Simple, natural statements give more motivation than lengthy, artificial statements. Then in n lines print the moves themselves. standard output. Feel free to copy, contribute and/or comment. output. And people will not have the joy of unfolding the solution, but will write something stupid instead, because of course they will. Hope u don't mind :). Can I ask what does the mask represent? best problemset for beginners and intermediates. EDIT: okay this might be wrong, let me get back. Are you sure you want to create this branch? The input consists of multiple test cases. Virtual participation. Max Flow. Codeforces doesnt allow cloning problems, https://codeforces.com/gym/102961/submission/109356942, https://codeforces.com/gym/102961/submission/109358588, https://codeforces.com/gym/102961/submission/109359183, While I personally dislike the tight TLs on CSES (e.g. Print YES, if the boys can divide the watermelon into two parts, each of them weighing even number of kilos; and NO in the opposite case. Because there were a ton of problems in the Problemset itself for each difficulty level, so I decided to solve only the most solved problems out of each difficulty level, starting from 800. Never use someone else's code, read the tutorials or communicate with other person during a virtual contest. Well, you two certainly achieved that(milked some contribution) lol. Well, ask yourself who's the dumb when they judge someone's comment by their contribution. Virtual contest is a way to take part in past contest, as close as possible to participation on time. Desktop version, switch to mobile version. It's hard to "practice the techniques explained in the books" when the judge is so ridiculously slow that even the most obvious, intended solutions TLE. Yes, made a video with proof for worst case time complexity of the solution: https://youtu.be/lPLhmuWMRag. If there are less than two elements in the set, its cost is equal to 230 2 30. so that one 2^n factor in the time complexity will be just 89(worst case), which is enough to get accepted. Since then, the book has been downloaded over 500,000 times, and many people are already using it to learn competitive programming. The only programming contests Web 2.0 platform, adjacent pairs of cells with different characters, adjacent pair of cells with different characters. And how do we transition? A geometric progression with common ratio k is a sequence of . The point is to make sure you have a well optimized library, so it doesn't hurt you in the future, at least that is my take, especially since in cpp it is plenty of time already in every problem. In one move the king can get to the square that has a common side or a common vertex with the square the king is currently in (generally there are 8 different squares he can move to). I am finding some problems a little difficult to understand like Prefix sum queries. That is actually very important topic for me for the last several month. only one section is accessible in the list it mentioned which is searching and sorting how to access other sections of cses on codeforces?? E. Black and White Tree. In the problems there should be a link to the orginal source. Take the problem NWERC 2017, Problem J as an example. One hot summer day Pete and his friend Billy decided to buy a watermelon. Never use someone else's code, read the tutorials or communicate with other person during a virtual contest. 1 + Div. And I saw many problems where legend was replaced by a formal statement, and it was harder to understand. On problemsetting - Codeforces As if he gonna make some bucks off of it. Problem - 1853C - Codeforces People will abuse it. Hmm perhaps, but heavily optimized Java code fails on CSES, even when it works in under 200ms on Codeforces. After that the watermelon was weighed, and the scales showed w kilos. Moreover, I dont see any mentions of a license on the website, which means it should be by default under exclusive copyright. If you've seen these problems, a virtual contest is not for you - solve these problems in the archive. The only programming contests Web 2.0 platform, $$$\{\cancel 1, 2, \cancel 3, 4, \cancel 5, \cancel 6, \cancel 7, 8, 9, 10, \ldots \}$$$, $$$\{\cancel 2, 4, \cancel 8, 9, \cancel{10}, \cancel{11}, \cancel{12}, 13, 14, 15, \ldots\}$$$, $$$\{\cancel 4, 9, \cancel{13}, 14, \cancel{15}, \cancel{16}, \cancel{17}, 18, 19, 20, \ldots\}$$$. Um_nik: I like when the solution is hidden under multiple layers of reductions, and each reduction needs some A-ha! Server time: Jul/29/2023 12:41:28 (j3). There are two different types of creating a problem: coming up with an interesting statement and solving it from scratch, or working on the problem backward: by researching some construction or creating a problem directly from some idea. The first line contains the number of test cases $$$t$$$ ($$$1 \le t \le 500$$$). I don't have any experience with Python in competitive programming, but I've heard that it's recommended to use PyPy as it's usually much faster than Python. when is it useful to do CSES problems? A's plan is to walk down and then either dash left or right depending on where M happens to be. Why do I need to log in to see statistics? I like problems better, if their statement feels "natural". Idk, we just discussed some ideas with my friend Umqra and then we decided that we have enough decent problems for a div2. Technically, it's