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
- Contest Link — https://codedrills.io/contests/amrita-icpc-practice-session-5
- Date & Time — 28 Mar 2021, Sunday, 20:00 IST
- Duration — 2.5 Hours
- Will follow standard ICPC scoring system (20 minutes penalty and 1 point per problem)
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.
- Admin: Vichitr Vichitr Gandas
- Problem Setters: Jatin rivalq Garg, Chaithanya Dragonado Shyam, Vaibhav xennygrimmato Tulsyan and Vichitr Vichitr Gandas
- Aswin aswinashok44 Ashok and Mayank katana_handler Pugalia for the help in round testing.
- Balajiganpathi Balajiganapathi S, Divyansh failed_coder Verma and Ashish Ashishgup Gupta for suggestions and improvements.
Finally I would like to congratulate all the winners:
- rdopti: Rahul amnesiac_dusk Dugar
- Back Again: Raja raja1999 Vardhan, Tejavardhan teja349 Reddy
- NITT 1: Aditya kumaraditya1999 Kumar, Vivek Raveendran, Sudharsan Srikanth
- Return0: Arihant K R, Himanshu HimanshuG Garg, Anay AwakeAnay Karnik
- Invariant: Abhishek darklight13 Chopra, Ravi Kishan, Snigdh Sixpathsguy Sinha
- god_in_my_team: Debajyoti little_angel Dasgupta, Naman namanjain0501 Jain, Praagy frost_ Rastogi
- Squirtle Squad: Arsh Nightmare05 Mahajan, Chandan Kumar, Shubhankar Amitabh
- Codechef hi badiya tha: Lavish Gupta, Rishabh far_from_NOOB Gupta, Utkarsh Gupta
- itna-naam-bhi-nahi-karna: Abhishek AK.... Kumar, Kshitij Parwani, Smit Lunagariya
- Evil Geniuses: Vineet Kumar Dhandharia, Kaustubh Miglani, Pranav Sanjay Maral
- BForBruteForce: Anubhab Das, Arka Choudhuri, Deepamoy Yomapeed Pal
- gib money: Alok Kumar Singh, Diptarag Ray GoatTamer Chaudhuri, Shubham Pandey
- no_ones: Abhishek Jha, Aman Singh
- concon: Carlos cjoa Joa
- 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.
Has the registration for Preliminary Online Round started as the website mentions that we can register between 1 March and 30 April ?
Yes, it has been started from Mar 1st. Register here.
What about the preliminary online round of other region?
Hey, we have no information about other regionals. I don't see any update on ICPC site as well.
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?
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.
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.
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.
There was a typo in start time! (Corrected now). Contest starts at 20:00 IST.
In the original ICPC also, will there be exactly 5 questions?
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.
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.
Thank You!
Thanks.
Reminder to register your team! Contest starts in about an hour.
Why is the Codedrills website not opening on Safari(displaying black page) but working perfectly fine when open on Chrome ?? @Vichitr
Oh man! Safari is a pain. Not sure about the issue! Anyways our site is best configured for Chrome.
lost_martian We fixed this issue, now CodeDrills should work on safari too.
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.
How to solve beautiful permutations?
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.
How to solve Tree Parenthesis ? Is there any editorial for the contest ?
You can find the high-level solution idea in the Editorial tab here.
In que 3 "Beauty of the Tree" acc. to me we need to calculate
|f(T1) - f(T2)|wheref(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 sectionIt 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 :)
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.
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 :)
Multiplicative inverse of a number $$$a$$$ modulo $$$m$$$ is $$$a^{m-2}$$$ mod $$$m$$$ if $$$m$$$ is a prime. Read here.
Thank you
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.
Is it only with me and my teammates or competitive companion is unable to parse questions currently?
Looks like they don't support CodeDrills parsing yet. I have opened an issue with them to add the same.
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.
Thank you!