EPIC Institute of Technology Round Summer 2025 (Codeforces Round 1036, Div. 1 + Div. 2) # Hello Codeforces Once Again <img alt="" src="https://mirror.codeforces.com/predownloaded/4e/71/4e713a365fc86888c808b3b56d6fecfb529973e6.png" style="float:right; height: 154px; padding-left: 35px; padding-right: 73px; padding-top: 41px; padding-bottom: 33px;"/> After months of hard work, [user:cry,2025-07-01], [user:Lilypad,2025-07-01] and I are extremely proud to welcome you to participate in [contest:2124] at [contest_time:2124]. This round is combined for Division 1 and Division 2, and it will be rated for everyone. You will be given $3$ hours to solve $9$ problems. One problem will be split into two subtasks. We would like to thank the following people for making the contest possible: - [user:satyam343,2025-07-01] for outstanding coordination, working tirelessly with us to improve problem quality and donating his own problems to us. I cannot thank him enough. - [user:Error_Yuan,2025-07-01] for proposing some ideas that weren't used in the end. - [user:Benq,2025-07-01...

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EPIC Institute of Technology Round Summer 2024 (Div. 1 + Div. 2) <a href="https://epic-institute.io/"><img alt="EPIC" src="https://assets.codeforces.com/images/deltix/2_logo.gif" style="float:right; height: 154px; padding-left: 35px; padding-right: 73px; padding-top: 41px; padding-bottom: 33px;"/></a> Hi, Codeforces! We are pleased to invite you to [contest:1987], which will be held on [contest_time:1987]. You will be given **8 problems**, two of which are divided into two subtasks, and you will have **3 hours** to solve them. The round will be rated for **everyone**. At least one of the problems will be interactive, so please read the [guide for interactive problems](https://mirror.codeforces.com/blog/entry/45307) if you are not familiar with it. We would like to thank: - [user:errorgorn,2024-06-27] for coordinating the round. - [user:Geothermal,2024-06-27], [user:turmax,2024-06-27], [user:noimi,2024-06-27], [user:SomethingNew,2024-06-27], [user:feecIe6418,2024-06-27], [user:Endagorion,2024-06-27], [user:glebustim,2024-06-27], [user:zelibo...

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Codeforces Deltix Round Summer 2021 [Div.1 + Div.2] <a href="https://deltix.io/"><img alt="deltix" src="https://assets.codeforces.com/images/deltix/EcCsUtwbu1yq6Av.gif" style="float:right; height: 400px"/></a> <p>Hi <span style="font-weight:bold">Code</span><span style="color:rgb(71,94,152);font-weight:bold">forces</span>!</p> We are **[DELTIX](https://deltix.io/)**. Founded in 2005, DELTIX is one of the market leaders in software development for financial research and products for systematic and algorithmic trading. In 2020 DELTIX joined the EPAM family. Our mission is to turn promising ideas into breakthrough products fast. We are experts in: * aggregation, storage, and processing large volumes of time-series data * data modeling * testing and deployment of quantitative models In our team we value such skills as: * knowledge of algorithms * high-performance coding * low latency data streams processing We are excited to announce that one of our products [TimeBase Community Edition](https://github.com/finos/...

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Deltix Round Spring 2021 bug - Uphacks counted as real systests It looks like some of Deltix Round Spring 2021 got rejudged to include uphacks, including causing my D to go from passing to failing, and also affecting the placing and rating. You can see in the [announcement](http://mirror.codeforces.com/blog/entry/90915) that I originally got 5th, but the [scoreboard](http://mirror.codeforces.com/contest/1523/standings) now shows 10th, and my submission [submission:117918101] shows an extra 10 tests beyond the 127 that other submissions have, like [submission:117881477]. It seems like this bug is several months old: [user:galen_colin,2021-06-01] posted about it at https://mirror.codeforces.com/blog/entry/88000, and [user:MikeMirzayanov,2021-06-01] didn't fix that contest and said he'd "try to avoid it in the future". This bug is totally unacceptable, it significantly affected results a full 2 days after the contest ended; imagine if it affected prize distribution. I have no idea when these hacks were added, but it's definitely not akin to in-contest hacking. [user...

