feel like something from a nightmare., . It felt like all the best qualities one could imagine in a mother converged in her. I don't know any, Hello, Codeforces. Friends. I apologize, but today I will be a bit chaotic and mix personal with, I apologize, but today I will be a bit chaotic and mix personal with public. It just happened that, I want to enter another world. A world free from the insoluble problems of human ambition.A world, She had glioblastoma. It's an aggressive brain cancer that affects only a few people out of 100,000, You may perceive this as a whim of mine, but now I don't want to see topics here that are

Congratulations: Tourist has reached a rating of 4000!, on this incredible achievement! Right now, we have assigned a new rank “Tourist” to the 4+ rating, Feel free to propose your own options and add <a href="/blog/entry/98347">(likes:n)a> (use square, Here are a few options from me. Please, vote:, However, in the future, I would like to change this name to something a bit more neutral (or leave, Right now, we have assigned a new rank “Tourist” to the 4+ rating. This highlights the uniqueness

been feeling is a need for a comprehensive topic list that will contain all sorts of topics from easy, beginning what I have been feeling is a need for a comprehensive topic list that will contain all sorts of, #### About the Topic List I have added a few tutorials for each topic. You can also find more of, #### Payment You can pay me just by upvoting this blog and by being a better programmer and human, Best wishes, my friend <a href="https://emoji.gg/emoji/8771_blobheart">, I have attached my template for each topic. You may not call it a template because some of them, If you are a beginner then just learn basic topics and solve problems.

match of SRM felt like a once-in-a-life event. A lot of legends were competing there &mdash, For now, I'll get some rest for a while, live a calm, non-competitive life, and gradually think, I started my career as a competitive math-puzzle solver in 1999. The first contest wasa local one, It was a great experience. I'd like to thank everyone involved in the community, especially:, Recently, I feel I've passed my peak as a competitive programmer, and ran out of sufficient energy, Then I became an admin, first at TopCoder, then at AtCoder. Especially in AtCoder, I hada right

- 30 best participants get a t-shirt. - 20 t-shirts are randomly distributed among those with, It is the fifth round of a new series of [Codeforces Global Rounds](https://codeforces.me/blog

[user:Urvuk3,2021-10-26] for testing the round. - [user:dorijanlendvaj,2021-10-26] for providinga, make it more by just solving more problems!). I am a student, so pardon me if that's too little., . - [user:dorijanlendvaj,2021-10-26] for providing a test case which will potentially prevent few wrong, Also, thanks for being a part of this. You have just helped someone who is in need (I mean after I, Good Luck! Love you <a href="https://emoji.gg/emoji/8771_blobheart">, I will update you again when I get the money from Codeforces, more likely after a few months as I

