By Vladik, 3 days ago, translation, In English
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author's solution: 96602393

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author's solution: 96598752

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author's solution: 96727345

P.S. We will add our own solutions soon

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By Golovanov399, 42 hours ago, In English

Sorry for the issues with a couple of problems

Problem A of tc/div2 (Finding Sasuke)
Problem B of tc/div2 (A New Technique)
Problem C of tc/C div2/A div1 (Perform Easily)
Problem D of tc/D div2/B div1 (Shurikens)
Problem E of tc/E div2/C div1 (Solo mid Oracle)
Problem F of tc/D div1 (Roads and Ramen)
Problem E of div1 (A Convex Game)

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By Priyansh31dec, history, 27 hours ago, In English

Elysium brings to you — “ ProSort ”, an online programming competition organized by IIITD’s programming club Foobar.

It is a team event that gives you a chance to go head-on-head with the country’s brightest algorithmic brains and solve a variety of challenging programming problems.

ProSort is a competitive programming contest aimed at college students. You will be required to solve algorithmic puzzles. The contest will be organized on Codeforces and players can form teams of up to 2 members. This will be a great opportunity to showcase your programming skills and also go head-on with the best programmers across the country.

Date 26th October 2020

Timing 6:30 to 8:30 pm

Venue Codeforces

The event will be a part of Elysium’20, IEEE IIIT Delhi’s online tech week.

We have a cash prize of Rs. 6,000 and goodies worth Rs. 72,000 for the top three teams (Both Indian and Non Indian).

Registration link

Contest link The contest starts today at 6:30 PM (IST)

All the best,

Team Elysium

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By Toxic_Codechef_Admin, history, 2 days ago, In English
Why post about Codechef on Codeforces?

I feel that codechef seriously needs to work on people they appoint as admin.

While i believe there have been many nice and skilled codechef admins.

But in recent months, the current admin / Codechef_admin (or the guy behind it) is really pissing most of us off, first of all he’s behind a mask so we don’t actually know who he is, also he/she is short tempered, childish, very unprofessional and immature

Here are some comments.

Who talks from an official handle like that? He/she is very unprofessional, rude and actually proud of his position, he deletes any account he/she want, unlist/flag/close any post he/she want, in other words he/she thinks they own Codechef.

Nowdays, he gets on with keyboard war, giving shet arguments, lame jokes and fighting with users, desperatly trying to prove him right

Sometimes, codechef feels suffocating.

I request any one in high authorities of codechef to at least accept public feedback on people who you appoint as mods.

Personally, I don’t want this admin, i would prefer some one with a calm head and positve vibes, instead of this toxic arrogant person

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By Ravenclaw_OIer, history, 21 hour(s) ago, In English

I think this will be beneficial for people who are preparing for OIs, whether it is CNOI mode (no realtime judge feedback) or IOI mode. Since partial scoring is really different from the current CF contests.

I think maybe Codeforces IOI Round # $$$x$$$ can be held in parallel with the normal Codeforces Rounds.

Apart from that, it would be great to see more kinds of contests.

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By just_for_blogging, history, 36 hours ago, In English

Hi everyone, please don't judge me on basis of rating on my this account. It is my alternative account to freely ask query/doubts related to CP (without fear of downvoting). In every div2 contest I am able to 4 problems normally. I have been doing CP since 6 months on codeforces but I rarely find Algorithms based problems in Div2 contests. First 3 problems are usually greedy/constructive or some observation based. 4th problem is usually on graphs/dp or some logic based. Rest of the problems sometime require algorithms but most the time they are constructive/dp/greedy problems. At max, bfs/dfs and some basic graph algorithms based problems are there. I am not pointing that their is issue with current problems types. These problems really help in problem solving but these kinds of problems fails to test algorithmic skills of participants.

I want to see more algorithmic problems in Div2. If it is not possible to change current problems format in Div2, MikeMirzayanov may can bring up a new contest series whose problems will be more oriented towards algorithmic skills. This thing can help to bring more variations in CF contests and problemset.

