Vichitr's blog

By Vichitr, 3 months ago, In English

Hello Codeforces,
ICPC Amritapuri Regional will be hosting next team practice round on CodeDrills on Sunday, 28th March 2021. There will be 5 problems to be solved in 2.5 hours.

Contest Details

Registration

  • You will need to create a team on the contest page in order to participate.
  • Team size can be upto 3.
  • While creating the team, add the registered emails of other users to invite them to join your team. They will get an invite email, ask them to accept.
  • For more details on team registration, refer this guide.

Note: Register your teams & accept invites before the start of the contest. This won't be allowed after contest starts!

Prizes

  • Cash prizes of INR 35000 for top 15 teams.
  • 1st Place — INR 5000
  • 2nd, 3rd Places — INR 4000 each
  • 4th, 5th, 6th Places — INR 3000 each
  • 7th, 8th, 9th, 10th Places — INR 2000 each
  • 11th, 12th, 13th, 14th, 15th Places — INR 1000 each
  • Only Indian participants are eligible for prizes but everyone can participate.
  • Prize money is per team.

I hope you will enjoy solving the problems. Any feedback is appreciated after the contest.

Good Luck & Have Fun!
Hope to see you participating!!

UPD: Thanks for participating! Editorials are out!!! All submissions have been made public.

I would like to thank everyone who helped in the round preparation.

Finally I would like to congratulate all the winners:

  1. rdopti: Rahul amnesiac_dusk Dugar
  2. Back Again: Raja raja1999 Vardhan, Tejavardhan teja349 Reddy
  3. NITT 1: Aditya kumaraditya1999 Kumar, Vivek Raveendran, Sudharsan Srikanth
  4. Return0: Arihant K R, Himanshu HimanshuG Garg, Anay AwakeAnay Karnik
  5. Invariant: Abhishek darklight13 Chopra, Ravi Kishan, Snigdh Sixpathsguy Sinha
  6. god_in_my_team: Debajyoti little_angel Dasgupta, Naman namanjain0501 Jain, Praagy frost_ Rastogi
  7. Squirtle Squad: Arsh Nightmare05 Mahajan, Chandan Kumar, Shubhankar Amitabh
  8. Codechef hi badiya tha: Lavish Gupta, Rishabh NOOBxCODER Gupta, Utkarsh Gupta
  9. itna-naam-bhi-nahi-karna: Abhishek AK.... Kumar, Kshitij Parwani, Smit Lunagariya
  10. Evil Geniuses: Vineet Kumar Dhandharia, Kaustubh Miglani, Pranav Sanjay Maral
  11. BForBruteForce: Anubhab Das, Arka Choudhuri, Deepamoy Yomapeed Pal
  12. gib money: Alok Kumar Singh, Diptarag Ray drayc Chaudhuri, Shubham Pandey
  13. no_ones: Abhishek Jha, Aman Singh
  14. concon: Carlos cjoa Joa
  15. Venom: Nikhil Believe Choudhary, Shivang ZiXeL Bhawsar

The winners list is not final. Plagiarism check will be done later! Also non-Indian teams wont be eligible for prizes.

 
 
 
 
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3 months ago, # |
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Has the registration for Preliminary Online Round started as the website mentions that we can register between 1 March and 30 April ?

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    3 months ago, # ^ |
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    Yes, it has been started from Mar 1st. Register here.

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      3 months ago, # ^ |
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      What about the preliminary online round of other region?

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        3 months ago, # ^ |
          Vote: I like it +5 Vote: I do not like it

        Hey, we have no information about other regionals. I don't see any update on ICPC site as well.

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          3 months ago, # ^ |
            Vote: I like it +8 Vote: I do not like it

          Sorry if you're not the person to ask this, but does the rule of "a team may only participate in two regionals" apply this year as well? Is there anywhere I can see the entire list of rules for this season?

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            3 months ago, # ^ |
              Vote: I like it +36 Vote: I do not like it

            Hi Lain, yes you can participate in two regionals like previous years.

            The coming online round won't be a common round however. The common online round was started in recent years to make it easy for contestants, before that (e.g. during the time I participated), each regionals held their own online rounds. Since this time only Amritapuri has announced regionals so far, their online round is separate. If other regionals announce dates, they may hold their own online qualification rounds.