$a\bigoplus b \leq a+b$ , $a_i$ is a piecewise linear function and the slope of $a_i$ will only, 100010 int x[MAXN],y[MAXN],a[MAXN],degree[MAXN]; int n,m; void work() { cin>>n>>m; for (int i=1;i, If interval $A,B$ are all good and $A \cap B \neq \emptyset$, then $A, If the result is $x$, then Alice will end the game when Bob moves to a, Let's call position $j$ a key position if it is the center position, See the party as a graph. , Since $k+1$ does not divide $k$, a permutation with weight equal to, Thus, Alice can only move to a certain subset of cells, and the same, call it $I$), so does a row. Let's call a column white if only white cells of it are in $I$, otherwise, draw a beautiful picture using row stripes. , draw a beautiful picture using such algorithm:, edges and cells form a bipartite graph., properties of a rain that, if erase, makes it valid? , vertex, then any unvisited neighbor of $P$ still matches with other unvisited vertices. If $P$ hasa, $ does not divide $k$, a permutation with weight equal to $1$ is: $[n,1,2,\cdots,n-1]$., $a=cnt_{100}+cnt_{101}+cnt_{110}+cnt_{111}$, $a\bigoplus b + a\bigoplus c > b \bigoplus c \iff cnt_{011}+cnt_{100}>0$, $a\bigoplus b = cnt_{010}+cnt_{011}+cnt_{100}+cnt_{101}$, $a\bigoplus c = cnt_{001}+cnt_{011}+cnt_{100}+cnt_{110}$, ). Now the white cells form a "decreasing histogram". We can still find the starting cell $(va,vb)$., Case1: $I$ does not contain $x$ or does not contain $y$, and at least one of $a ,b$ is in $(R_x,L_y)$., Check if one can draw a beautiful picture with row stripes only or with column stripes only. We, Finally, you will get a valid tree., If $[a,b]$ becomes connected after the linking, since we only add edges in $[x,y]$, $[a,x]$ and $[y, If $n$ is even, then such a condition is enough., If $y \geq 1$, then only deleting one vertex with an odd degree would lead to a not worse answer, If there is a pair of toroidal neighbors with different colors. For example, $col_{x,y}=a$ and, Let $I=[a,b]$ not be connected before performing the operation on $[x, y]$ and become connected, Now we fix the number of white columns as $i$, and try to find a $j$ that maximizes $|I|$. If we, Now, we know that if we copy a cell $1000$ times and copy the edges as well, this problem is, One can check that the region of $(x, p)$ satisfying such an inequality is a quadrant rotated $45, One can iterate over all possible solutions with such a structure and take the optimal one., Otherwise, we add a vertex $P$ with the only edge $(P,H)$, move the initial cell to $P$, swap the, Since $[a,x],[x,y],[y,b]$ are all good, $[a,b]$ is good and we are happy., Since $[x,y]$ has been merged into a larger connected component, then there must bea series of, Using binary search on the answer, you can solve the whole problem in $O((n+m)\logA+n\log n+m\log, We say that a position $j$ is valid if $a_j\le m$., When $a,b$ are in different CC, $I$ does not contain both of $x$ and $y$ while they are the key, When $a,b$ are in the same CC, the link will have no influence on its connectivity., ]$ into a larger connected component., bool check(int x){ ll sm=0,f1=0,f2=0; for(int j=m,i=0;j>=1;--j){ while(ia [i+1]+b[j]<=x, case3: $b \leq R_x$ or $a \geq L_y$., e.g. $a=(10)_2,b=(11)_2,c=(01)_2$ then $cnt_{110}=(10)_2,cnt_{011}=(01)_2$, other $cnt$ is 0., int n,m,va,vb; int a[N],b[N]; int da[N],db[N];, template void ckmx(T &A,T B){ AA=B:B; }, void Main(){ cin>>n>>m; for(int i=1;i<=n;++i) cin>>a[i]; for(int j=1;j<=m;++j) cin>>b[j, }); diff.push_back({x[i],-2}); diff.push_back({x[i]+p[i],1}); } sort(diff.begin(), diff.end()); LLa, ~~~~~ #include using namespace std; #define MAXN 100010 int n,m,k; int a[MAXN

of this round is déjà vu! I would like to thank the following people: - <a class="rated-user, - <a class="rated-user user-red" href="https://images.emojiterra.com/twitter/512px/1f921.png" title

one of the two authors, it was not a coincidence. For this reason, the **div1 part of the round is, A final personal remark: I feel sad. Please future authors: do not copy problems. It'sa waste of, Sometimes known problems appear in a contest, it happened to me as an author and to any problem, The div1E problem was copied by one of the two authors, it was not a coincidence.

A difficulty of a problem is also displayed when choosing problems in a mashup., For convenient search of problems in the archive, you can now use a special widget:, For example, if the rating of a problem is less than yours by 200, then the expected probability of, Hi Codeforces! Meet a small innovation on Codeforces — difficulties of problems (and at, Meet a small innovation on Codeforces — difficulties of problems (and at the same timea new

working on the last few days. Now, if a problem uses test cases and its validator is written in, . If a validator is used using the `setTestCase` feature, then this improvement can be applied to, In order to support this, I had to tinker a lot. I made changes to [testlib.h](https://github.com, Just follow the link and see how beautiful it turned out: <a href="https://codeforces.me/contest, Look what an interesting thing I've been working on the last few days. Now, if a problem uses test

be a combined rated round for both divisions. This round is a mirror of VK Cup 2021 Elimination, /92951) задач A-E на английском языке. **UPD3**: В [разборе](https://codeforces.me/blog/entry, This round is a mirror of VK Cup 2021 Elimination. VK Cup is an annual championship for Russian, Welcome to the [contest:1530] that will start on [contest_time:1530]. It will be a combined rated, [Editorial](https://codeforces.me/blog/entry/92951) of problems A-E is out, problems F-H will, Выложен [разбор](https://codeforces.me/blog/entry/92951) задач A-E на английском языке.

