Codeforces Round #652 (Div. 2) $$~-\text{In the name of God}~-$$ Hi community, I'm glad to invite you to my first contest, [contest:1369] which will be held at [contest_time:1369] ($\text{notice the unusual time}$). The problems are mainly prepared and invented by me. The round is rated for participants with rating strictly less than $2100$, others are able to take part in the round out of competition. You will be given $2$ $\text{hours}$ to solve $6$ $\text{problems}$. Firstly I'd like to thank [user:adedalic,2020-06-15] for coordinating and reviewing the round, as well as helping with many different things. I'd like to thank [user:antontrygubO_o,2020-06-21], [user:physics0523,2020-06-21], [user:McDic,2020-06-21], [user:Ashishgup,2020-06-21], [user:dannyboy20031204,2020-06-21], [user:Kuzey,2020-06-21], [user:Return_0,2020-06-21], [user:FieryPhoenix,2020-06-21], [user:ma_da_fa_ka,2020-06-21], [user:ITDOI,2020-06-21], [user:AM_I_Learning,2020-06-21], [user:pikmike,2020-06-21], [user:lynmisakura,2020-06-...

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Codeforces Round #652 (Div. 2) Editorial ####[A. FashionabLee :](https://codeforces.me/contest/1369/problem/A) Invented by [user:DeadlyCritic,2020-06-16]. <spoiler summary="Brief Solution"> $\mathcal Brief\;\mathcal Solution :$ A $n$-regular convex polygon is beautiful if and only if $n \% 4 = 0$. ($\%$ is the modular arithmetic symbol) </spoiler> <spoiler summary="Complete Proof"> [tutorial:1369A] </spoiler> <spoiler summary="Python solution"> ~~~~~ t = int(input()) for testcase in range(t): n = int(input()) if(n%4 == 0) : print("Yes") else : print("No") ~~~~~ </spoiler> <spoiler summary="C++ solution"> ~~~~~ #include <iostream> using namespace std; int main(){ int t; cin >> t; while(t--){ int n; cin >> n; if(n % 4 == 0){ cout << "YES\n"; } else cout << "NO\n"; } } ~~~~~ </spoiler> ####[B. AccurateLee :](https://codeforces.me/contest/1369/problem/B) Invente...

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Codeforces Round #377 Problem analysis (Unofficial) Since the official editorial is yet to be released and people are starting to ask for editorial, I decide to write this problem analysis and hopefully this may help the situation. =] Sorry for my bad English if I made some grammatical mistakes. [732A. Buying a shovel](http://codeforces.me/problemset/problem/732/A) --------------------- We could simulate the buying process &mdash; just buy until you can buy without change. As the problem statement have already stated, you can always buy 10 shovels without change, so there is at most 10 iterations. [C++ solution](http://codeforces.me/contest/732/submission/21587769) [732B. Cormen — The Best Friend Of a Man](http://codeforces.me/contest/732/problem/C) --------------------------------------- Iterate the days from left to right, and increase the days greedily on the right to fulfill the requirement. Take a look at this figure if you don't understand why this doesn't know why this works. ![ 732 example ](http...

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Contests hack statistics (Number of hacks by round) Just felt like gathering some data about hacks. Parsed around ~400 last contests Probably it would be worth it to also include SFT, but whatever Educational 96 is not finished yet but also whatever Last 100 ------------------ **847** Educational Codeforces Round 96 (Rated for Div. 2) **30** Codeforces Global Round 11 **248** Codeforces Round #674 (Div. 3) **0** 2020 ICPC, COMPFEST 12, Indonesia Multi-Provincial Contest (Unrated, Online Mirror, ICPC Rules, Teams Preferred) **97** Bubble Cup 13 &mdash; Finals [Online Mirror, unrated, Div. 2] **86** Bubble Cup 13 &mdash; Finals [Online Mirror, unrated, Div. 1] **20** Codeforces Round #675 (Div. 2) **1** Codeforces Round #672 (Div. 2) **70** Codeforces Round #671 (Div. 2) **58** Educational Codeforces Round 95 (Rated for Div. 2) **3** Codeforces Round #673 (Div. 2) **11** Codeforces Round #673 (Div. 1) **73** Codeforces Round #667 (Div. 3) **121** Grakn Forces 2020 **4** Co...

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Practice Educational Round Problems by tags Problems in educational rounds are generally straightforward and I've found them helpful for practising a new concept. I wrote a little python script for myself which uses the CodeForces API to fetch problems across all educational rounds, sorted by the difficulty in chosen tags. (There's no way as far as I can see to do this on the platform itself) I'm sharing it here in case someone finds it helpful: https://github.com/yashrajkakkad/cf-educational. Sample output when tags='dsu': 1400 News Distribution https://www.codeforces.com/problemset/problem/1167/C 1700 Swaps in Permutation https://www.codeforces.com/problemset/problem/691/D 2000 Imbalanced Array https://www.codeforces.com/problemset/problem/817/D 2000 SUM and REPLACE https://www.codeforces.com/problemset/problem/920/F 2100 Connected Components? https://www.codeforces.com/problemset/problem/920/E 2100 Minimum spanning tree for each edge https://www.codeforces.com/p...

