Matrix Exponentiation tutorial + training contest tl;dr — video tutorial https://www.youtube.com/watch?v=eMXNWcbw75E and codeforces GYM training https://mirror.codeforces.com/gym/102644 (register by finding this contest in GYM instead of using the link directly) video editorial: [part 1 (ABCDEF)](https://www.youtube.com/watch?v=kQuCOFzWoa0) and [part 2 (GHI)](https://www.youtube.com/watch?v=RA_SpxP2t54) codes to all 9 problems: https://github.com/Errichto/youtube/tree/master/matrix-exponentiation Prerequisites: binary exponentiation and iterative dp (you don't need to know matrices) The youtube tutorial ([link](https://www.youtube.com/watch?v=eMXNWcbw75E)) focuses on intuition and graph-like visualization . Or, if you prefer, below is a shorter (less detailed) text tutorial instead. You can practice by solving a set of 9 educational problems in GYM https://mirror.codeforces.com/gym/102644. ABCD are easy, EF medium, GHI are hard. If you are stuck, see hints below or watch the full solution analysis — [part 1 (ABCDEF)](https:...

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Catalan Numbers and Generating Uniform Balanced Bracket Sequences Hi everyone! Today [user:nor,2022-05-27] sir and I would like to talk about generating uniform bracket sequences. Over the past few years when preparing test cases, I have had to generate a uniform bracket sequence a few times. Unfortunately I could not figure out how, so I would like to write a blog about this now. Hopefully this blog would be useful to future problem setters :) Scroll down to the end of the blog to copy our generators. First, let's define some things. A bracket sequence is a string with $n$ $\texttt{(}$ s and $n$ $\texttt{)}$ s. A **balanced** brackets sequence is a bracket sequence with the additional constraint that it becomes a valid arithmetic expression when we add some $\texttt{1}$ s and $\texttt{+}$ s. Let $p$ be the prefix sum array of a bracket sequence (we assign $1$ to $\texttt{(}$ and $-1$ to $\texttt{)}$ and take the prefix sum). For example, if our bracket sequence is $\texttt{())()((())}$, then $p=[1,0,-1,0,-1,0,1,2,1,0]$. An alternate way to thi...

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Codeforces Round #273 English Editorial (C is available now!) Hello everyone. I have noticed the absence of round 273's editorial, so I decided to write one. This is the first time I write an editorial, so hope everyone like this! I didn't know how to solve C and E yet, so it would be appreciated if someone help me with these problems. Also, how to use LaTex in codeforces? I want to use this so my editorial would be more clear to read. **UDP:** Actually, there's a (well-hidden) tutorial for this round, but it's written in Russian (with a English version using google translate in comment section). If you can read Russian, [click here](http://mirror.codeforces.com/blog/entry/14307#comment-192751). **UDP2:** Problem C is now available! A — Initial Bet =============== Since the coin only pass from this player to other player, the coins sum of all player won’t change in the game. That mean, we’ll have `5*b = c1+c2+c3+c4+c5`. We’ll put `sum = c1+c2+c3+c4+c5`. So, if `sum is divisible by b`, the answer will be `sum/b`. Otherwise, the ans...

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[Tutorial] Range minimum query in O(1) with linear time construction <spoiler summary="TL; DR"> Build a sparse table over blocks of size $b = 30 \geq \log{n}$. Now we only need to answer queries of size smaller than $b$. For that, simulate a minqueue of size $b$ over the array, and store a mask of the elements that are currently active in the minqueue. Let $\text{mask[r]}$ be the minqueue mask when the simulation is at position $\text{r}$. Now we can see that, if $r-l+1 \leq b$, then `query(l, r) = r - most_significant_set_bit(mask[r] & ((1<<(r-l+1))-1))`. ~~~~~ template<typename T> struct rmq { vector<T> v; int n; static const int b = 30; vector<int> mask, t; int op(int x, int y) { return v[x] < v[y] ? x : y; } int msb(int x) { return __builtin_clz(1)-__builtin_clz(x); } int small(int r, int sz = b) { return r-msb(mask[r]&((1<<sz)-1)); } rmq(const vector<T>& v_) : v(v_), n(v.size()), mask(n), t(n) { for (int i = 0, at = 0; i < n; mask[i++] = at |= 1) { at = (at<<1)&((1<<b)-1); while (at and op(i, i-msb(at&-at)) == i) at ...