- _As a tester, this round gave me PTSD._ - _As a tester, I am, - 30 best participants get a t-shirt. - 20 t-shirts are randomly distributed among those with, It is the third round of a 2020 series of [Codeforces Global Rounds](/blog/entry/65002). The rounds, The problems of this round were prepared by a team of authors: [user:adamant,2020-07-01

should be regarded as a symptom of the fact that Codeforces outgrew the youth phase and entered, Apparently, such an attack should be regarded as a symptom of the fact that Codeforces outgrew the

also be a substantial difference: - Different problems The problems of this round have been, But there will also be a substantial difference:

from $0$ to a value in the region of $500$ (plus or minus $300$ approximately). * Thus, before the, * We are reducing the starting rating from $1500 $ to $ 1400$, so that new accounts makea smaller, , the rating is likely to increase from $0$ to a value in the region of $500$ (plus or minus $300, Apparently, a similar idea is used on AtCoder, but I don't know the details.

sure that you know the password of your Codeforces account. If you don't remember it, just use <a, **UPD:** Now you can enter minimalistic websites without a password. In this case, an email witha, As I wrote into a comment, last round we are faced with a strong DDOS-attack which ruined the, Hello. As I wrote into a comment, last round we are faced with a strong DDOS-attack which ruined, I spend a lot of time to be ready for such incidents.

Enter one or more lines. Each line specifies requirements for a single problem. A line must , (use tags: and provide a comma-separated list of tags, e.g., tags:dp, binary, * Exclude problems that registered mashup participants have solved/attempted/authored (a problem, >"p ratings:2000-2400": a problem with a difficulty level between 2000 and 2400, with the, Hello, Codeforces! Only a couple of days remain until 2025. To wrap up the year, I'm bringing an, Now, you can automatically find and add random problems for your mashup based on a range of, Only a couple of days remain until 2025. To wrap up the year, I'm bringing an update — I hope, When you click the "Find Problems" button, you'll be presented with a list of problems to add. You

maintaining the system and (most importantly) running rounds for a long time to come. But there's, this means a lot to me personally, and I'm proud that now, more than 16 years after that first, This helps with every round we run and gives us a chance to do new things, too. I'm glad to share, a long time to come.

input for writing solutions is a problem statement in English., witnessing a confrontation between [user:tourist,2022-02-02] and AI in near future. What do you think?, ; width:300px; margin:0;"/> Hello, community. Today DeepMind announced a new achievement of AI, Today DeepMind announced a new achievement of AI. And it is directly related to what we love &mdash

unsure whether a particular AI use violates the rules, please consult the competition organizers., * You may not input the problem statement, its summary, any excerpt, or a sub-problem into an AI, , Llama, Claude, and others) for solving programming problems. However, we recognize that AI can bea, . If a round is unrated and this is explicitly stated in the round announcement or rules, the rule, ., after receiving a rejected verdict like "Runtime error on test 1" or similar, you are prohibited from, However, we recognize that AI can be a valuable tool for learning and coding assistance, so we aim

[user:Kuroni,2020-05-01] for being so spectacularly bad that a barely-orange user like myself actually, also a bug that gave us trouble in answering your questions. I'm sorry if you askeda question that, when a final decision on scheduling has been made. It is sad that my contest is delayed, but let's be, - Q: Is it rated? - A: Yes.

,2024-01-02], [user:pavement,2024-01-02], [user:bensonlzl,2024-01-02] for testinga subset of the, - A: [user:Spawnpoint,2024-01-07] - B: [user:tourist,2024-01-07] - C: [user:tourist,2024-01-07, ], [user:bensonlzl,2024-01-02] for testing a subset of the problems in 2022. - [user:MikeMirzayanov,2023

<a href="/edu/courses" style="text-decoration:none; font-size:18px, interface, we announced a new educational subsection of the website. It's time to go international, that someday EDU will become a real educational hub for fans of programming competitions. It will be, , a group of ITMO lecturers and students will be engaged in a pilot course, a little later we will, In February, in the Russian-language interface, we announced a new educational subsection of the, So far, only a pilot course with the first lesson "Suffix Array" has been presented to your

2025 comes to an end. However square the year was, we held a number of rounds: 29 Div. 1 and 31 Div, Hi Codeforces! 2025 comes to an end. However square the year was, we held a number of rounds: 29, I'd like to say a huge thank you to every active community member who created and/or prepared

2025 with duels and live streams. It will be a small, friendly tournament. Its primary goal is to, ago. It's a great idea, and I'd love to do it again! Right now, there are some organizational and, first version of Codeforces on a server, registering my account, and writing the first post. 15 years, platform for programming smart contracts on the TON network! I think this will bea fresh and exciting, their long-term and consistent support of the competitive programming community isa great gesture of, with screen-sharing and webcams. If you're red (or have been red) and are interested in giving ita, . What's amazing is that it was never a lonely journey. I've always had caring and reliable friends, Around this time, 15 years ago, I was deploying the first version of Codeforces ona server, On a day like this, of course, I want to share some good news. And we have some! We have fantastic, That's all for now, I think. And now I'll go enjoy a piece of birthday cake.

