Codeforces Round #488 by NEAR **UPD:** обратите внимание, распределение баллов изменилось **UPD2:** [user:LHiC,2018-06-17] нашел ошибку в авторском решении на div1-F. Мы исследуем вопрос. **UPD3:** мы нашли правильное решение для div1-F и оба решения отправленных на контесте проходят все тесты против правильного решения => раунд по прежнему рейтинговый. Всем привет, Время старта Codeforces Round 488: [contest_time:993]. Это будет раунд для обоих дивизионов. Раунд будет длиться 2.5 часа (это на пол часа больше чем обычно). Контест подготовлен компанией [NEAR](http://near.ai/blog) и ее друзьями. В NEAR мы учим машины участвовать в соревнованиях по программированию. В [этом блог-посте](http://codeforces.me/blog/entry/59746) можно прочитать (на английском) о том, где сегодня находятся исследования в этой области, чем занимается непосредственно NEAR, и как вы можете помочь нам в этом нелегком деле. На контесте будет предложено по шесть задач в каждом дивизионе, 4 задачи из которых общие. Почти все ...

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Hack me! (Codeforces Round #278 (Div. 2)) Welcome in hacks' statistics in [contest:488]. That was really nice round for hackers! Many possibilities, many hacks, let's have a look! Post for Div. 1. contest <s>will be added later (there are pretty many hacks to parse :))</s> is [here](http://codeforces.me/blog/entry/14801). Previous posts can be found [here](http://codeforces.me/search?query=hackme). Your comments are always welcome. [cut] <h3>Stats</h3> Problem | <small>Successful hacks</small> | <small>Unsuccessful hacks</small> | Other* | Sum | <small>Solutions which can be hacked</small> | <small>Accepted solutions</small> | <small> All solutions on final tests</small>| :---:|:---:|:---:|:---:|:---:|:---:| <small> [problem:488A] </small> | 99 (46.05%) | 86 (40.00%)| 30 (13.95%) | 215 | 228 (12.20%) | 1641 (87.80%) | 1869 | <small> [problem:488B] </small> | 23 (50.00%) | 17 (36.96%)| 6 (13.04%) | 46 | 265 (63.55%) | 152 (36.45%) | 417 | <small> [problem:488C] </small> | 21 (65.62%) | 10 (31.25%)| 1 (3...

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Программа Пеликана и ACM MISIS «Спортивное программирование» в НИТУ «МИСиС»! Всем привет! В ВУЗах нашей страны стартовала приемная кампания. Компания Пеликан и центр ACM MISIS приглашают вас на новую программу **«Спортивное программирование» в НИТУ «МИСиС»**! Расскажем про направление в частности и про вуз в целом. **Пеликан** – образовательная компания, основанная Григорием Кондаковым (сооснователь ШАДа, в прошлом председатель экспертного совета Яндекса, инициатор создания и основной разработчик программы «Прикладная математика и информатика» ФИВТ МФТИ). Программа была запущена в 2009 году совместно с Виталием Гольдштейном (ex-Yandex, Google, серебряный медалист ICPC от СГУ, золото IOI) и Вадимом Никулин (ex-Yandex, ex-Facebook, финалист ICPC от ЯрГУ). За спортивное программирование в НИТУ «МИСиС» отвечает руководитель центра **ACM MISIS** Дарья Крохина (финалист ICPC от НИТУ «МИСиС», основатель проекта NlogN, руководитель сборов Volga Camp). В этом году мы набираем 100 студентов направления **«Информатика и вычислительная техника»** (50 — бюджетно...

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Помогите подобрать контр-тест к решению задачи на геометрию в вещественных числах Здравствуйте! Есть [задача](https://acmp.ru/index.asp?main=task&id_task=488) на acmp и [решение](https://ideone.com/dpRiL1) в вещественных числах с использованием типа **double**. Дан радиус окружности и даны прямые, заданные двумя точками, точки могут лежать как внутри круга, так и на окружности, требуется проверить для каждой пары прямых, лежит ли точка пересечения внутри круга, на нем или снаружи. Во входных данных все числа вещественные и могут быть заданы с 6-тью знаками после запятой, их абсолютные величины не превосходят $100$, то есть, нужно $8$ разрядов для точного представления. В ходе решения при пересечении прямых возникают числа, в которых $16$ разрядов, а также происходит их деление, в связи с этим есть ощущение, что точности типа **double** не хватает. Судя по всему, контр-тест должен содержать ровно две прямые, которые пересекаются очень близко к окружности, или пересекаются прямо на окружности. Я попробовал построить пересечение в точке $(99.999999, 0.014142)$ с...