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Educational Codeforces Round 75 [Rated for Div. 2] Hello Codeforces! On [contest_time:1251] [contest:1251] 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 **7 problems** and **2 hours** to solve them. The problems were invented and prepared by Roman [user:Roms,2019-10-23] Glazov, Adilbek [user:adedalic,2019-10-23] Dalabaev, Vladimir [user:Vovuh,2019-10-23] Petrov, Ivan [user:Bl...

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Codeforces Round #498 (Div. 3) Hello! Finally I am freed from the big part of summer cares and I can continue the preparation of Div. 3 rounds! I decided to add something written by me to this blog because [user:TryToKnowMe,2018-07-15] (and many others, i think) [noticed](https://mirror.codeforces.com/blog/entry/60377?#comment-442051) that i am really copy and paste this text from one announcement to another changing only contest name and start time. But... Who knows, may be this time which is saved by copy-pasting the announcement allows me to prepare the problems better?... Let it stay a mystery. So, let's go. [contest:1006] will start at [contest_time:1006]. You will be offered 6 problems with expected difficulties to compose an interesting competition for participants with ratings up to 1600. Probably, participants from the first division will not be at all interested by this problems. And for 1600-1899 the problems will be too easy. However, all of you who wish to take part and have rating 1600 or higher, can re...

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Codeforces Round #273 (Div. 2) :: разбор задач [problem:478A] Для решения задачи важно заметить, что в ходе игры количество монет на столе меняться не может. Суммарное количество монет на столе после того, как сделаны ставки, остается неизменным. Следовательно, разделив суммарное количество монет на столе на количество игроков, можно получить начальную ставку каждого из них. Если разделить без остатка невозможно, то такой итог игры невозможен. Стоит обратить внимание на то, что начальная ставка каждого из игроков должна быть отлична от нуля, следовательно, ноль никогда не может являться ответом. [problem:478B] Если переформулировать задачу в терминах теории графов, то ее можно сформулировать следующим образом: Имеется граф, состоящий из $n$ вершин и $m$ компонент связности. Внутри каждой компоненты связности каждая пара вершин этой компоненты связана ребром. Другими словами, каждая компонента связности является полносвязной. Какое наименьшее и какое наибольшее количество ребер может содержать такой граф? Рассмотрим проце...

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Invitation to TOKI Open 2018 Hello! After we successfully organized [TOKI Open 2014](http://mirror.codeforces.com/blog/entry/12286) and [TOKI Open 2017](http://mirror.codeforces.com/blog/entry/51512), we are going to do the similar thing this year. We will open our current IOI Selection Contest to international participants. We call it **TOKI Open 2018**. TOKI stands for Tim Olimpiade Komputer Indonesia, or Indonesian Computing Olympiad Team in English. Objectives of us opening this contest include, but not limited to: - Measure the performance of our IOI trainee compared to other countries' IOI trainee. - Foster friendship between Indonesia and other IOI participating countries. - Test Indonesia's scientific committee capability in setting IOI-level problems. - Test Indonesia's technical committee capability in hosting IOI-level contests. The contest will have very similar format with IOI, as this contest will be used to select our Top 4 and train our Top 4 for IOI. We expect that the difficulty of the contest i...

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Educational Codeforces Round 52 [Rated for Div. 2] On [contest_time:1065] [contest:1065] will start. [cut] 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,2018-09-19] Glazov, Adilbek [user:adedalic,2018-10-11] Dalabaev, Vladimir [user:Vovuh,2018-10-11] Petrov, Ivan [user:BledD...

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【LGR-273】Luogu Round 273 Announcement We will hold Luogu Round 273 on Luogu. This is a Div.1/2 round. English statement will be provided officially. You can click the button to change language.  - Contest URL: - Div.1: <https://www.luogu.com.cn/contest/309087> - Div.2: <https://www.luogu.com.cn/contest/309086> - Start Time: [03.01 14:00(UTC+8)](https://www.timeanddate.com/worldclock/fixedtime.html?iso=20260301T1400&p1=237) - Duration: 240 minutes - System: IOI - Difficulty: CF Div.1/2 - Staffs: [user:vinstag173,2026-02-28], [user:dottle,2026-02-28], [user:_istil,2026-02-28], [user:OIer1048576,2026-02-28], [user:mrsrz,2026-02-28], [user:zlxfth,2026-02-28] - Rated range: Div.1 unlimited. Div.2 <=2000 rating on Luogu - Score distribution: 100-100-100-100 We are looking forward to your participation! - [A tutorial on using Luogu](https://mirror.codeforces.com/blog/entry/131261) (...