not "stealing". There is an increasing number of platforms and olympiads which need more and more problems, and when the demand exceeds the supply, the quality of the problems tends to decline. This repository is dedicated to my Python solutions for CodeForces problems. Why does trying to hack Digit Queries give internal error? There are two main reasons why I decided to do this project. for Java users), I think they must be intentional, not due to a slow judge. https://cses.fi/problemset/task/2137 Can somebody tell me about the solution of this problem? I dont know much about cf but it is in cc. In brief, on the contests held by Codeforces rules you write solutions to the problems that are tested during the contest on a very small number of tests. However, the Codeforces judge is much faster, which solves this issue. As if you precalculate the set of valid mask for each mask. In the fourth test case, a possible way of splitting the set is $$$(2,3)$$$. My submissions are getting TLE on cses. It is supported only ICPC mode for virtual contests. (Since clearly the author knows what judge the problems are on, and set the time limits accordingly. In the second, third and fifth test case, we can prove that there isn't any possible way. These four are sorted in the decreasing order of my preference. The package for this problem was not updated by the problem writer or Codeforces administration after we've upgraded the judging servers. On the occasion of the city's anniversary, a decision was taken to pave the Square with square granite flagstones. Many of you know about the CSES Problem Set, an online collection of over 300 competitive programming problems made by pllk! $$$S$$$ will be changed as follows: The smallest element left after $$$k = 3$$$ days is $$$9$$$. A Solution of the Industrial Nim Game Problem. So basically, you took the CSES Problem Set and removed the Code Submission Evaluation System part. This action results in ending up in the room 1 1, so the answer is 0 0. Finally I came up with an elementary description and made it a problem. Solving problems is much more interesting than reading/learning books/papers. The only programming contests Web 2.0 platform. They could have said, given an array consisting of integers 0-2. It is the thing I always wanted when I started competitive programming, but never had (now I'm old). Time to write something useful (hopefully). 1.1. I made some problems where I wrote legend after creating a problem, and it was harder to understand. I don't think CF has different time limits for different languages. The only difference between the two versions of this problem is the constraint on the maximum number of operations. Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ICPC mode for virtual contests. Each flagstone is of the size aa. L, R, U, D stand respectively for moves left, right, up and down (according to the picture), and 2-letter combinations stand for diagonal moves. Could someone explain problem Two Stacks Sorting? I don't know how other problemsetters do this 2. 4) Divide the tree into components in which you can perform simple Fenwick tree operations, but . For example in math section you can add: number theory, combinatorics, probability, etc. In the sorting and searching section, I utilized the same implementation, Java got TLE but C++ can easily get accepted. Given a graph, output a sequence of checkpoints, so that when you go through checkpoints in a shortest way, you visit vertices as in the array p. It was, more or less, the original statement. It is supported only ICPC mode for virtual contests. rng_58: In most platforms, we have trouble with finding sufficiently many high-quality problems. This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository. Surely it has room for improvements (like everything else in engineering), but did you try to improve the original content instead? Please pllk make the limit $$$2\,Sec$$$ and I guarantee I will never use the Gym instead of $$$CSES$$$ otherwise I am forced even if I don't feel like. How did you get ratio experimentally? I obviously prefer when the code is short and clean, but it is actually not necessary, there are a number of very nice problems which require some tedious data structures, but it is still an important point. Are there any plans on 'hacked' notifications? input. output. Although this approach is easy to use in a wrong way (as coming up with a problem based on a formula you have somehow found in Wikipedia (Count Pairs (CF 572 Div1 B)), when used right, it produces really cool problems. F. A Random Code Problem. Suggestion: require a description of the testset from the setter with intention listed for each test group/generator, statements are not always well written, and especially translated. $$$^\dagger$$$ An adjacent pair of cells with different characters is a pair of cells $$$(r_1, c_1)$$$ and $$$(r_2, c_2)$$$ ($$$1 \le r_1, r_2 \le 2$$$, $$$1 \le c_1, c_2 \le n$$$) such that $$$|r_1 - r_2| + |c_1 - c_2| = 1$$$ and the characters in $$$(r_1, c_1)$$$ and $$$(r_2, c_2)$$$ are different. Imagine that you would write 300 page book about most known CP problems/algorithms/data structures. The problem statement has recently been changed. It got AC now. I'd like to use this chance to comment on the stupid TL again. There are two main reasons why I decided to do this project. Never use someone