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Discussions Of CodeForces Round <h2 style="text-align: center;"><u>CodeForces Round</u></h2><div><u><br></u></div><div><a href="http://codeforces.me/blog/entry/84">CodeForces Beta Round 1</a><br></div><div><br></div><div><a href="http://codeforces.me/blog/entry/97">CodeForces Beta Round 2</a></div><div><br></div><div><a href="http://codeforces.me/blog/entry/141">CodeForces Beta Round 3</a></div><div><br></div><div><a href="http://codeforces.me/blog/entry/158">CodeForces Beta Round 4</a></div><div><br></div><div><a href="http://codeforces.me/blog/entry/196">CodeForces Beta Round 5</a></div><div><br></div><div><a href="http://codeforces.me/blog/entry/220">CodeForces Beta Round 6</a></div><div><br></div><div><a href="http://codeforces.me/blog/entry/239">CodeForces Beta Round 7</a></div><div><br></div><div><a href="http://codeforces.me/blog/entry/258">CodeForces Beta Round 8</a></div><div><br></div><div><a href="http://codeforces.me/blog/entry/276">CodeForces Beta Round 9</a></div><div><br></div><div><a href="ht...

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Educationals Rounds Link (From Starting) I saw on Codeforces on a regular basis, that there are a lot of questions and answers about practicing and practicing more. Although It is my opinion that the Educationals Rounds are best for this, at least for people like me. They learn from it and the problems are very nice and interesting. There are many Educationals Rounds will come and I will also try my best to keep this blog update. Although if you want to generate these links <s>at any time</s> locally you can find the code on my GitHub repo: https://github.com/adshin21/Codeforces-Contest-Selector-By-Div-s So I've collected the links for all the educationals rounds that has happened. <table class = "bordertable" align="center"> <tbody> <tr> <td>Educational Round 1 </td> <td> <a href= " http://codeforces.me/contest/598" >http://codeforces.me/contest/598</a></td> <tr> <tr> <td>Educational Round 2 </td> <td> <a href= " http://codeforces.me/contest/600" >http://codeforces.me/contest/600</a></td> <tr> <tr> ...

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Tracking Codeforces Educational Rounds - Educational Codeforces Round 1 (http://codeforces.me/contest/598) - Educational Codeforces Round 2 (http://codeforces.me/contest/600) - Educational Codeforces Round 3 (http://codeforces.me/contest/609) - Educational Codeforces Round 4 (http://codeforces.me/contest/612) - Educational Codeforces Round 5 (http://codeforces.me/contest/616) - Educational Codeforces Round 6 (http://codeforces.me/contest/620) - Educational Codeforces Round 7 (http://codeforces.me/contest/622) - Educational Codeforces Round 8 (http://codeforces.me/contest/628) - Educational Codeforces Round 9 (http://codeforces.me/contest/632) - Educational Codeforces Round 10 (http://codeforces.me/contest/652) - Educational Codeforces Round 11 (http://codeforces.me/contest/660) - Educational Codeforces Round 12 (http://codeforces.me/contest/665) - Educational Codeforces Round 13 (https://codeforces.me/contest/678) - Educational Codeforces Round 14 (https://codeforces.me/contest/691) - Educational...

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Cheaters found in CF Round #660 , #658 and #657 I found these two cheaters in Yesterday's contest ([ Codeforces Round #660 (Div. 2) ](https://codeforces.me/contest/1388)). They are from from the **same institute** (Jaypee Institute of Information Technology, Noida). They have been doing this in all almost **every past contests** they both participated. CF authorities should atleast **disqualify them from Round #657** , as they have gained positive deltas from that round unlike other rounds where they have dropped. User 1: _**Agraj Garg**_ [agrajgarg](https://codeforces.me/profile/agrajgarg) User 2: _**Vatsal Agarwal**_ [Warhead38](https://codeforces.me/profile/Warhead38) Submissions(For CF Round #660): A: [88462008](http://codeforces.me/contest/1388/submission/88462008) by Agraj and [88463088](http://codeforces.me/contest/1388/submission/88463088) by Vatsal (Apparently Vatsal has also submitted two absurd solutions to fool the authorities ) B: [88479313](http://codeforces.me/conte...