I know this issue have been raised few times ago and was rejected by saying that Div1 contains more algorithmic problems and if anyone wants algorithmic problems then he/she should reach div1. But I think it is not justified to keep algorithmic problems to Div1 only. I know it's difficult to make new algorithm based problems for each contest but I think it is needed to bring algorithmic skills into back into CF specially for Div2 contestants. I only want to say that CF is best ever platform which conducts frequent contests (smoothly) without compromising with problems quality but thing is that I thinks CF lacks algorithmic problems for DIV2.

Meanwhile Can anyone recommend me platform which conducts frequent contests which are more algorithm based.

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By fitisovartyom123, history, 2 days ago, In English

As far as I know, the round duration of 2 hours has been a standard since the very beginning of the Codeforces, therefore all the changes to it may appear to be inconvenient for experienced Codeforces users. But the idea of making rounds a bit longer has come to me many times, so I thought I should share my opinion on the topic.

I guess that it is usually true that if a person is not way ahead of his current division, he doesn't have enough time to even read the last 1-2 problems during the round (if we take an average round with 6-7 problems). But those are the hardest and the most interesting problems of the round, so it is sad to skip them. And this is even sadder to understand, that if you have solved your normal amount of problems and have only 20-30 minutes till the end of the round, it is pretty much impossible to come up with the correct solution for at least one of the following problems and implement it. On the other hand, the slight change of giving the additional 30 minutes could have helped the situation and significantly increased chances to submit it. Also, it gives people who are not so successful in "speedforces" a chance to achieve their potential and gain more rating.

P.S. This was intended to be not a complaint on the format of the rounds, but a suggestion for the improvement. Feel free to criticize it. I appreciate all the feedback on the topic.

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By vladcainamisir, history, 23 hours ago, In English

Hello Codeforces!

TLDR: Daily Coding Questions for free

After reading a lot of tutorials on competitive programming, I noticed a recurring piece of advice: practice every day. I tried to do so, but it was rather difficult as there are lots and lots of problems on CF and the thousand more online judges.At some point, when I was talking to my friend about this, we tought about a service which sends you a problem every single day, along with the explanation and the source code in the form of an editorial.

One month later, The Daily Coding Question was born. It's a free service developed by me, ivan.tudor and Mihai.Indreias , and we would be glad if you told us your opinion about it and definately sign up!

Update: Wow guys, thanks a lot for all the support! We weren't expecting this! From tomorrow, you will all receive your daily coding questions!

Update 2: We just hit 100 users! Thanks again and I hope more people will see this! Please share this with your friends as all programmers are welcome!

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By r3novatio, history, 11 hours ago, In English

I came across this problem in which you have been given a directed graph $$$G=(V,E)$$$ with $$$|V|,|E|\leq 10^5$$$ and one additional edge can be added to $$$E$$$. What can be the maximum size of a strongly connected component in the resulting graph?

If anyone knows an approach, do share.

Thanks.

EDIT: I apologize that the $$$O(V.(V+E))$$$ algorithm that I thought would solve this also turned out to be incorrect.

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By arujbansal, 14 hours ago, In English

Hey guys, I made a video on the Convex Hull Trick (a great dynamic programming optimization). I explain the general idea and how we can implement it/the idea behind using it when:
1. Our slopes are monotonic and our query values are monotonic
2. Our slopes are monotonic

I basically explain it through the last problem of the atcoder dp contest (links to everything are available in the video description) so this video also serves as an editorial for Frog 3.
I do recommend that you first read the description as this video does have prerequisites.

Here is the video: Convex Hull Trick Video

You can read more about CHT here: CP-Algorithms Convex Hull Trick and Li Chao Trees

I don't go into dynamic CHT or Li Chao Trees but you can check the video description for a tutorial on Li Chao Trees by radoslav11 which is a great tutorial. I was easily able to learn how Li Chao Trees work from it.

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