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3 months ago, # |
  Vote: I like it -41 Vote: I do not like it

The logo here says that regionals will be conducted in online mode but on https://www.amrita.edu/icpc21 website it shows regionals will be conducted offline if possible. Is it confirmed yet??

Also just putting it out there, everyone would highly appreciate it if regionals would be conducted in offline mode only.

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    3 months ago, # ^ |
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    The reason is that we are not sure. Recently COVID cases are increasing in India. Many places might have strict guidelines to follow. So this would depend on the situation.

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3 months ago, # |
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There was a typo in start time! (Corrected now). Contest starts at 20:00 IST.

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3 months ago, # |
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In the original ICPC also, will there be exactly 5 questions?

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3 months ago, # |
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There is a problem with creation of team at Codedrills.
When I create a new team for participating in the contest and invite my teammates, they are unable to accept the invite as they are said that they are already in a team.

We three had already participated in a contest before by creating a team for THAT contest.
But we are unable to form a team for this contest again.
Please have a look at it.

Image
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    3 months ago, # ^ |
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    Hi vishaaaal, thanks for reporting the issue. The accept was working and being marked in the backend but the state was not updating in the frontend. We have fixed the issue now and the state should reflect in frontend too.

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3 months ago, # |
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Reminder to register your team! Contest starts in about an hour.

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    3 months ago, # ^ |
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    Why is the Codedrills website not opening on Safari(displaying black page) but working perfectly fine when open on Chrome ?? @Vichitr

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      3 months ago, # ^ |
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      Oh man! Safari is a pain. Not sure about the issue! Anyways our site is best configured for Chrome.

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      3 months ago, # ^ |
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      Hi, the site is well tested on chromium based browsers. But we have not throroughly tested on other browsers. We plan to do that over the next month.

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      2 months ago, # ^ |
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      naitramtsol_lostmartian We fixed this issue, now CodeDrills should work on safari too.

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3 months ago, # |
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I dont know the queue time is too long and sometimes the queue just stops when I am refreshing the page and I am sure my internet connection is fine.

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3 months ago, # |
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How to solve beautiful permutations?

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    3 months ago, # ^ |
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    You can find number of connected components (dfs), then the problem is use to join these connected components using swaps(edges). This becomes a MST problem. Now there can be n^2 edges, but you can optimize by sorting the costs, now pick adjacent costs which belong to different connected components as edges. Then run your favourite MST algorithm.

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3 months ago, # |
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How to solve Tree Parenthesis ? Is there any editorial for the contest ?

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3 months ago, # |
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In que 3 "Beauty of the Tree" acc. to me we need to calculate |f(T1) - f(T2)| where f(T) = max({b[1], b[2], ..., b[k-1], b[k]}) or in simple language we just need to break the tree in two parts and find | max value of tree one - max value of tree two | so what is the use of this line which is written in output section It can be proved that the answer can be expressed as a fraction P/Q, where P and Q are co-prime integers, you should compute P * Q^{−1} modulo 10^9+7, where Q^{−1} is the multiplicative inverse of Q modulo 10^9+7.

Thanks in advance for helping me :)

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    3 months ago, # ^ |
    Rev. 2   Vote: I like it +16 Vote: I do not like it

    They have asked the expected value of the function. It is the average of the answer over all the ways you can break the tree into two parts. The expected value need not be an integer.

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      3 months ago, # ^ |
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      thanks VivekUchiha now it is clear :) but i have a silly doubt :\ what should we the ans of (1/5)Mod M (1e9+7) ...i means how to calculate this ? thanks :)

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        3 months ago, # ^ |
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        Multiplicative inverse of a number $$$a$$$ modulo $$$m$$$ is $$$a^{m-2}$$$ mod $$$m$$$ if $$$m$$$ is a prime. Read here.

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    3 months ago, # ^ |
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    Hey I think you didn't read the problem properly. It asks for expected value of $$$|f(T1) - f(T2)|$$$ modulo $$$10^9 + 7$$$ If you need help in solution, have a look at the editorial.

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3 months ago, # |
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Is it only with me and my teammates or competitive companion is unable to parse questions currently?

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    3 months ago, # ^ |
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    Looks like they don't support CodeDrills parsing yet. I have opened an issue with them to add the same.

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    3 months ago, # ^ |
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    I just added a problem parser for CodeDrills and released it in version 2.22.0, it should work after your browser auto-updates the extension.