Codeforces Round #290 Fox Ciel is back! I invite you to participate in Codeforces Round #290, which will start at the [standard time on next Monday](http://www.timeanddate.com/worldclock/fixedtime.html?day=2&month=2&year=2015&hour=19&min=30&sec=0&p1=166): This is my 4th round on Codeforces, my previous rounds: [#190](http://mirror.codeforces.com/blog/entry/8163), [#228](http://mirror.codeforces.com/blog/entry/10605), [#270](http://mirror.codeforces.com/blog/entry/13997). Last Div1 Round ([#286](http://mirror.codeforces.com/blog/entry/15842)) is so hard, so after notice that, we decide to reduce the difficulty of this round. (For example, current Div1-E was used as Div1-D) I hope more people can enjoy all tasks in this round: this time no task requires advanced knowledge like linear space or Fourier Transform. The background story will be Fox Ciel's life: learning programming, play games, traveling, have dinner and so on. Like Round [#228](http://mirror.codeforces.com/blog/entry/10605), top-20 contestants that are currently at...

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Codeforces Round #190 Hello, everyone! Do you want to train your skill by a contest before [ACM/ICPC Finals](http://icpc.baylor.edu/worldfinals)? Codeforces Round #190 will take place on [Friday, June 28th at 19:30 MSK](http://www.timeanddate.com/worldclock/fixedtime.html?msg=Codeforces+Round+%23190&iso=20130628T1930&p1=166&ah=2). This is the last chance to practice, don't miss it! I am [user:cgy4ever,2013-06-26] from China, and this is my first round on Codeforces, I hope you will love it. As usual, there will be 7 problems: 2 for Div2, 2 for Div1 and 3 for both. I am the writer of them. And I would like to thank [user:Gerald,2013-06-26] and [user:sdya,2013-06-26] for testing, and [user:MikeMirzayanov,2013-06-26] for the Codeforces project including [polygon](http://codecenter.sgu.ru/polygon/home) system. Good luck and have fun! **Update 1**: The score distribution for Both Division is regular (500-1000-1500-2000-2500). The main character of all problem will be: Fox Ciel. (See [here](http...

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Codeforces Round #270 Do you want to win a T-shirt? Do you want to learn how to design tasks for programming contest? Do you want to solve 7 tasks in 2.5 hours? So Codeforces Round #270 is right for you. It was designed by me in California, Assembled in polygon (so Thank you [user:MikeMirzayanov,2014-09-26] for the system and [user:Gerald,2014-09-26] for organize and testing), will start on [regular time this Sunday](http://www.timeanddate.com/worldclock/fixedtime.html?day=28&month=9&year=2014&hour=19&min=30&sec=0&p1=166), don't miss it! The organizers of **<a href="/blog/entry/13929">Marathon24</a>** decided to present gifts to the best finishers of the round! Best 25 participants will get Marathon24 tshirts! Thanks! <center> <img src="http://www.elmostshirts.com/images/tshirts.jpg"/> <br><small>It is just an image to attract your attention. Real tshirts will be designed specially for Marathon24!</small> </center> There are some articles introduced how to become a problem setter, like [Pro...

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Educational Codeforces Round 190 [Rated for Div. 2] <img alt="Neapolis University Pafos" src="/predownloaded/9a/33/9a332fadbb47050ba9405057df022a6e37eaf5c0.png" style="float:right;height: 200px; margin: 10px; max-width:40%;"/> Hello Codeforces! The series of Educational Rounds continues thanks to the support of the [Computer Science and Artificial Intelligence (CSAI)] (https://lp.jetbrains.com/academy/csai-program/) program at [Neapolis University Pafos](https://www.nup.ac.cy/), with scholarships provided by JetBrains. [contest:2230] will start on [contest_time:2230]. This round will be **rated for the participants with rating lower than 2100**. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest, you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally. **The problems in this round will partially intersect with Saratov SU internal contest (schedul...

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Codeforces Round #190 — Editorial **Update 1** Added links to my code. **Update 2** The links to my code seems not work, so I push my codes on github, and you find all of them here: [https://github.com/cgy4ever/cf190](https://github.com/cgy4ever/cf190) **Update 3** Fixed my solution of Div1-C (Div2-E). In this problem, we must find [centroid of tree](http://acm.sgu.ru/problem.php?contest=0&problem=134) instead of [center of tree](http://stackoverflow.com/questions/4020122/finding-center-of-the-tree). Thanks [user:RomaWhite,2013-07-03] for pointing this out and provide test case. And it seems that many solutions can pass the system test will fail on his test case (including my model solution). I feel apologetic for the weak test cases and wrong solution. **Update 4** Reformat the passage, I hope it would looks better. [problem:322A] Let's define remainNew = # of people haven't danced before. So at beginning remainNew = n+m, and we have: - During the 1st song, remainNew must decreased by at least 2. (B...