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Codeforces Round #273 (Div. 2) Всем доброго времени суток, [16 октября 2014 года в 19:30 MSK](http://www.timeanddate.com/worldclock/fixedtime.html?msg=Codeforces+Round+%23273+%28Div.+2%29&iso=20141016T2230&p1=1915&ah=2) состоится очередной раунд Codeforces #273 для участников из второго дивизиона. Традиционно, участники из первого дивизиона могут участвовать в соревновании вне конкурса. Автор задач: [user:KhaustovPavel,2014-10-15] (Хаустов Павел, Россия, Томск, Томский ПУ) За подготовку раунда отдельное спасибо коллективу [Codeforces](http://mirror.codeforces.com) и, в частности, Максиму Ахмедову ([user:zlobober,2014-10-15]) за помощь в подготовке и Марии Беловой ([user:Delinur,2014-10-15]) за перевод условий задач на английский язык. Участникам будет предложено пять задач и два часа на их решение. **Распределение баллов по задачам: 500-1000-1500-2000-2500** **UPD: Старт сдвинут на 10 минут** Желаю удачи всем участникам!

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Panasonic Programming Contest 2022(AtCoder Beginner Contest 273) Announcement We will hold Panasonic Programming Contest 2022(AtCoder Beginner Contest 273). - Contest URL: https://atcoder.jp/contests/abc273 - Start Time: http://www.timeanddate.com/worldclock/fixedtime.html?iso=20221015T2100&p1=248 - Duration: 100 minutes - Number of Tasks: 8 - Writer: [user:leaf1415,2022-10-15], [user:physics0523,2022-10-15], [user:m_99,2022-10-15], [user:Nyaan,2022-10-15] - Tester: [user:math957963,2022-10-15], [user:nok0,2022-10-15] - Rated range: ~ 1999 The point values will be 100-200-300-400-500-500-600-600. We are looking forward to your participation!

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Educational Codeforces Round 34 [Rated for Div. 2] Hello Codeforces! On [December 12, 18:05 MSK](https://www.timeanddate.com/worldclock/fixedtime.html?day=12&month=12&year=2017&hour=18&min=5&sec=0&p1=166) Educational Codeforces Round 34 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** again. 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 Mikhail [user:PikMike,2017-11-08] Piklyaev, Ivan [user:BledDest,2017-11-22] Androsov and me. Good luck to all participants! I also have a ...

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Help wanted on solving problem 273A or 272C using Haskell! This problem is easy to solve using other languages with or without the help of segment tree. But as I am learning Haskell, I tried to solve it with segment tree using Haskell. However, after a lot of tries, I found it impossible for me to solve it. So I need your help. I would be glad if you can point out any error in my submission or you can show me a Haskell solution (with the help of segment tree that support updating an interval) to this problem or let me know why it cannot be solved this way. Thanks! **UPD1:** My submission: [here](http://mirror.codeforces.com/contest/273/submission/4059422) **UPD2:** Another submission of mine (after reading [Data.SegmentTree](http://hackage.haskell.org/packages/archive/SegmentTree/0.2/doc/html/Data-SegmentTree.html)): [here](http://mirror.codeforces.com/contest/273/submission/4060619) **UPD3:** [user:adamax,2013-07-14]'s submission(Accepted. However, I think it doesn't take the advantage of Haskell.): [here](http://mirror.codeforces.com/contest/273/s...