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EPIC Institute of Technology Round August 2024 (Div. 1 + Div. 2) <a href="https://epic-institute.io/"><img alt="EPIC" src="https://assets.codeforces.com/images/deltix/2_logo.gif" style="float:right; height: 154px; padding-left: 35px; padding-right: 73px; padding-top: 41px; padding-bottom: 33px;"/></a> Hi, Codeforces! We are pleased to invite you to [contest:2002], which will be held on [contest_time:2002]. The problems are prepared by [user:Flamire,2024-08-06], [user:le0n,2024-08-06] and [user:xcyle,2024-08-06]. You will be given **8 problems** and **3 hours** to solve them. Two problems are divided into two subtasks. The round will be rated for **everyone**. We would like to thank everyone who has helped prepare for this round: - [user:TheScrasse,2024-08-06] for his brilliant coordination. - [user:AdunAdunov,2024-08-08] and [user:Alexdat2000,2024-08-08] for Russian translation. - [user:orzdevinwang,2024-08-06], [user:arvindf232,2024-08-08], [user:MagicalFlower,2024-08-06], [user:rui_er,2024-08-06], [user:LipArcanjo,2024-08-06], [u...

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Every Technique and Algorithm I Used to Become Grandmaster Hi everyone, I became grandmaster today so I decided to go down memory lane and review every problem I have ever done in a CodeForces contest to look back and see every technique and algorithm I had to use to become a grandmaster. I am not sure how useful this is, I mostly think it's fun to look at all the old solutions I wrote and how different it was from how I write code now. The main takeaway is that, as many people have said before, you don't need to know or memorize a bunch of advanced algorithms to become grandmaster. As you will see, there are many problems where I just used "ad hoc reasoning," meaning there's not a standard technique I used to solve the problem and you just need to make some clever mathematical observations to solve the problem. Also, there are many popular algorithms that I have never needed in a CodeForces contest despite being a grandmaster: - Sparse tables, Fenwick trees, and segment trees - String algos, like rolling hashes, Knuth-Morris-Pratt, suffix...

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deltixlab’s interview: Deltix rounds back story _I am very glad to introduce my guests from [Deltix](https://deltix.io):_ _Aliaksandr [user:sdryapko,2021-12-10] Drapko, the Head of Technology of [CryptoCortex](https://deltix.io/products/cryptocortex.html) product and_ _Vladislav [user:Vladik,2021-12-10] Vishnevsky, the coordinator of all competitive programming activities by Deltix and the key developer of [MarketMaker](https://deltix.io/products/marketmaker.html) product._ _I am proud to be their compatriot, so let me start with some belorussian words of greetings_ _- Прывiтанне, Аляксандр і Уладзіслаў!_ - Прывiтанне, Наталля! _- Deltix is the sponsor of the Belarus National School Olympiad in Informatics. Last spring you represented Deltix at the National Final award ceremony. The award ceremony was very touching for the winners. But what about you? How did you feel presenting them prizes? What were you thinking about at this moment?_ ![ ](/predownloaded/b9/ef/b9ef3e92cbfd2d50ca984d6870ae9a16fd788db4.jpg...

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Codeforces Deltix Round Autumn 2021 [Div.1 + Div.2] <a href="https://deltix.io/"><img alt="deltix" src="https://assets.codeforces.com/images/deltix/deltix-autumn-2021.gif" style="float:right; height: 400px"/></a> <p>Hi, <span style="font-weight:bold">Code</span><span style="color:rgb(71,94,152);font-weight:bold">forces</span>!</p> We are **[DELTIX](https://deltix.io/)**. Founded in 2005, DELTIX is one of the market leaders in software development for financial research and products for systematic and algorithmic trading. In 2020 DELTIX joined the EPAM family. Our mission is to turn promising ideas into breakthrough products fast. We are experts in: - aggregation, storage, and processing large volumes of time-series data - data modeling - testing and deployment of quantitative models In our team we value such skills as: - knowledge of algorithms - high-performance coding - low latency data streams processing We are excited to announce that we have released [TimeBase Web Admin Community Edition](https://github.com...

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Codeforces Deltix Round Spring 2021 [Div.1 + Div.2] <a href="https://deltix.io/"><img alt="deltix" src="/predownloaded/9c/ed/9ced30bc043cfa5c6928d46ec78c7c77ac87b0a8.png" style="float:right; height: 150px; "/></a> <p>Hi <span style="font-weight:bold">Code</span><span style="color:rgb(71,94,152);font-weight:bold">forces</span>!</p> We are **[DELTIX](https://deltix.io/)**. Founded in 2005, DELTIX is one of the market leaders in software development for financial research and products for systematic and algorithmic trading. In 2020 DELTIX joined the EPAM family. Our mission is to turn promising ideas into breakthrough products fast. We are experts in: * aggregation, storage, and processing large volumes of time-series data * data modeling * testing and deployment of quantitative models In our team we value skills like: * knowledge of algorithms * high-performance coding * low latency data streams processing [Learn more about DELTIX]( https://deltix.io/) Throughout the year, once per quarter, we will be invi...