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Educational Codeforces Round 56 [Rated for Div. 2] Hello Codeforces! On [contest_time:1093] [contest:1093] will start. Series of Educational Rounds continue being held as [Harbour.Space University](https://harbour.space/) initiative! You can read the details about the cooperation between [Harbour.Space University](https://harbour.space/) and Codeforces in the <a href="http://mirror.codeforces.com/blog/entry/51208">blog post</a>. This round will be **rated for the participants with rating lower than 2100**. It will be held on extented ACM ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally. You will be given **7 problems** and **2 hours** to solve them. The problems were invented and prepared by Roman [user:Ajosteen,2018-12-14] Glazov, Adilbek [user:adedalic,2018-12-14] Dalabaev, Vladimir [user:Vovuh,2018-12-14] Petrov, Ivan...

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Educational Codeforces Round 99 [Rated for Div. 2] Hello Codeforces! On [contest_time:1455] [contest:1455] will start. Series of Educational Rounds continue being held as [Harbour.Space University](https://harbour.space/) initiative! You can read the details about the cooperation between [Harbour.Space University](https://harbour.space/) and Codeforces in the <a href="http://mirror.codeforces.com/blog/entry/51208">blog post</a>. This round will be **rated for the participants with rating lower than 2100**. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally. You will be given **6 or 7 problems** and **2 hours** to solve them. The problems were invented and prepared by Roman [user:Roms,2020-11-29] Glazov, Adilbek [user:adedalic,2020-11-29] Dalabaev, Vladimir [user:vovuh,2020-11-29] Petrov, Ivan [us...

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Educational Codeforces Round 69 [Rated for Div. 2] Hello Codeforces! On [contest_time:1197] [contest:1197] will start. Series of Educational Rounds continue being held as [Harbour.Space University](https://harbour.space/) initiative! You can read the details about the cooperation between [Harbour.Space University](https://harbour.space/) and Codeforces in the <a href="http://mirror.codeforces.com/blog/entry/51208">blog post</a>. This round will be **rated for the participants with rating lower than 2100**. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally. You will be given **6 problems** and **2 hours** to solve them. The problems were invented and prepared by Roman [user:Roms,2019-07-13] Glazov, Adilbek [user:adedalic,2019-07-13] Dalabaev, Vladimir [user:Vovuh,2019-07-13] Petrov, Ivan [user:Bl...

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Educational Codeforces Round 55 [Rated for Div. 2] On [contest_time:1082] [contest:1082] will start. Series of Educational Rounds continue being held as [Harbour.Space University](https://harbour.space/) initiative! You can read the details about the cooperation between [Harbour.Space University](https://harbour.space/) and Codeforces in the <a href="http://mirror.codeforces.com/blog/entry/51208">blog post</a>. This round will be **rated for the participants with rating lower than 2100**. It will be held on extented ACM ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally. You will be given **7 problems** and **2 hours** to solve them. The problems were invented and prepared by Mike [user:MikeMirzayanov,2018-11-27] Mirzayanov, Roman [user:Ajosteen,2018-11-27] Glazov, Adilbek [user:adedalic,2018-11-27] Dalabaev, Vladimir [user:V...

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Educational Codeforces Round 41 [Rated for Div. 2] Hello Codeforces! On [April 04, 17:05 MSK](https://www.timeanddate.com/worldclock/fixedtime.html?day=4&month=4&year=2018&hour=17&min=5&sec=0&p1=166) Educational Codeforces Round 41 will start. Series of Educational Rounds continue being held as [Harbour.Space University](https://harbour.space/) initiative! You can read the details about the cooperation between [Harbour.Space University](https://harbour.space/) and Codeforces in the <a href="http://mirror.codeforces.com/blog/entry/51208">blog post</a>. This round will be **rated for Div. 2**. It will be held on extented ACM ICPC rules. After the end of the contest you will have one day to hack any solution you want. You will have access to copy any solution and test it locally. You will be given **7 problems** and **2 hours** to solve them. The problems were prepared by Roman [user:Ajosteen,2018-04-03] Glazov, Adilbek [user:adedalic,2018-04-03] Dalabaev and me. We'd like to thank Mikhail [user:PikMike,2018-04-03] Piklaye...