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KEPPY Birthday Contest  On July 7, KEP.uz turns 4 years old! To celebrate this special day, we’re organizing a contest. I invite everyone to the [contest](https://kep.uz/competitions/contests/contest/441), which will take place on **July 7, 2025 at 14:35UTC**. Interesting problems await you in the contest. **Contest info:** - Number of problems: **9-10** - Difficulty of problems: **<= 2400** - Duration: **3 hours** - Contest type: **ACM20M** - Languages: **C++, Python, C, Kotlin, Haskell, R, Nodejs, PHP, C#, Java, Rust, Go** **Prizes:** **For International Participants:** - First place – **40$ (USDT)** - Second place – **20$** - Third place – **10$** **For Local Participants:** - First place – **300'000 UZS** - Second place – **200'000 UZS** - Third place – **150'000 UZS** - 4-5th places – **100'000 UZS** Link to the platform: https://kep.uz/competitions/contests/ P.S. Registrati...

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Hack me! — Year 2014 in review! (part 1.) 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 <s>(so far)</s>, the full list can be found [here](http://test.weaselcrow.com/pro/cf/hack2014/). <strong>Update: </strong> After last round, the ranking was updated. The last round was decisive: [user:mosiomohsen,2014-12-31] made 5 successful hacks and 1 unsuccessful and with 450 points, he managed to surpass [user:anta,2014-12-31]. Congratulations! [cut] <div></div> rank | handle | points | best rounds | accuracy | :---:|:---:|:---:|:---:| 1 | [user:mosiomohsen,2014-12-31] | 8...

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Codeforces Round #488 editorial [tutorial:994A] [tutorial:994B] [tutorial:994C] [tutorial:994D] [tutorial:994E] [tutorial:994F] [tutorial:993E] [tutorial:993F]

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Hack me! — Year 2014 in review! (part 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](/blog/entry/15326)). Now we will show all most accurate hackers. We will count the accuracy as the: $$\frac{\#successfulhacks}{\#allhacks}$$ Because there were a lot of flawless hackers, below we show only hackers with at least 10 successful hacks &mdash; still there were 36 of them! The full list of hackers' accuracy can be found [here](http://test.weaselcrow.com/pro/cf/ahack2014/). Also, below this table there is updated list of best hackers by summarized points, also the full list was updated [here](http://test.weaselcrow.com/pro/cf/hack2014/). [cut] <div></div> ### Accuracy rank | handle | accuracy | best rounds | points | :---:|:---:|:---:|:---:| 1 | [user:hetanglianyi,2014-12-25] | 100.0% | <small>[contest:462] [+19-0]</small> | 1900 (+19-0) | 2 | [user:bmerry,2014-12-25] | 100.0% | <small>[c...

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KEP Contest #18  I invite everyone to the [contest](https://kep.uz/competitions/contests/contest/488), which will take place on **December 21, 2025 at 15:00UTC**. Interesting problems await you in the contest. **Contest info:** - Number of problems: **9-10** - Difficulty of problems: **<= 2400** - Duration: **3 hours** - Contest type: **ACM10M** - Languages: **C++, Python, C, Kotlin, Haskell, R, Nodejs, PHP, C#, Java, Rust, Go** **Prizes:** - First place – **30$ (USDT)** - Second place – **20$** - Third place – **10$** Link to the platform: https://kep.uz P.S. Registration on the platform only via Gmail/Github.

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Weak Test case in [Codeforces Round #488 by NEAR (Div. 2)] Problem C So the problem state that " if one square is completely inside another, they intersect. If the two squares only share one common point, they are also considered to intersect. " Yet this [code](http://codeforces.me/contest/994/submission/39339704) gets AC and all it does try each pair of points and check if it intersect with the any other line in the second square so in total there are 4 lines of the sides and 2 for the diagonals. Yet you can have a square totally inside the other without any of the 6 lines intersect the second square as in this 0 0 100 0 100 100 0 100 1 53 3 51 5 53 3 55 The answer should be yes yet the AC code gets no. I'm not sure if there's a wrong case tho or just weak ones. <a href="https://imgur.com/4YQ9bxz"><img src="https://i.imgur.com/4YQ9bxz.jpg" title="source: imgur.com" /></a>

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Codeforces Popularity Ranking Hello Codeforces! There has been several blogs similar to this. I know about [TOP 15 most popular users on codeforces](http://codeforces.me/blog/entry/49122) and [Who is the most popular?](http://codeforces.me/blog/entry/21041). But as none of these are updated, I thought this might be helpful. I have just calculated the most popular handles in Codeforces. I only considered those handles which have at least one rated contest. Begging my pardon to them who hasn't participated in any rated round. And here, the popularity depends simply on the number of people you are friend of. The complete standings can be found [here](https://docs.google.com/spreadsheets/d/1ADlF-bd6pBYCap75yzf-pUnVwI9f9YmPkiYNW3lD-xo/edit?usp=sharing)(This may took a while to load at the bottom). Anyway here is Top 200 handles. | Rank | Handle | Follower | |---|---|---| 1. | [user:tourist,2018-08-22] | 14082 | 2. | [user:Petr,2018-08-22] | 6430 | 3. | [user:OO0OOO00O0OOO0O00OOO0OO,2018-08-22] | 420...