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Matrix implementation allowing brace-enclosed initializer list in C++ When solving a matrix exponention task I found myself wanting to overload the multiplication operator and to able to initialize a matrix like I would initialize a short vector with known values, i.e., `vector<int> vec = {1,2,3};` Inheriting the struct from `vector<vector<int>>` seemed useful. Not only that would allow for easy initialization it would also provide access to [] operator and many other useful vector methods. I discovered that the constructor is not inherited :( There is however a workaround introduced in C++11 described on [stackexchange](https://softwareengineering.stackexchange.com/questions/197893/why-are-constructors-not-inherited). The final struct looks something like this: ~~~~~ struct Matrix:vector<vector<int>> { // "inherit" vector's constructor using vector::vector; Matrix operator *(Matrix other) { int rows = size(); int cols = other[0].size(); Matrix res(rows, vector<int>(cols)); fo...

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Dynamic Programming Type <u>Dynamic Programming (DP) :</u><br><br><b>1. Classic Dynamic Programming</b><br>a. <a href="http://en.wikipedia.org/wiki/Longest_common_subsequence_problem">LCS</a><br>&nbsp;&nbsp; Problem: 1. <a href="https://www.spoj.pl/problems/SAMER08D/">SAMER08D<br></a><br>b. <a href="http://en.wikipedia.org/wiki/Longest_increasing_subsequence">LIS</a><br>&nbsp;&nbsp; Problem: 1. <a href="http://acm.sgu.ru/problem.php?contest=0&amp;problem=199">Beautiful People</a><br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 2. <a href="http://www.spoj.pl/problems/MDOLLS/">MDOLLS</a><br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 3. <a href="http://www.spoj.pl/problems/MSTICK">MSTICK</a><br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 4. <a href="http://www.spoj.pl/problems/MCARDS/">MCARDS</a><br><br>c. <a href="http://en.wikipedia.org/wiki/Edit_distance...

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Indigo Contest 2023 Unofficial Editorial As the official editorial is promised to come out later, I will write an unofficial editorial for now. Some of the solutions are from my teammate [user:tcmmichaelb139,2023-04-17] orz. Contest: https://www.hackerrank.com/indigo-coding-competition ## Easy These problems are quite trivial, so I will only provide solutions: <spoiler summary="P1"> ~~~~~ n=int(input()) arr=[] for i in range(n):arr.append(input().strip().replace('x','')) for i in range(n): cnt=arr[i].count('y') arr[i]=arr[i].replace('y','') arr[i]+=cnt*'y' arr=sorted(arr,key=lambda x:(-len(x),x)) print('\n'.join(arr)) ~~~~~ </spoiler> <spoiler summary="P2"> Michael's solution: ~~~~~ #include "bits/stdc++.h" using namespace std; string pi = "31415926535897932384626433832... (truncated copy-paste from internet)"; void solve() { string s; cin >> s; for (int i = 0; i < s.length(); i++) if (s[i] != pi[i]) { cout << i << '\n'; r...

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CF Doctor : A cross-platform no-code CLI for real-time stress testing [Demo](https://github.com/variety-jones/cfdoc/blob/master/cfdoc-demo.gif), [Download Instructions](https://github.com/variety-jones/cfdoc/tree/master) **CF Doctor** is a **cross-platform, no-code** CLI for **real-time** stress testing. It can help you find the **smallest** possible **counter-example** for your failing submission, right from the comfort of your terminal. It does everything that [cfstress](https://mirror.codeforces.com/blog/entry/99278) does and more. ### Features * **Customizable** : It offers the highest level of customization. For example, you can say, > Give me a counter example containing 273 testcases. Also, for each testcase, the array length should be in the range $[23, 35]$ and each array value should be in the range $[57, 63]$. * **Fast** : It can evaluate your code on $10, 000$ small test cases within $60$ seconds to generate a counter example. * **Light Weight** : The portable binary is only around $12$ **MB** in size. * **Effective** : Out of the $50...

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Dynamic Programming links This is from [user:Harta,2015-03-13]'s blog [here](http://mirror.codeforces.com/blog/entry/325) Some of the links were broken, so I wanted to update the ones which are still available. Dynamic Programming (DP) : -------------------------- ### Classic Dynamic Programming #### I. [Longest Common Subsequence (LCS)](http://en.wikipedia.org/wiki/Longest_common_subsequence_problem) 1. [SAMER08D](http://www.spoj.com/problems/SAMER08D/) #### II. [Longest Increasing Subsequence (LIS)](http://en.wikipedia.org/wiki/Longest_increasing_subsequence) 1. [Beautiful People](http://acm.sgu.ru/problem.php?contest=0&problem=199) 1. [MDOLLS](http://www.spoj.com/problems/MDOLLS/) 1. [MSTICK](http://www.spoj.com/problems/MSTICK/) 1. [MCARDS](http://www.spoj.com/problems/MCARDS/) #### III. [Edit Distance](http://en.wikipedia.org/wiki/Edit_distance) #### IV. [Matrix Chain Multiplication](https://en.wikipedia.org/wiki/Matrix_chain_multiplication) 1. [Mixtures](http://www.spoj.com/problems/MIX...