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Codeforces Round #120 (Div.2) — editorial #### $A$ --- [Vasya and the Bus](http://mirror.codeforces.com/contest/190/problem/A) Firstly, if $n=0$, then children can't be in the bus, so if $m=0$ then the answer is $(0, 0)$, otherwise the answer is $"Impossible"$. Now $n>0$. If $m==0$, than it is only one possible variant of passage --- the answer is $(n, n)$. Otherwise, more grown-up take some children, less the sum that people pay. So, if only one adult takes all children, than we get maximal sum --- $n+m-1$. Maximum $min(n, m)$ adults can take the children with them, so the minimal answer is $n+m-min(n, m)=max(n, m)$. #### $B$ --- [Surrounded](http://mirror.codeforces.com/contest/190/problem/B) Let's find the minimum distance between two circles $L$. Then the answer to our problem is $L/2$. Now $d$ is the distance between the centers of the circles, $R$, $r$ --- their radiuses. There are 3 possible cases: - Circles don't intersect. Then $L = d - R - r$. Firstly, it's reachable: let's consider the segment, connecting the ce...

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COderfocers Codeforces | In English По-русски pathetique | Logout HOMETOPCATALOGCONTESTSGYMPROBLEMSETGROUPSRATINGEDUAPICALENDARHELP → Pay attention Before contest Codeforces Global Round 26 3 days Register now » *has extra registration → pathetique pathetique User''s contest rating in Codeforces communityRating: 1448 User''s contribution into Codeforces communityContribution: -77 Settings Blog Favourites Teams Submissions Problemsetting Groups Talks Contests → Top rated # User Rating 1 tourist 3757 2 jiangly 3647 3 Benq 3581 4 orzdevinwang 3570 5 Geothermal 3569 5 cnnfls_csy 3569 7 Radewoosh 3509 8 ecnerwala 3486 9 jqdai0815 3474 10 gyh20 3447 Countries | Cities | Organizations View all → → Top contributors # User Contrib. 1 maomao90 171 2 awoo 164 3 adamant 163 4 TheScrasse 159 5 maroonrk 155 6 nor 154 7 -is-this-fft- 152 8 Petr 147 9 orz 145 10 pajenegod 144 View all → → Favourite groups # Name 1 X-Camp 402H 2022 Fall View all → → Fi...

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Codeforces Global Rounds 2019: Current Results After Four Rounds In 2019, with the support of XTX Markets, 6 rounds of the new Codeforces Global Rounds will be held. These will be common rounds for both divisions of 7–9 problems each. The duration of the rounds will be 2-3 hours, depending on the number and complexity of the problems. All such rounds will be rated for all participants. <i>At each such round, 50 brand T-shirts will be handed out, and we will be happy to give T-shirts to all authors and problem testers.</i> The prizes for the 6-round series in 2019: - In each round top-100 participants get points according to the [table](https://pastebin.com/QT5sXEaT). - The final result for each participant is equal to the sum of points he gets in the four rounds he placed the highest. - The best 20 participants over all series get sweatshirts and place certificates. Current standings after four rounds: | Place | Contestant | = | Round 1 | Round 2| Round 3 | Round 4 | | - | - | - | - | - | - | - | | 1 | [user:tourist,2019-07-21] | 241...

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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://mirror.codeforces.com/blog/entry/49122) and [Who is the most popular?](http://mirror.codeforces.com/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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Educational Codeforces Round 190 (Rated for Div. 2) - C. Arrange the Numbers in a Circle # My Observation for C &mdash; Arrange the Numbers in a Circle Solved C in today's Div2 and wanted to share my observation/approach. Let: * `ones` = number of values equal to `1` * `others` = total count of all values greater than `1` * `cap` = maximum number of `1`s we can safely insert The key observation is: If a value appears `x` times (`x > 1`), then while keeping the condition valid, we can place at most [ \left\lfloor \frac{x-2}{2} \right\rfloor ] ones between its occurrences. Why? Because every triple of consecutive cards must contain at least two equal values. So between separating `1`s, we need at least two equal numbers together. For example: ```text 6 6 1 6 6 1 ``` works because every consecutive triple contains at least two `6`s. But: ```text 6 1 6 1 6 ``` does NOT work, since triples like: ```text 6 1 6 ``` break the condition. So each number contributes some "capacity" for accommodating ones. For every...

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February 27 -> March 18 : The Cost of Coding from IRAN Today I participated in Educational Codeforces Round 190 ( Rated for Div. 2 ) after a long break — my last contest was on February 27th. Why the gap ? Because on February 28th, the war started, and the internet in Iran was completely cut. and to reach CF, we have to buy expensive VPNs — over $2 per GB. I got connected a few days ago. Today, I finally gave my first contest after 3 months. Honestly, it feels strange, And a bit sad. So many lost opportunities, So many contests I missed, And the rating I could have gained .... Still , we try .