else's code, read the tutorials or communicate with other person during a virtual contest. Many people (often including myself) think that you HAVE to have at least one graph problem or at least one data structure problem in a contest and these "mandatory" problems are always very bad and uninspiring. You can print each letter in any case. The king is left alone on the chessboard. I don't have a lot of problemsetting experience yet, but I still would like to write some own thoughts on problemsetting at the end of this post. Maybe so, but at least (I hope) they add something new to this website and offer explanations for people who didn't solve those problems in-contest. Each problem consists of it's hashtag, so that you can easily search it in Codeforces. How to sort problems by difficulty level? Petr Mitrichev, Last 3 Days in Sao Paulo Training Camp 2010. If you find any of the solutions useful, don't forget to star this repository. Determine if you can split it into exactly $$$n$$$ pairs (i.e. each element should be in exactly one pair) so that the sum of the two elements in each pair is odd (i.e. when divided by $$$2$$$, the remainder is $$$1$$$). Codeforces Practice Tracker Browser Extension, Educational Codeforces Round 152 Editorial, Educational Codeforces Round 152 [Rated for Div. Each CSES category will be its own separate gym contest, listed below. Damn, speaking from experience aka -82 contribution, I thought that it was cool to have such low contribution lmao. Let's call integer martian if it is a non-negative integer and strictly less than 2k 2 k, for example, when k = 12 k = 12, the numbers 51 51, 1960 1960, 0 0 are martian, and the numbers , 1 1, 218 21 8, 4096 4096 are not. Next time try to think for more than 2 seconds before commenting, kthx. The CSES Judge is very slow, often resulting in correct solutions that should get accepted instead getting the TLE verdict. Problem - 1849F - Codeforces Codeforces. It is like a well-crafted artisan piece; like expensive icecream. How do I set my home country on Codeforces? Rather than using TreeSet, which is the technique taught in the book, you're forced to process queries backwards and maintain a left/right[i] which is the closest index to the left/right of i which isn't removed yet with a path compression like thing. Here is the list of blogs, connected to this topic that I managed to find: Blog by Sammarize on the entire problemsetting process. standard input. 256 megabytes. And unrelated, I completely agree with TheeLooser, even if it is within license to take the whole problem set and put them here it does not feel right. The first line contains a single integer $$$n$$$ ($$$1 \le n \le 20$$$) the length of the array. It is supported only ICPC mode for virtual contests. Thank you for your submissions and new test cases through hacking! Server time: Jul/27/2023 20:48:23 (j3). Moreover, I think that this way of creating problems is somewhat underrated, and is one of my favorite ways. I am missing a proper defintion on how to count distinct towers. Endagorion: take a topic/algorithm and think of a way it could work in an unexpected setting (this includes combining seemingly unrelated topics), just think of an original problem and see if it's at all solvable, make it more general/constrained if needed. It is hard to say, it is more about feeling that problem was beautiful than saying "this problem fulfill the checklist". For Problem-X (Sum of Three Values), my submission on CF https://codeforces.com/gym/102961/submission/109356942 got TLE on Test-10 but the same code got AC on CSES after passing all 23 tests there, when the TL was 1 second there (whereas the TL on CF for this problem is 2 seconds). The description of the test cases follows. I regard competitive programming as "discrete math puzzle solving contest" rather than "programming". I think that inexperienced problemsetters often use this way and miss easier solution when the problem is finalized, just because they "wanted to create a problem with this particular solution". rng_58: Among AtCoder frequent writers sugim48, maroonrk, DEGwer. ), especially written in English. For the second test case, BABB is one possible answer. I can see why people think it's fine to have a uniform TL, since you can think of languages as tools, and you choose the one you like as a key which unlocks the problem's door. Example: 1204C - Anna, Svyatoslav and Maps here it was possible to write. Today we have released a new version of the CSES Problem Set: CSES Problem Set is a collection of algorithmic programming problems that can be used to practice competitive programming. The description of the test cases follows. If you've seen these problems, a virtual contest is not for you - solve these problems in the archive. This way we can make thinking-oriented and natural problems. It simply leaves us all by ourselves to find the solution which is what CP is all about. Never use someone else's code, read the tutorials or communicate with other person during a virtual contest. Operation -- decreases the value of variable x by 1. when the judge is so ridiculously slow that even the most obvious, intended solutions TLE. So, advice: If you want to set a contest that people would really like, keep modifying your problemset until you like every problem in it, no matter how long will it take. Being good in math helps because then you understand how to prove lemmas correctly. Every day, he will remove the $$$a_1$$$-th, $$$a_2$$$-th, $$$\ldots$$$, $$$a_n$$$-th smallest numbers in $$$S$$$ simultaneously. The first line contains an integer $$$t$$$ ($$$1\leq t\leq 100$$$) the number of test cases. When I want to create a problem but am stuck on a certain idea, or am just running out of ideas, it really helps me to just open some random old contest and to read a few problem statements. Problemset - Codeforces You may also add more, newer, problems from each difficulty level folder, present in Problemset Archive of Codeforces, as well. Why not every problem is cloned? 