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Республиканская олимпиада 2026 года. Казахcтан. Результаты. <spoiler summary="Результаты прошлых лет"> [2025](https://mirror.codeforces.com/blog/entry/140577) [2024](https://mirror.codeforces.com/blog/entry/127605) [2023](https://mirror.codeforces.com/blog/entry/114266) [2022](https://mirror.codeforces.com/blog/entry/102044) [2021](https://mirror.codeforces.com/blog/entry/90111) [2020](https://mirror.codeforces.com/blog/entry/80808) [2019](https://scoreboard.bc-pf.org/results/informatics/national-olympiad/2019) [2018](https://scoreboard.bc-pf.org/results/informatics/national-olympiad/2018) [2017](https://scoreboard.bc-pf.org/results/informatics/national-olympiad/2017) </spoiler> #### **9 класс** | **Место** | **ФИО** | **CF handle** | **1 тур** | **2 тур** | **Общий** | **Медаль** | |---|---|---| | 1 | Бауыржан Шөкей | [user:Shad_29, 2025-08-27] | 234 | 143 | 377 |  | | 2 | Алишер Еламан | [user:Alish_1_2100,2026-03-22] | 203 | 135 | 338 | ![ ](https://codef...

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Codeforces Global Rounds 2021: Current Results (GR13-GR17) In 2021 (as in 2019 and 2020), with the support of XTX Markets, 6 rounds of the new Codeforces Global Rounds are held: common rounds for both divisions of 7–9 problems each. The duration of the rounds is 2-3 hours, depending on the number and complexity of the problems. All such rounds are rated for all participants. <i>At each such round, 50 brand T-shirts are handed out, and we are happy to give T-shirts to all problem authors.</i> The prizes for the 6-round series in 2021: - 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 five rounds he placed the highest. - The best 20 participants over all series get sweatshirts and place certificates. Current standings after five rounds (sorted by total points in four best placed rounds): | Place | Contestant | = | GR 13 | GR 14 | GR 15 | GR 16 | GR 17| | - | - | - | - | - | - | - | - | | ...

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Codeforces Global Rounds 2020: Final Results In 2020, with the support of XTX Markets, 6 rounds of the Codeforces Global Rounds were held. Each round was common for both divisions. All such rounds were rated for all participants. At each such round, 50 brand T-shirts were handed out, and we gave T-shirts to all problem writers! I say a big thank you to XTX Markets (and personally to Yuri Bedny and Alexander Gerko) for supporting Global Rounds. Without your help, we could not host them! I sincerely admire companies like these who come to support and develop the community that some of their employees come from. It will be great if other companies follow the example and also offer their help. We need it! The prizes for the 6-round series in 2020: - 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...

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Codeforces Global Rounds 2021: Final Results (GR13-GR18) Tomorrow will be the first global round of this year. And we are happy to sum up the results of last season. We announce the results! We remind you that the global rounds are a joint initiative of XTX and Codeforces. We are happy to announce that they continue into the new year. We hold 6 such rounds per year. All of them are open to both divisions. At each such round, 50 brand T-shirts were handed out, and we are happy to give T-shirts to all problem authors. The prizes for the 6-round series are: - 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. The final standings after six rounds (sorted by total points in four best placed rounds): | Place | Contestant | = | GR 13 | GR 14 | GR 15 | GR 16 | GR 17 | GR 18| |--...

