Hello Codeforces!!!
We are excited to invite you to IIIT Lucknow’s annual team coding event CODUO, which will be organised in two ladders, one is prelims to be held on Codechef 14th April from 8:30 pm IST and the qualified teams will be invited to participate in the finals that will take place during the period of our annual techfest Equinox. Coduo will be a 3-hour contest ( individual participation or Team of 2 members).
Problem set has 8-9 problems of varying difficulty.
Contest link- https://www.codechef.com/CDUO2021
This contest is a part of our annual technical fest — Equinox`21, IIIT Lucknow.
Thanks to notapig, MR_POssiBLE, lemme_sleeeep, Zankanotachi, skywalker_, ishan_sharma,_darkslayer and Retarded_Ape for contributing several important problem ideas.
Thanks to Induber, Chrollo_Lucifer, agrawal117 and PointBlank for testing our problem set, and providing very valuable feedback to improve problem statements, sample cases, and tests
-And, Thanks to the Codechef team for providing their valuable platform.
PRIZES:
The total prize money (for Winners of Finals) is worth INR 20,000.
Also, the top 3 teams in the Prelims will get 250 Codechef laddus each. We hope that you'll enjoy the contest just as much as we did preparing it!
Good luck!!
Update:Test case was later update for the question Time Table. We will decide the winners considering this factor. We will manually check all the submission for that problem and run it locally to check for their 1st correct submission and for every team the time will be their first correct submission and penalties for the submissions prior to it. Again I am really sorry for this issue :/
We will finalize the winners after considering submissions for "Time Table" as mentioned and then we will update the blogs on both Codeforces and Codechef and the winners will be mailed as well by 5:00 pm IST tomorrow.
Looking forward to a great round. Best of luck to all the contestants and also the setters!!
Looks fascinating to me, really excited for the round!
I wanted to know that whether you guys will publish an Editorial after the contest(Because it's helpful in upsolving)? That's just my personal criteria for participating in this contest, that's why I want to know this.
Yes , we will publish the editorial
Is this for beginners too
yes surely
Is this contest rated?
It's a team contest, so its not rated. But we have another contest lined up for our Techfest and that will be rated :).
Team registration link is expired.
Fixed, now you can register.
Till when is registration open?
Till 11:30 pm today(i.e till the contest ends)
I hope that everyone likes the problemset!! Goodluck everyone!
PS: Contest starts in 8 hours from now
I am a beginner will the problemset also contains some easy questions too
YES!!!!
thanks , the contest was great questions are good
How to register as an individual participant?
Go to the registration form, you just need to ignore the details of the second team member.
Cant both the particpants of the same team login using same login id and password
No you need to login from your default ID usernames. You both can open the contest from you default IDs at the same time.
Please reply to the question written in the comment section of sarkari karyalaya
Done
.
Contest is still going on :/ the time was extended by 30 mins.
Was the intended solution to Social Media Influencer max flow + binary search?
Yes that was indeed the intended solution but unfortunately I messed up a bit while making the tests so some greedy solutions also god accepted. Sorry for that :/
What's the solution for EAZYE??
The trick here was to convert the polynomial into a basis which can deal with Arithmetic progressions easily,the basis in question is langrange basis,please have a look at my notes for a quick explaination- https://documentcloud.adobe.com/link/track?uri=urn:aaid:scds:US:23d7f360-db81-449f-a09d-6586b53d4100
Retarded_Ape
May we get the editorial of the contest? The problem set of the contest was so nice to me. BTW, Thanks to the setter of the contest.
Sarkari Karyalay In this problem am I correct that time complexity will be O(T((n+m)log(n+m)+k^p)), if I use a brute force solution. Was it an intended solution? thanks.
Yess , brute force will pass.
I wasn't sure that brute force will pass, so instead of $$$O(k^p)$$$ I did $$$O(p^3 \cdot k)$$$ in last part of algorithm. That can be done with Hungarian algorithm for assignent problem.
How to solve LUCKY STRING?
Is there an editorial?
I believe it is some DP, can someone explain the solution?
Check out: Link
I haven't had enough time to implement it fully, but i can explain my solution.
Firstly, let's notice that for subsequence we only have to know the longest suffix that is prefix of some string in Kingdom. (It's easy to proof, try yourself) Let's call it describing suffix.
Secondly, number of different describing suffixes is $$$O$$$(sum of lengths).
For each prefix P and each next character C from alphabet, let's precalc describing suffix for P + C. That can be done with Aho-Corasick algo.
Now we have easy dp[L][P] — maximal length of subsequence if we consider first L characters from lucky string and decribing suffix — P.
Total complexity: $$$O((S + A) \cdot Q)$$$, where Q — sum of length of strings in Kingdom, A — size of alphabet.
when will be the editorial published ?
There was an error in a testcase of EZYE because of Integer Overflow,I am terribly sorry for not realizing this while testing the problem,I have fixed that testcase and all solutions have been rejudged.Thanks to sg0071729 and physics0523 for asking me to review the test cases.I really hope that you all can forgive me and I will make sure that this does not happen in the Finals.
I'm unable to enter the finals at hackerearth, Is it happening with others too?
Yep, same for me. I'm clicking the "Start Now" button, and it seems to simply refresh the page without letting me view the problems. Is that the issue you're having?
yeah same thing is also happening with us too
Same
The number of participants keeps on increasing though. Has anyone been able to enter the finals?
My teammate was able to enter
Any updates ?
try loading the link/leaderboard it worked for me
Thanks!
Retarded_Ape Hey, Can you once recheck the testcases of problem "time table" in CoDuo Finals??
Tests for "Time Table" seem to have lectures reserved for the same day and hour, while in the statement it is said that they go without repetition (we've checked it with assert in our solution).
Test case was later updated for this question. Kindly submit your code again. We strictly appologise for the inconveniece caused. We will decide the winners considering this factor in the leaderboard. Don't worry about your submissions in this problem. We will ensure it manually. Again we are really sorry for this issue.
lemme_sleeeep Hey, Can you tell when will you give us the final rank?
Till tomorrow 5:00 pm IST
Now, consider a guy solving his first problem as "TimeTable" and honestly this was the 3rd problem which i looked for and tried it for 30 minutes (although my first submission was AC) and it broke the whole flow for the upcoming problems due to which i did a lot of wrong submissions.
Yea I agree with you totally and I know this must've happened with some of the participants and I am really sorry for that T-T.
When and how will we know the final ranks?
I will manually check all the submissions for that problem and run it locally to check for their 1st correct submission and for every team the time will be their first correct submission and penalties for the submissions prior to it. Again I am really sorry for this issue :/
We will finalise the winners after considering submissions for "Time Table" as mentioned and then we will give the update on the blogs of both Codeforces and Codechef and the winners will be mailed as well.
Please adjust the time penalty for teams who were not able to start the contest on time.
The problem statement of Just do it is unclear. No I/O format has been specified. Please update it.
Why Just do it is added at the end moment. That too with non-understandable statement. Can you just clarify or remove it? Edit: It's removed.
such a shitty contest!
Is it the finals!!!
I found the problems of the prelims much better and interesting than that of finals.
+1, these problems were just too obvious.