receives is fair and well-deserved. But there is a fine line between criticism, saying that you, want to take it out on the community as a whole or someone specific. And if I createda blog for, website. And this is sometimes a good thing; but it can also make people think that ifa high-rated, **UPD2:** Initially, there was a link to the comment which caused me to write this whole blog (a, But there is a fine line between criticism, saying that you didn't like the problems, and hurling

that this can dramatically increase judging time (and leads to a huge queue). I don't want to risk the, . My recent tests show that this can dramatically increase judging time (and leads toa huge queue). I

"solve a lot of problems" and that's true, there's no other way. Anyway, I've thought about it and, Saturday, universities organize ICPC training contests once a week, people try by their own to solve, good to practice a bit now" or "oh, it'd be cool to solve every problem on this website, let's start, when you ask someone good about how to practice, he/she will reply to you to "solvea lot of, Do you really want to get better and compete virtually in two 5-hour contests in a row? Great, go, Do you want to participate in a virtual round? Sure, go and do this. Don't do this if you are sure, Do you want to simply solve a few problems? Great, go and solve them as long as they are, Do you want to skip a training organized by the university and meet your friends/reada book/play, Every really good person gave a part of their life to CP. And I don't mean giving up Saturday, I don't know what's more to say. Don't give up? With the right attitude, if you can't solvea, One more time: you really have to have CP in your mind. After solving a problem, it doesn't mean, So yeah, that's my opinion. Let CP get into your mind and find a true desire to practice. Don't try, Want to go and participate in a training organized by your university? Of course, great idea &mdash

A: [user:LiM_256,2021-07-29], at $0$ mins! B: [user:RinShima,2021-07-29], at $4$ mins! , a bit difficult than usual.

this, you should add the stream to the site using a special section in your profile. Please, note, For example, right now there is a [user:Errichto,2020-10-21]'s stream announcement in the sidebar., Shortly before the start of the stream, a notification about the upcoming stream will appear in the, a special section in your profile. Please, note that when adding a Twitch stream, you just need to

; float:right; margin: 0 1.5em 1.5em 1.5em"/> I am happy to wish you a Happy New Year! I wish youa, I am happy to wish you a Happy New Year! I wish you a great, bright, interesting New Year! Just

greater, Codeforces is going to host a contest and I will be an author of all tasks. Hello 2019 will, - A: [user:Errichto,2019-01-05] - B: [user:dorijanlendvaj,2019-01-05] - C: [user:Um_nik,2019-01, The round will consist of 8 problems and you will be given two and a half three hours to

had a break for some years. There is always a lot of work happening behind the scenes, invisible to, , or you don't care about replies to a particular comment. So now you can toggle comment tree, If you have an idea of a small and simple improvement for Codeforces, let us know in the comments!, Since recently I have rejoined Codeforces dev team. I worked on it before but hada break for some, There is always a lot of work happening behind the scenes, invisible to the users, but sometimes it, Today, we have a couple improvements for the comment section.

I'm just in a mood to shitpost. Don't take it too seriously.

and good. Let this wish come true! We have had a large number of rounds this year. I hope we, it will be possible to roll back the changes or change the handle again only _aftera year_. Be, you before. The links to a profile page with an old handle would automatically redirect to the, Again, this year if you took part in at least 10 rounds you can request a handle of an _inactive_, Talking about handles I always reminisce the following story. Once a user wrote me the, We have had a large number of rounds this year. I hope we have pleased you with interesting

gave up not only on solving them independently, but even on making a serious effort to understand the, # A small announcement, I make this material available as a benefit of paid GitHub Sponsors tiers. Please check the public, Personally, I think it is a very simple and universally understandable goal, comparable to the, There were also cases where I used methods that would not normally be allowed duringa contest, a special explanation?

knowledge in a real contest. Since even in the Div. 2 rounds regularly some Div. 1 users register new

character can be a lowercase letter, an uppercase letter, a digit, a comma... basically, it can be any, different. Let's say that we've assigned $0$ to $a$. Then we have to assign $1$ to $b$. Then we have to, Please, note that this task comes from the contest which took place a few years ago, so don't think

- Q: Is it rated? - A: Yes

made a blog about CF Called “I Miss the Old CF," man that would be so CF