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mass cheating by some people of same organisation Hello everyone, I have been told by my friend that many students from their institute are involved in cheating on many contests of Codeforces and CodeChef and many of them have been plagiarised on Codechef. So I check codes of top-ranking students from the last contest i.e. Codeforces Round #652 (Div 2) and found that 3 of them have same code with a different basic template and different variable names and in some cases, they had unnecessary loops in their codes (which are of no use), I think they had done so that they can't be caught. Please [user:MikeMirzayanov,2020-06-24] takes some strict actions against them. here's the link of first-person code &mdash; https://codeforces.me/contest/1369/submission/84770782 here's the link of second person code &mdash; https://codeforces.me/contest/1369/submission/84775423 here's the link of third-person code &mdash; https://codeforces.me/contest/1369/submission/84779461 This is not just the single case, you can found that these 3 per...

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All DIV 3 contests links for practice Hello friends I am sharing the link of all div 3 links for practice. -------------------------------------------------------------------- <br><br> Div3 1: https://codeforces.me/contest/977<br> Div3 2: https://codeforces.me/contest/978<br> Div3 3: https://codeforces.me/contest/988<br> Div3 4: https://codeforces.me/contest/999<br> Div3 5: https://codeforces.me/contest/1003<br> Div3 6: https://codeforces.me/contest/1005<br> Div3 7: https://codeforces.me/contest/1006<br> Div3 8: https://codeforces.me/contest/1015<br> Div3 9: https://codeforces.me/contest/1029<br> Div3 10: https://codeforces.me/contest/1066<br> Div3 11: https://codeforces.me/contest/1077<br> Div3 12: https://codeforces.me/contest/1092<br> Div3 13: https://codeforces.me/contest/1095<br> Div3 14: https://codeforces.me/contest/1102<br> Div3 15: https://codeforces.me/contest/1108<br> Div3 16: https://codeforces.me/contest/1118<br> Div3 17: https://codeforces.me/contest/113...

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Me and DeepSeek spent a weekend analyzing 8000 CF problems. Here's what we found # Me and DeepSeek analyzed 1600 Codeforces contests and 8000+ problems — some interesting patterns please check this result : https://ayushgirigoswami.github.io/codeforces_analysis_report/ A few weeks ago I got curious about something most of us probably notice intuitively but rarely measure properly: * Is Codeforces getting harder over time? * Which topics are becoming more common? * Are some problems overrated or underrated? * How different are Educational rounds from regular rounds? So I wrote a Python script that pulls contest/problem data from the CF API, analyzes ratings + tags, and generates interactive visualizations. ### Report https://ayushgirigoswami.github.io/codeforces_analysis_report/ ### Source code https://github.com/Ayushgirigoswami --- ## Dataset The analysis includes: * 1600 contests * 8354 rated problems * Div.1 / Div.2 / Div.3 / Div.4 / Div.1+2 * 2011 → present Average problem rating across the dataset: **1793** --- ...

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Topcoder Single Round Match 652 Всем привет! Завтра, в [18:00 MSK](http://www.timeanddate.com/worldclock/fixedtime.html?&day=09&month=03&year=2015&hour=11&min=00&sec=0&p1=179) состоится [SRM 652](http://community.topcoder.com/tc?module=MatchDetails&rd=16316). Предлагаю обсудить задачи после контеста!

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Topics Problems Good Day to you! While a lot of us, when he begins to start competitive programming he found difficult to found problems on some topics in the beginning to practice of it, and same thing for a lot of ICPC Communites that they have started. These are some topic not advanced and videos, problems and articles on them. <br> <spoiler summary="Prefix Sum & Frequency Array"> [Wonderful Coloring](https://codeforces.me/contest/1551/problem/B1) [Do Not Be Distracted](https://codeforces.me/contest/1520/problem/A) [Letter](https://codeforces.me/problemset/problem/43/B) [Pangram](https://codeforces.me/problemset/problem/520/A) [Andryusha and Socks](https://codeforces.me/contest/782/problem/A) [Count Numbers](https://codeforces.me/group/c3FDl9EUi9/contest/262795/problem/A) [Count Characters](https://codeforces.me/group/c3FDl9EUi9/contest/262795/problem/B) [Range Sum Query](https://codeforces.me/group/c3FDl9EUi9/contest/262795/problem/E) [Count a's](https...

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Blog collection <p>________________________________________________________________________________________<br><br></p><h3><b>Puzzle</b></h3><ul><li><a href="http://codeforces.me/blog/entry/66">Red and Black hair</a>, </li><li><a href="http://codeforces.me/blog/entry/112">The 12 chairs and diamonds</a></li><li><a href="http://codeforces.me/blog/entry/228">Monty Hall Problem</a></li></ul><br><br><h3>Useful <br></h3><ul><li><a href="http://codeforces.me/blog/entry/70">Petr Mitrichev, 3 days in Sao Paulo Training Camp 2010</a></li><li><a href="http://codeforces.me/blog/entry/512">Useful links</a></li><li><a href="http://codeforces.me/blog/entry/529">Problem Set Analysis Of CodeForces</a></li><li><a href="http://codeforces.me/blog/entry/546">Discussions Of CodeForces Round</a></li><li><a href="http://codeforces.me/blog/entry/1492">ALL CodeForces rounds Tutorial</a></li><li><a href="http://codeforces.me/blog/entry/1534">Online Judge Locator</a></li><li><a href="http://codeforces.me/blog/entry/170...