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Strange situation(three different results with different compilers) Hello, Codeforces. I've sent three submissions with different compilers on problem [problem:1553E] from last round and got different results(OK, ML 1, WA 1) [submission:123344376] [submission:123363613] [submission:123363479] Then i've ran valgrind (g++ 11.1.0) and discovered strange "still reachable" memory addresses, somehow connected with ios_base::sync_with_stdio. Then I realised, that fast IO was in solve function, which is called in main $T$ times for each test case. Then I moved it to main and got OK in all compilers. <spoiler summary="valgrind output on sample"> ~~~~~ ==36581== ==36581== HEAP SUMMARY: ==36581== in use at exit: 122,880 bytes in 6 blocks ==36581== total heap usage: 120 allocs, 114 frees, 197,964 bytes allocated ==36581== ==36581== 8,192 bytes in 1 blocks are still reachable in loss record 1 of 6 ==36581== at 0x484021F: operator new[](unsigned long) (vg_replace_malloc.c:579) ==36581== by 0x4982194: _M_allocate_internal_...

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Problem in CodeForce judge, giving wrong output for my solution this weird thing happened with me during a recent DIV 2 contest Codeforces Round #308 (Div. 2) . i submitted this code http://ideone.com/Jdt8it for problem http://mirror.codeforces.com/contest/552/problem/B and as u can see for input 99 i am getting the out 189 but here is my codeforces submission #11648222 and here it shows that for test case #4 which is actually input=99 my code is giving output 190. i tried running this same code on codechef IDE and there also with input 99 i got 189. so, can someone please help me why this weird thing might be happening!!!!

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Teams going to Gwalior/Pune Regionals **UPDATE:** I've uploaded the code that I used to generate this on Github, in case someone needs to generate something similar: [Codeforces Team Rating Calculator](https://github.com/abdullah768/Codeforces-Team-Rating-Calculator) The regional round has ended and here's the final Ranklist: https://www.codechef.com/public/rankings/ACM18GWR Inspired by the list of teams going to Kharagpur regionals, I decided to make one for Gwalior/Pune regionals. The list contains all the teams from the official Gwalior website. If you know the usernames of members of any of the teams. Please update the excel file: ### [HERE] (https://docs.google.com/spreadsheets/d/1jRvwzQzp1DOcazgI7jXBB8uY3u7Ze_eQ77Xa75_Q810/edit?usp=sharing) Team rating calculation has been done according to the official Codeforces team rating calculation formula. The table will be updated with details from the excel file every 6 hours or so. Last Updated: 10 pm, 12th December IST | No. | AIR | Team Name ...

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Hello Codeforces, ================= Although i did not participate in [Educational Codeforces round 190](https://mirror.codeforces.com/contest/2230/). I have tried to solve its first problem, https://mirror.codeforces.com/contest/2230/problem/A . The core of the problem says that: _There are $n$ students whom have access to keys of cost $a$ and $b$ , which are individual keys and group keys for an online course. For which, a group can be up to three. Our task is to minimize spending for all $n$ students, getting each one a key._ Now, if all $n$ kids need to have keys, then we can work by using the group keys for groups of 3 (max). Then as per the remainder, we can add along either $a$ or $b$ depending which is smaller. #### first part: check whether buying individually for 3 or group wise for 3 (max) is more optimal, spend it on $floor(n/3)$ kids (as we are buying in groups of 3 or 3 individually for max). mathematically : $min(3a, b)*floor(n/3)$ #### last part: after optimall...

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Problem Topics Good Day to you! I've been asked to make some topic-wise list of problems I've solved. Even though I couldn't involve all problems, I've tried to involve at least "few" problems at each topic I thought up (I'm sorry if I forgot about something "easy"). I've alredy made such list once anyway I've tried to include more problems now &mdash; so here it is: <spoiler summary="aho"> http://www.spoj.com/problems/ADAJOBS/ URI 2226 (5) //[NICE][NUMBERS][DP] http://www.spoj.com/problems/SUB_PROB/en/ http://mirror.codeforces.com/contest/696/problem/D 8 http://www.spoj.com/problems/AHOCUR/ 5 //Aho-Corassic + DP https://www.codechef.com/problems/LYRC (5) //Sample aho-brute-force http://mirror.codeforces.com/problemset/problem/346/B //Proposed by [user:bradyawn,2019-08-03] </spoiler> <spoiler summary="automat"> 6861 [LA] //CYK UVA 10679 //Suffix Automat http://www.spoj.com/problems/STRMATCH/ //Suffix Automat &mdash; trie might do too http://www.spoj.com/problems/NSUBST...

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