forthright48's blog

By forthright48, history, 3 years ago, In English

Hello everyone,

We invite you to take part in the online replay of Intra NSU Programming Contest, Summer 2018. We arranged the contest for the junior contestants of North South University. The problems are relatively easy, but we hope the set will be interesting for all of you.

Thanks to Labib666, flash_7, nabila_ahmed, prantoran, hasib, Alvee9, Sherlock221B, kimbbakar, aminul, anirudha and DiscoFighter47 for preparing the problem set.

Contest link:
Time: July 27, 2018 at 7:00 PM (GMT + 0600)
Duration: 4 Hours
Contest format: Individual

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By forthright48, history, 6 years ago, In English

Hello Codeforces :)

The third round of HourRank is here and I am glad to be able to welcome you all. The contest will be held on 02:00UTC Wednesday, 2 December 2015. You can sign up for the contest from here.

The contest is rated and top 10 contestants from leaderboard will win HackerRank T-Shirts :D

The contest contains four challenges that are prepared by me (forthright48). I want to thank the HackerRank team and Shafaet, wanbo, svanidz1 and Arterm for testing the tasks.

Contestants will have 1 hour to solve these problems, which I hope is enough, but not more than enough. I hope you will enjoy your hour with Alex, Professor Numerico, Dumdum and Karas.

Best of luck for the contest. See you on leaderboard.

UPD1: Less than 12 hours left. Don't forget to register :).

UPD2: Score distribution: 20 — 40 — 70 — 70.

UPD3: Contest is finished. Editorial is published. Congratulation to winners :

Here are the top 5:

  1. LayCurse
  2. zshi
  3. zerokugi
  4. negativebplusorminus
  5. rnsiehemt

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By forthright48, 6 years ago, In English

Hello Codeforces.

I want to propose a large scale cooperation for writing Editorials for all of Andrew Stankevich Contests. They are amazing contests and it's a real bummer that they don't have editorials. But so what? If all of us contribute to writing editorials for problems that we are able to solve, then it is easily possible to prepare full editorials for all of the contests.

It might have been tough in any other circumstances, but I think with a strong community like Codeforces, this project is easily feasible. So here is what I am proposing:

  1. A blog post will be opened for each of the ASC contest, with title "Andrew Stankevich Contest XYZ Editorial".
  2. In that blog post I will write down the Editorials for the easy problems, so that "Big Guys" don't need to waste their valuable times with trivial problems.
  3. The problems I fail to solve ( and there will be plenty of those ) will be marked "Missing".
  4. Eventually, a kind soul will post a comment with an editorial for missing problem. I will simply link that comment with the corresponding problem.
  5. Eventually people might comment related problems, more resource or better explanations. I will link them too.

Once full editorial for contest i is complete, we will move to i+1. It might take some time to cover all of them, but slowly and eventually we will be able to build something that will come useful to so many programmers :)

Now, how can we make this project better? Do you have any suggestions? I am already working on ASC1. I will be publishing it withing few hours.

Also, is there any way to make a blog post "Community Wiki" or something similar. So that even if I am the one who is posting the blog posts, other people ( perhaps above a certain rating ) are able to edit the posts.


marat.snowbear suggested to use Codeforces groups. Seems like Codeforces Groups is going to suit this project better. A public group has been created ASC Editorial Writers. Those who are interested, they can join the group. All the editorials will be published inside the group so that all the editorials can be found in one place. The blog posts can be edited by Managers, regardless of who created it. Non-managers can contribute by commenting. So it's a fusion of Wiki + Comment.

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By forthright48, 6 years ago, In English

I was trying to solve a problem on HackerRank, Devu and a Journey on Metro.

I wrote a solution using BFS and top-down memoization. Here is my submission: Submission.

When I compared my output with the judge output, I found that I am getting Wrong Answer due to precision error. The 6th decimal place seems to be different on some cases. So I looked into the analysis to see if they had some trick to reduce the precision error. Well, they did the same thing but just bottom up.

Bottom up is faster than top-down. For some cases, we can even save memory using bottom up. But I never heard about bottom-up being more precise.

I changed all double variables into long double later, which got more test cases correct but not all. Submission.

Any idea what is going on? Why is this happening?

UPD1: Got my answer from misof's comment.

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