1 -14 2 -10 6 -5 10 -13 10 7 -14 19 -5 19 1 18 -16 -7 12 8, -15 -17 -13 8 14 -13 10 -4 11 -4 -16 -6 15 -4 -2 7 -9 5 -5 17, The only programming contests Web 2.0 platform. I dont understand. Can't we see the solution submitted by other people in gym contests? I feel that could have been a sensible first step. Um_nik: I want to share the beauty of these A-ha! Which sections? If you just want to solve some problem from a contest, a virtual contest is not for you - solve this problem in the archive. Pete and Billy are great fans of even numbers, that's why they want to divide the watermelon in such a way that each of the two parts weighs even number of kilos, at the same time it is not obligatory that the parts are equal. More Nim Game Problems. Dynamic Programming Type. Guide to Competitive Programming and CSES Problem Set However, personally I find this topic really important for the Competitive Programming community. I copied the content of "Nested Ranges count" to chatGPT. There are a total of $$$5$$$ pairs, which satisfies $$$k$$$. This Repo contains the solution for some of the most solved problems of the Problemset of Codeforces. Petya was quite disappointed with his gift, because he dreamed of correct bracket sequence, yet he told his friends nothing about his dreams and decided to fix present himself. Review the problem statement from Codeforces (link will open a new tab). Problem - 567C - Codeforces When I was preparing my contests, I felt that the materials on problemsetting and coming up with good problems would really make the life easier. The grid below is the result of filling in BABB as the second row. So even if you hide topics, they become obvious when you read problems. It is a free Online judges problems solution list. Endagorion: Martian Colony: the first problem I set and was really happy with, Infinite binary embedding (Petrozavodsk 2015, Mikhail Tikhomirov contest 1): a good example how thinking and tinkering with a problem a lot can yield something really good, Addition without carry (ROI 2018): this came to be from solving a somewhat original problem, coming up with a really beautiful solution which was too hard for most contests, and leaving the most interesting subtask. Next time try to think rational for more than 2 seconds before commenting, kthx. I just wanted to say my opinion. I think it would be great if there are discuss section like leetcode. All others are just "implement classical algorithm". Also, if you want to search for the editorial for a particular question, then on the question page you may scroll down and see a "Tutorials" t. Make the array non-decreasing (i.e., $$$a_i \leq a_{i+1}$$$ for $$$1 \leq i \leq n-1$$$) in at most $$$31$$$ operations. The Dynamics of Subsets and routes in graphs. Briefly, these are: problem solution and solution problem. E.g. UPD1: I would recommend reading the second part of "Creating problems" by voidmax. I guess, the term is CPM -- contest per month. ). Each move is described with one of the 8: L, R, U, D, LU, LD, RU or RD. It looks like I'm late to the party. Problem - 1852D - Codeforces Knowledge and preparation of known advanced algorithms (i.e. Codeforces. Determine if you can split it into exactly n n pairs (i. e. each element should be in exactly one pair) so that the sum of the two elements in . One more opinion on what makes a good problem: Contest tasks say a lot about the quality of a programming competition. The fact that their problems are good makes their problems good xd. Given the array a a, Ntarsis wants you to construct some imbalanced array. This is an AP with a difference d = 3 d = 3. The description of the test cases follows. I think that problemsetters on CF are required to spend a lot more time on statements than it is really needed because of low math-culture of participants. how are you going to keep track of the new test cases that are going to be added on cses from hacking? ask them what do they think on this situation: an author likes their problem but they expects participants would dislike it. 1829F - Forever Winter - CodeForces Solution. They produce few but very hard and interesting problems. On the other side, there are many participants who don't like "mathforces" though math is a vast area with lots of different topics (for example, adamant's contest in last Ptz camp is kinda math-y towards the end, but it is not like the problems are all the same). standard output. :(((, see https://cses.fi/book/book.pdf#page=111, https://cses.fi/problemset/task/2138 Please help me with this problems :((( i can't use dp in this dag. Is there any way to hide problem "tags" like DP, Graphs, etc? Firstly, thank you for the helpful initiative! "There are only two hard things in computer science: cache invalidation