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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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Concern about my rating Hello, I have a concern about the rating. In my last contest (Round #657, only Div 2), I got about 1200th rank out of about 8600 contestants. That's roughly top 15%. This boosted my rating by +11 points. I am guessing that indicates the performance of a 1900 rated contestant. However, the contest before (Round #652, only Div 2), I got ranked again 1200th, but this time about 14500 contestants participated. That put me on top 10 percent. However, that time I actually lost -4 points, which this time is about the performance of a 1840 one. My question is, even though I did quite better on my 2nd previous contest, which did I get 15 points less? Is it because of rating inflation? Or maybe because the last contest was an outlier (much less participation than the COVID era amount of users)?

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Topcoder Single Round Match 652 Hello everyone!<br><br> [Topcoder SRM 652](http://community.topcoder.com/tc?module=MatchDetails&rd=16316) will be held tomorrow at [20:30 IST](http://www.timeanddate.com/worldclock/fixedtime.html?&day=09&month=03&year=2015&hour=11&min=00&sec=0&p1=179), **1 hour earlier than usual** time!<br><br> Let's discuss problems after contest!<br>

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Round 652 (Div 2) #1369C- RationalLEE I have used the following approach but it is getting me a WA. Please help me out if you can. - Sorting the elements in descending order while the friends in ascending order. - distributing elements (highest to lowest) one by one among friends. ex: E: 7 7 6 6 3 2 1| F: 1 1 2 3 distribution: (7) &mdash; &mdash; -| (7) (7) &mdash; -| (7) (7) (6) -| (7) (7) (6) (6)| (7) (7) (6,3) (6)| (7) (7) (6,3) (6,2)| (7) (7) (6,3) (6,2,1)| Under which testcase will this give a wrong solution

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Run Time Error on Codeforces Round #652 (Div 2) Problem C Can someone tell me why I am getting run time error on test case 2: Python3 --> [submission:85214254] ? ~~~~~ When I see the test case it is like 64 3125 1829 -2695 435 632 2042 202 ... I don't know why one line is missing at last? Thanks in Advance ~~~~~

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Codeforces Round #837 should be unrated? Today's problem B : [https://codeforces.me/contest/652/problem/C](https://codeforces.me/contest/652/problem/C) <br> Isn't it the case of stealing/copying a problem? The problem statement was changed only, the problem remains completely the same.<br> So will it be unrated? Or the copying rule was only for Indian authors?

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Contest Based on Brain Craft Intra SUST Programming Contest 2023 Hello, Codeforces! The flagship contest of SUST is here everyone! There will be 12 problems and the problemset is based on **Brain Craft Intra SUST Programming Contest 2023**. We cordially invite you to participate in this contest. Also, we encourage you to participate as teams. Please make sure that you read ALL the problems! The contest will be held on [contest_time:104283] and will run for 5 hours. The setters of this contest are: [user:Alfeh,2023-04-06], [user:Kawchar85,2023-04-06], [user:Mac_prime,2023-04-06], [user:magic_kiri,2023-04-06], [user:nh_nayeem,2023-04-06], [user:Raiden,2023-04-06], [user:ShikariSohan,2023-04-06], [user:ShinnirKolaChori,2023-04-06], [user:susmoydhar7,2023-04-06], [user:Tahseen,2023-04-06] Contest link: [Contest Based on Brain Craft Intra SUST Programming Contest 2023](https://codeforces.me/contests/104283) **UPD:** Congratulations to the winners of the round! Top 5 of all participants: <table style="border-collapse:collapse;borde...

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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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First Ever Users to Reach Some Rating Milestones Revised: ratings below 1500 and greatest rises Several days ago I published a [table](https://codeforces.me/blog/entry/104320) with first people to reach certain ratings. It featured only ratings above 1500, and [user:adamant,2022-07-09] advised to do the same, but on achieving ratings below 1500. I found it quite interesting, and, after several days of collecting data about participations of 447911 Codeforces users, I finally made this table. [cut] For several reasons I firstly put another table. This is the table of greatest rating rises in the history of Codeforces. The reasons are: 1. I have collected so much data from Codeforces that it would be blasphemy not to use it in as many ways as possible. 2. These tables might intersect a lot: it's easier to get a terrific rise in ratings if you are low-rated. (Many people abuse this and deliberately get very low-rated to make a great jump.) 3. Someone recently posted a table with greatest rating rises and falls. I wasn't able to find this table to check whether it was...

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