify the correctness of your program against them. It is built to provide maximum automation and to relieve the contestant as much as possible.

A list of Hightail's features:

• parsing problem statements
• parsing entire contests (autoloading all problems)
• scheduling contest parsing ahead of time
• ability to comfortably view, edit and add test cases
• handling of all verdicts: WA, TLE, RE, even AC
• customizable time limits
• ability to create in/out files in your working directory
• detection of floating point values (comparing 0.1 vs. 0.10 does not give WA)
• easy-to-use UI, keyboard shortcuts
• resilient: it is multi-threaded so it will not let your program hang it; it will withstand large amounts of output from your program
• support for all contest languages (C++, Java, Python, ...)
• written in Java and should run on any OS

Some screenshots to give you an idea:

You will find more information on its homepage (scroll down to see the readme). And here's a direct link to downloads.

Hightail started out as a simple program that I wrote for myself quite some time ago, then it became a small open source project when some other people contributed code to it. I think that it is now sufficiently developed that it can be released to the public, i.e. announced publicly here, rather than being hidden somewhere on the net, possible to find only if you already know the name. (It's probably long overdue, actually.)

If you see bugs, have feature suggestions etc., please use GitHub to its fullest extent :) And look at the readme — it has a tutorial on how to contribute to Hightail.

I hope it will be useful to you :)

https://www.youtube.com/watch?v=jB2Ii86Oah0

https://www.youtube.com/watch?v=uNXdaBdwkEc

https://www.youtube.com/watch?v=3yG7ivRRQW4

https://www.youtube.com/watch?v=8PBgV3zLRaA

http://www.youtube.com/watch?v=HCk0UBfFoz8

http://www.youtube.com/watch?v=9YXESLQCOPs

https://www.youtube.com/watch?v=dguBHaokGEc

http://www.youtube.com/watch?v=1eaBfhFpLgo

Hi everyone,

I have a training problem and I think many of you have had it already, so I thought I'd ask. Our team from Wrocław qualified for the ICPC World Finals (yay!) and it would be good to practice on the past problems. Is there any way to do this as virtual participation in the past finals? Specifically, I'd like to have as many as possible of the following:

• online judge with the problems (UVa LiveArchive satisfies this)
• which is lenient on whitespace (it usually doesn't)
• ghost participants, live ranklist, seeing which problems have been solved up to this point etc.

I have found it hard to even find a precise ranklist (who solved which problem) for finals older than 2-3 years. There are no WF problemsets on acm.sgu.ru, nor here on CF Gym, and test data is only downloadable from ICPC website for 2011 up.

Am I too spoiled by the modern methods of preparation? :)

In the absence of a scheduled official CodeForces round, I'd like to invite you to train tomorrow (on SATURDAY — sorry, this mistakenly said Sunday earlier) with the Polish teams on the ICPC-training camp in Spała.

The contest is now visible on the CodeForces Gyms, where it will be conducted. Direct link: Spala training camp, Wroclaw contest

It's a 5-hour team contest (of course you may start individually). The starting time is 11AM Moscow Time (sorry for the late notice). You can also participate virtually afterwards.

Problems have been collected from various sources by our two teams from the University of Wrocław, Poland. They are not new/original but we believe it's unlikely for you to have had seen many of them before.

Be advised that the contest start time might get pushed back 5-10 minutes due to unforeseen onsite circumstances.

I'd also like to thank MikeMirzayanov for the excellent CodeForces and Polygon systems. Lest someone diss me in the first comment for not doing so ;)

Here is a screencast of me solving this round: youtube To watch comfortably (and see clear text), choose 1080p and watch full-screen on a 1920x1080 resolution or higher. Download link in 1680x1050: link

Here is a screencast of me solving this round: youtube To watch comfortably (and see clear text), choose 1080p and watch full-screen on a 1920x1080 resolution or higher. Download link in 1680x1050: link

Here is a screencast of me solving this round: youtube To watch comfortably (and see clear text), choose 1080p and watch full-screen on a 1920x1080 resolution or higher. Download link in 1680x1050: link

http://www.youtube.com/watch?v=TTCzdx3nwk0

See here.