and naming things.". Endagorion: As I mentioned, the first approach is harder, but generally leads to more interesting problems. mr. Daniil: author likes their problem but expects participants would dislike it. Helps with improving as a contestant too. But before that I would say that he was my favorite. Problem - 1214C - Codeforces The only programming contests Web 2.0 platform. Instead the NWERC authors put it in a nice setting, which makes it a lot more fun to solve (at least for me). I have decided to clone all the CSES problems onto Codeforces! Is it possible to solve this problem with a bitset? - Codeforces Make it like one stop Platform where any beginner can blindly follow. Why aren't the links other than searching and sorting not working? I would disagree. It's just educational and it's said in the license, you're free to redistribute. Please make the change if possible. The only thing that stopped me from solving CSES is that you know if the problem will be DP or Graphs or Math in advance, thus making it less interesting. 3) Merge the two bitsets from steps 1 and 2, creating in this way something very similar to a Fenwick tree, as you can see. 2), Codeforces Round 887 (Div 1, Div 2) Tutorial, Teams going to ICPC WF 2022 (Egypt 2023) WIP List. Endagorion: At around 16 (>10 years ago) for summer camp and local high school competitions. It's a judge which "contains a collection of problems which can be used to practice the techniques explained in the books" (source). Call an array b b of n n integers imbalanced if it satisfies the following: for each 1 i n 1 i n, there are exactly ai a i indices j j ( 1 j n 1 j n) such that bi +bj > 0 b i + b j > 0, where i i and j j are not necessarily distinct. Range 4 contains range 3, and no other ranges. I don't care about the license; I wouldn't do it out of respect. They rushed home, dying of thirst, and decided to divide the berry, however they faced a hard problem. till then here is a sub optimal way to solve the problem: dp[i][mask] = number of ways to fill the cols from ith to mth given that cells of the ith col represented by mask are already filled. CSES problemset is just perfect, no tags, no editorials. Didn't see any nice problems requiring link-cut tree or weighted matching in general graph yet. There will at most 89 valid mask per normal mask and even less. CSES Problem Set is a collection of algorithmic programming problems that can be used to practice competitive programming. The second query asks whether starting from room number a = 2 a = 2, and using the teleporters 5 5 times . Great. Virtual contest is a way to take part in past contest, as close as possible to participation on time. There are both easy and difficult new problems, and some of them cover advanced topics, such as treaps, suffix structures, and FFT. The first line should contain an integer $$$k$$$ ($$$0 \le k \le 31$$$) the number of operations. Also, there are two operations: Operation ++ increases the value of variable x by 1. I just wanted to enquire as to if the book contains an explanation for these topics as well. We would like to show you a description here but the site won't allow us. Problemset - Codeforces Many of you know about the CSES Problem Set, an online collection of over 300 competitive programming problems made by pllk! For the second case, each day the $$$1$$$-st, $$$3$$$-rd, $$$5$$$-th, $$$6$$$-th and $$$7$$$-th smallest elements need to be removed from $$$S$$$. Consider having two stacks. It is guaranteed that the sum of $$$n$$$ over all test cases does not exceed $$$2 \cdot 10^5$$$. Did you have to enter many train cars and count? dfs and similar graphs math. I think this is why the interviewees agree that the approach problem->solution instead of solution->problem results in more beautiful problems. The following line contains string $$$s$$$ of $$$n$$$ characters ($$$s_i$$$ is either A or B) Miriany's top row of the matchstick. https://codeforces.com/gym/102961/submission/109359183. Codeforces. We have now added 100 new problems, and the total number of problems is 300. The only programming contests Web 2.0 platform, 2022-2023 Southern And Volga Russian Regional - Editorial, Editorial of Codeforces Round 889 (Div. There are over 300 problems on CSES, and it will likely take me months to get them all on Codeforces. standard input. C. Monsters And Spells. Problem - 1854D - Codeforces Desktop version, switch to mobile version. The first query asks whether starting from room number a = 3 a = 3, and using the teleporters 5 5 times, one ends up in one of the two rooms S = {2, 3} S = { 2, 3 }. moments needed to find the solution with the people. The first (and the only) input line contains integer number w (1w100) the weight of the watermelon bought by the boys. The problem statement has recently been changed. This Repo contains the solution for some of the most solved problems of the Problemset of Codeforces. The first line of the output gives the number of ranges that each range contains, in the order they were given in the input. Endagorion: as misof puts it, "the less it looks like anything I've seen before, the better". Minimize diameter of tree by applying almost k.operations. Honestly, "please increase TL since my solution is getting TLE verdict" is one of the most stupid request you can ask on competitive programming.

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