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What if tourist goes rainboy mode? (Simulation) DISCLAIMER: NO TOURISTS AND RAINBOYS WERE PINGED Ah yes, two names that most people on Codeforces have heard -- <b>t<span style="color:red;">ourist</span></b> and <b><span style="color:purple;">rainboy</span></b>, one known as the CP Legend, and one as the user who does everything reverse. Such a great idea to put them together &mdash; a hypothetical user with the same ability as <b>t<span style="color:red;">ourist</span></b>, and solves problems the <b><span style="color:purple;">rainboy</span></b> way. _For those unaware of the "rainboy way", it means solving the problems in reverse order. In particular, if he cannot solve the final problem, he solves no problems in the contest._ Unfortunately, <b><span style="color:purple;">rainboy</span></b> had not yet reached red, peaking at 2398 rating. How far can this user go? We shall simulate this user through all the contests that tourist and rainboy took part in comparably, which adds up to 60 contests from [contest:745] to [cont...

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Codeforces Round #801 — EPIC Institute of Technology Round (Div. 2) <a href="https://epic-institute.io/"><img alt="EPIC" src="https://assets.codeforces.com/images/deltix/epic2022.gif" style="float:right; height: 230px; padding-left: 35px; padding-right: 73px; padding-top: 41px; padding-bottom: 33px;"/></a> Hi, Codeforces! We welcome everyone to take part in [contest:1695], which will start on [contest_time:1695]. The round will be rated for participants of Division 2 with a rating lower than 2100. Division 1 participants can participate unofficially in the round. You will be given 5 problems and 2 hours to solve them. One problem will consist of multiple subtasks. The score distribution will be 500 &mdash; 750 &mdash; 1250 &mdash; (1250+1000) &mdash; 3000. The round was prepared by me, [user:ki0apa,2022-06-16], and [user:akifpatel,2022-06-16]. We would like to say a word of appreciation: - to [user:antontrygubO_o,2022-06-16] for amazing coordination of the round - to [user:18o3,2022-06-16], [user:bobbilyking,2022-06-16...

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EPIC Institute of Technology, 2023-2024 Enrollment Campaign <a href="https://epic-institute.io/"><img alt="EPIC" src="https://assets.codeforces.com/images/deltix/2_logo.gif" style="float:right; height: 154px; padding-left: 35px; padding-right: 73px; padding-top: 41px; padding-bottom: 33px;"/></a> Hello, Codeforces! A year ago we talked about our educational project **EPIC Institute of Technology**. Details can be found [here](https://mirror.codeforces.com/blog/entry/102993). Now we are pleased to announce that we are starting the admission campaign for the 2023-2024 academic year! EPIC Institute of Technology is more than just an educational institution; it's a hub of innovative ideas and brilliant minds coming together! Here we make a difference and create a point of rapid growth for talented and driven individuals, leveraging the truly global leadership position of EPAM. EPIC Institute of Technology is committed to establishing and maintaining the highest standards by bringing together bright professionals to share Deltix unique expertis...

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A nice way to think about a really nice problem. Hi, recently I've been trying to do problems that are way too hard for me and stumbled across the following problem from Deltix Summer 2021: [https://mirror.codeforces.com/contest/1556/problem/E](https://mirror.codeforces.com/contest/1556/problem/E). I would recommend people actually go and try the solve the problem first before looking at this post as there will be problem spoilers here. I took the day trying to think of solutions to this problem and I actually made a handful of nice observations but ultimately got stuck at some point and didn't really figure out what to do. After a lot of frustration I eventually decided to look at the editorial, but even after viewing the solution I was still stumped about the intuition behind the answer. I looked on youtube as well and didn't find much of use which led me to some sort of upset state about not being able to understand the problem well. Regardless I kept thinking throughout the day and recently the problem solution has hit me in a very elega...

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Deltix Round, Autumn 2021. Editorial [tutorial:1609A] **Prepared by** [user:vladik,2021-11-28]. **Solution:** [submission:137274527] [tutorial:1609B] **Prepared by** [user:aleXman111,2021-11-28]. **Solution:** [submission:137274647] [tutorial:1609C] **Prepared by** [user:aleXman111,2021-11-28]. **Solution:** [submission:137274769] [tutorial:1609D] **Prepared by** [user:4llower,2021-11-28]. **Solution with** $O(n \cdot log(n))$: [submission:137274837] [tutorial:1609E] **Prepared by** [user:aleXman111,2021-11-28]. **Solution:** [submission:137274954] [tutorial:1609F] [problem:1609G] Let's try to solve the problem without asking for changes. Note that in the matrix constructed in this way for the move from (i, j) it is always profitable to go to the cell with the smallest number. This can be seen more clearly in the matrix of the first test case:  This allows you to solve the problem with complexity $O(n + ...

