Feedback for Encoding OCT 19

nuttela · October 30, 2019, 4:44pm

Our Codechef Campus Chapter Team (Netaji Subhash Engineering College) has been hosting Encoding for over a year and we do it almost every month in Codechef. We try to keep the questions balanced such that from newbies to pros , everyone find it educational.

We would really like to here from the community.
Any feedback is accepted. We will try to improve as well.

Link - https://tiny.cc/enoc2019
For updates, you can follow us at : here

raunaqroxx · October 30, 2019, 4:59pm

This is regarding the question GVR, can anyone explain me, CodeChef: Practical coding for everyone
How this solution got accepted under the constraints mentioned in the question?

pritishn · October 30, 2019, 5:05pm

Have a look at this solution bro.

dshahid3801 · October 30, 2019, 5:12pm

This is because of very less no of primes were present in test case with higher value. This is the reason that many of you got AC even with O(NSqrt(N)), but it appears nearly equal to O(N). The perfect solution for this problem will be Miller Rabin Primality Test for checking prime, then its complexity in that case will be O(N*(lnN)^2)

raunaqroxx · October 30, 2019, 5:15pm

Wow, and I thought O(n*sqrt(n)) was the worst thing

raunaqroxx · October 30, 2019, 5:17pm

Thank you for clarifying, but I wanted to stress upon the fact that the test cases are pretty weak, since these kinds of solutions are getting ACed.

harish_49 · October 30, 2019, 5:18pm

What the heckk!! Did that solution passed

raunaqroxx · October 30, 2019, 5:24pm

Yup. It did. I was going through the accepted solutions to know how to solve this when I encountered this.

aryaman_arora · October 30, 2019, 5:27pm

Why did my submission with fast IO give WA but same solution with cin cout give AC.
https://www.codechef.com/viewsolution/27627411 WA Solution
https://www.codechef.com/viewsolution/27629058 AC Solution

codenameghost · October 30, 2019, 5:30pm

Because of errors in input file??? Its a common issue thats why u dont use fast io

aryaman_arora · October 30, 2019, 5:31pm

I dont use fast IO generally but i copied dsu on tree code from a previous submission.

wadu_hekk · October 30, 2019, 5:33pm

that’s what you get for copying

aryaman_arora · October 30, 2019, 5:33pm

anon35303488 · October 30, 2019, 5:37pm

The best part is that the check(int N) function must be check(long long N). The guy was real lucky.

code_25 · October 30, 2019, 5:39pm

can u explain what logic he has used in this code…

nuttela · October 30, 2019, 5:55pm

Editorials will be uploaded soon.

introwitt · October 31, 2019, 3:01am

Is this contest(Encoding) rated ?

akay_99 · October 31, 2019, 3:03am

Encoding is a monthly organised contest of Netaji Subhash Engineering College,and it is not rated☺️

code_25 · November 2, 2019, 6:02am

can anyone explain the CORRECT solution for the problem GVR which follow the constraints and passes within the given time limit…

silvester14 · November 2, 2019, 6:07am

The perfect solution for this problem will be Miller Rabin Primality Test for checking prime, then its complexity in that case will be O(N*(lnN)^2)O(N∗(lnN) 2)