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Республиканская олимпиада 2021 года. Казахcтан. Результаты. 2021 : https://mirror.codeforces.com/blog/entry/90111 2020 : https://mirror.codeforces.com/blog/entry/80808 2019 : https://respa.daryn.kz/ 2018 : https://mirror.codeforces.com/blog/entry/58432 2017: https://mirror.codeforces.com/blog/entry/51416 ####9 Класс <html> <body> <style type="text/css"> .tg {border-collapse:collapse;border-spacing:0;} .tg td{border-color:black;border-style:solid;border-width:1px;font-family:Arial, sans-serif;font-size:14px; overflow:hidden;padding:10px 5px;word-break:normal;} .tg th{border-color:black;border-style:solid;border-width:1px;font-family:Arial, sans-serif;font-size:14px; font-weight:normal;overflow:hidden;padding:10px 5px;word-break:normal;} .tg .tg-0pky{border-color:inherit;text-align:left;vertical-align:top} </style> <table class="tg" style="undefined;table-layout: fixed; width: 579px"> <colgroup> <col style="width: 50px"> <col style="width: 160px"> <col style="width: 170px"> <col style="width: 97px"> <col style="width: 102px"> </colgroup...

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Need help in "RED GREEN TOWER" from round 273 Hello guys, i am not able to understand the logic behind [user:flashmt,2015-07-12]'s solution of [problem:478] red-green towers from round 273 . Link to problem :http://mirror.codeforces.com/contest/478/problem/D Link to solution :http://mirror.codeforces.com/contest/478/standings/page/1# . His solution seems to be quite elegant . If you know some similar problems , please tell me . Thanks in advance .

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Codeforces Global Rounds 2019: Final Results In 2019, with the support of XTX Markets, 6 rounds of the new Codeforces Global Rounds were held. Each round was common for both divisions and had 7–9 problems. The duration of the rounds was 2-3 hours, depending on the number and complexity of the problems. All such rounds were rated for all participants. At each such round, 50 brand T-shirts were handed out, and we gave T-shirts to all authors and problem testers as well. 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. Final results: [cut]<br/> | Place | Contestant | = | Round 1 | Round 2| Round 3 | Round 4 | Round 5 | Round 6 | | - | - | - | - | - | - | - | - | - | | 1 | [user:tourist,2019-12-17] | <b> 2987 </b> | ...

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Codeforces Global Rounds 2019: Current Results After Five 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 five rounds: | Place | Contestant | = | Round 1 | Round 2| Round 3 | Round 4 | Round 5 | | - | - | - | - | - | - | - | - | | 1 | [user:tourist,201...

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Exclaimation Mark Why isn't there an editorial for [Codeforces Round #273 (Div. 2)](http://mirror.codeforces.com/contest/478)?! For those who are able to make one.. please don't hesitate.

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Dima and Two Sequences Hi, Here Problem link:[http://mirror.codeforces.com/contest/273/problem/B](http://mirror.codeforces.com/contest/273/problem/B) Here m can be non prime number.How can I handle the division property? I read tutorial[http://mirror.codeforces.com/blog/entry/6625](http://mirror.codeforces.com/blog/entry/6625), but I can't understand properly. Can you reply, thanks

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Help in 478C-Table decorations I have been stuck in this problem [problem:478C] for ages now, i cannot understand the editorial (http://mirror.codeforces.com/blog/entry/18619), why does this work and also i have problem in understanding the binary search approach (https://abitofcs.blogspot.in/2014/10/a-bit-of-cf-codeforces-round-273-div-2.html), somebody please help me by providing a detailed proof!!

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First Ever Users to Reach Some Rating Milestones Revised: ratings above 1500 and greatest falls Several days ago I published a [table](https://mirror.codeforces.com/blog/entry/104320) with first people to reach certain ratings. It was a bit raw because, firstly, it was based on top 20000 Codeforces users by rating, and, secondly, because it only gave information about ratings divisible by 50. Now I have prepared a table that is of more complex design, but both issues are resolved. Good luck understanding what is going on in it. [cut] For several reasons I firstly put another table. This is the table of greatest rating falls 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 fall in ratings if you are high-rated. 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 right, but if someone finds it, you're welcome to pu...

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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://mirror.codeforces.com/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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Milestones: ratings below 1500 and greatest rises (2024 edition) <i>Note.</i> This is an updated version of [this post](https://mirror.codeforces.com/blog/entry/104683). If you like [this style](https://mirror.codeforces.com/blog/entry/104320) more, please tell me in the comments. Since [user:tourist,2024-09-05]'s [breakthrough](https://mirror.codeforces.com/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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