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Deltix Educational Resource We are excited to announce a new educational resource that is coming soon under the **Deltix** umbrella. Here is a list of paid part-time positions for teachers who want to join our rock star team: - Math & statistics - Algorithms & data structures - Data science - Advanced programming languages - Systems architecture - Networks and clouds - Practical time-series analysis - Machine learning - Security - Real-time backend (architecture) - Operating systems - Product strategy, vision, marketing and innovation Each discipline will include lectures and practical exercises. Some of them will also offer mentorship for the final project. Our resource will not be publicly available. Excited about the opportunity? Complete the form at https://forms.gle/spXr3DaSYmRYePER9 and we will get back to you with further information. Fill free to drop us a line at epic@epam.com if you have any questions.

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Rating change problem for ones who dropped to CM after round 740 and gave round 741 Hello, I'm quite depressed now but I would like to try for the last time.<br> The participants who dropped to CM after round 740 and gave round 741 are **unrated** in round 741 so far. The author of round 741 said that `This round will be rated for the participants with rating lower than 2100`. Clearly, I'm one of them. <br> So I kindly ask [user:MikeMirzayanov,2021-08-28] if there is any issue with the rating system. If it simply cannot be fixed, please make an announcement before Deltix Round on Sunday, because I think that the rating will be very messed up after that round if the fix for round 741 is still pending. Thanks.

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Deltix Round, Summer 2021. Editorial [tutorial:1556A] **Prepared by** [user:aleXman111,2021-05-30]. [tutorial:1556B] **Prepared by** [user:aleXman111,2021-05-30]. [tutorial:1556C] **Prepared by** [user:Vladik,2021-05-30]. [tutorial:1556D] **Prepared by** [user:Vladik,2021-05-30]. [tutorial:1556E] **Prepared by** [user:netman,2021-05-30]. [tutorial:1556F] **Prepared by** [user:netman,2021-05-30]. [tutorial:1556G] **Prepared by** [user:netman,2021-05-30]. [tutorial:1556H] **Prepared by** [user:300iq,2021-05-30]. **P.S.** Editorial for problems **E** and **G** will appear a little later.

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Crazy Code? Yesterday, I took part in Codeforces Deltix Round Spring 2021 [Div.1 + Div.2], and happened something incredible. I solved out the problem D and pasted the pretest(37), but I failed the system test(36). [My original code](https://mirror.codeforces.com/contest/1523/submission/117905874) [Later accepted one](https://mirror.codeforces.com/contest/1523/submission/117952778) The two codes are almost the same. Though my algorithm is to solve the problem randomly, it shouldn't exit a the time of 1.6s. Is there something wrong with my original code, or is there anything else wrong with the platform? Thanks.

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Deltix Round, Spring 2021. Editorial [tutorial:1523A] **Prepared by** [user:Vladik,2021-05-30]. [tutorial:1523B] **Prepared by** [user:aleXman111,2021-05-30]. [tutorial:1523C] **Prepared by** [user:netman,2021-05-30]. [tutorial:1523D] **Prepared by** [user:Vladik,2021-05-30]. [tutorial:1523E] **Prepared by** [user:aleXman111,2021-05-30]. [tutorial:1523F] **Prepared by** [user:netman,2021-05-30]. [tutorial:1523G] **Prepared by** [user:Vladik,2021-05-30]. [tutorial:1523H] **Prepared by** [user:74TrAkToR,2021-05-30].

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An issue about ratings update In the last deltix round I got place 2757 and score 2271 but codeforces says that I got 4320 and score 1184 and +170 should be added but only 104 points are added [user:MikeMirzayanov,2021-11-30] can you please look into this ?

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I need help with problem D in the recent Deltix Round As my title stated, I really need help with understanding D (https://mirror.codeforces.com/contest/2002). (Sorry, I'm really dumb :<<<). So the statement is like this (D1): Given a permutation with some persistent swap queries and a dfs algorithm, check if the permutation after each swap can form a dfs order of some perfect binary tree. I really think that as long as the permutation starts with 1, we can always recreate a perfect binary tree from the permutation. Because like if we assign a pointer p = 0, when we traverse on a binary tree, when we enter a node u, we can just assign p = p + 1, and then assign a[u] = P[p] (P is the original permutation), hence it always exists (Did I misread the statement??). Help me guys I'm really dumb :<<<

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Message from System regarding similar codes and skipped message popping up in DELTIX ROUND(DIV 1+DIV 2) Summer 2021 @MikeMirzayanov I have received the following message from the system. I pasted my code accidentally on ideone and the default settings was set to public in my desktop. I don't know why both of my problems are skipped. Problem A was simple and there was no need of compiler. I used logic and online compiler in B question and the retards giving contest copied my code. I would request you to take back any action on me I would be cautious from next time. Thanks in Advance!!

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