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Who participated most? **UPD:** The calculation updated, for some reason I filtered only CF style competitions. Now it includes everything. Still [user:ruban,2024-08-07] best :) I revisited some data from Codeforces and, [after 5 years](https://codeforces.me/blog/entry/72410), decided to calculate again who has participated in the most contests. I took into account all official contest participations, including those where a user participated unofficially. However, I excluded Practice/Virtual contests. P.S: I think no one will beat [user:ruban,2024-08-07] ever :) |Rank|Handle|Total|Official|Unofficial| |---|---|---|---|---| | 1 |  [user:ruban,2024-08-13] | 1164 | 1090 | 74 | | 2 |  [user:kmjp,2024-08-13] | 972 | 547 | 425 | | 3 |  [user:dreamoon_love_AA,2024-08-13] | 891 | 538 | 353 | | 4 | ![ ](https://codeforces.com/codeforces.org/s...

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Invitation to IPSC 2015  The next edition of [Internet Problem Solving Contest](http://ipsc.ksp.sk) is here! In case you don't know (yet), IPSC problems come in a great variety, from standard algorithmic ones to problems where you interact with the grader or need to find a specific input. Most problems have an easy input worth 1 point and hard input worth 2 points; otherwise, the scoring is ACM-like, with WAs on easy inputs giving time penalty 10 minutes instead of 20. The input files are available for download and you only upload your outputs (in a similar manner to GCJ, except there's no additional time limit). It's a team competition for teams of three. IPSC 2015 takes place on 20th of June, from [11:00 UTC](https://www.timeanddate.com/worldclock/fixedtime.html?month=6&day=20&year=2015&hour=11&min=0&sec=0) and lasts 5 hours. You may register [here](http://ipsc.ksp.sk/2015/register). #### CONTEST IS OVER. | Registered teams | |:----------------:| (...

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The entire cses problem set sorted by the number of solvers! I could not find it online so I made it myself, I hope you will find it useful! Problem : Number of solvers - Weird Algorithm : 73338 - Missing Number : 62177 - Repetitions : 54281 - Increasing Array : 50436 - Permutations : 44614 - Distinct Numbers : 33154 - Dice Combinations : 32886 - Number Spiral : 31522 - Bit Strings : 29957 - Minimizing Coins : 28281 - Trailing Zeros : 28124 - Coin Combinations I : 26104 - Two Sets : 25446 - Coin Piles : 24696 - Apartments : 24318 - Removing Digits : 24291 - Two Knights : 23643 - Grid Paths : 23168 - Ferris Wheel : 23109 - Counting Rooms : 22561 - Palindrome Reorder : 22339 - Coin Combinations II : 22133 - Sum of Two Values : 21004 - Maximum Subarray Sum : 20797 - Book Shop : 20376 - Creating Strings : 19359 - Building Roads : 19197 - Restaurant Customers : 18982 - Concert Tickets : 18507 - Apple Division : 18503 - Stick Lengths : 18339 - Movie Festival : 17839 - Message Route : 16337 - Building Teams : 1578...

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Milestones: ratings below 1500 and greatest rises (2024 edition) <i>Note.</i> This is an updated version of [this post](https://codeforces.me/blog/entry/104683). If you like [this style](https://codeforces.me/blog/entry/104320) more, please tell me in the comments. Since [user:tourist,2024-09-05]'s [breakthrough](https://codeforces.me/blog/entry/133401), I've received a lot of requests to update my old posts with rating achievements. However, I wasn't able to do it immediately since my method of doing it requires to download the rating change history of every user, which, in turn, requires to perform several hundred thousand requests to Codeforces, about which the website (and Cloudflare) is not happy. It took more that three days, but finally the job is done! Below are two tables. The first one is the greatest positive rating changes. The second one is the first users ever to reach some rating value. [cut] <table> <tr> <th>Place</th> <th>&Delta;</th> <th>Person</th> </tr> <tr> <td>1^st</td> <td><b>1182<...

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