Hii Codeforces!

We are pleased to invite you all to CodeChef's Starters 30, aka International Coding Marathon, in collaboration with Technex '22, IIT-BHU.

ICM is the flagship CP event of Byte the Bits, the set of programming events organized under Technex, the annual techno-management fest of the Indian Institute of Technology (BHU), Varanasi. It is scheduled for 8PM IST (in about 4 hours from now) on the CodeChef platform.

Here is the contest link: CodeChef Starters 30

The contest is rated for Divisions 2 through 4. However, it is on the challenging side and has problems that will be interesting for Division 1 participants too (~~Prove your solutions!~~).

I'd like to thank

- The problem setters: Anshu CoderAnshu Garg, Jatin rivalq Garg, Kushagra koderkushy Goel, Eshaan XORring-Samurai Gupta, Pranav pd_codes Dev, Piyush piyush_pransukhka Pransukhka, Kartik Gokussjz Malik, Saritesh saritesh Tiwari, Thakur pertifiedcobra Abhishek, Ashish Ashishgup Gupta and Utkarsh Utkarsh.25dec Gupta.
- The testers: Abhinav abhinavvv306 Sharma, Aryan aryanc403 Choudhary.
- the Statement verifier: Kanhaiya notsoloud1 Mohan.
- the editorialists: Prakhar prako_87 Kochar, Lavish lavish315 Gupta.
- the contest admins: Ashish Ashishgup Gupta and Utkarsh Utkarsh.25dec Gupta.
- You, the participants!

Cash prizes for the fast and precise! (Combined ranklist for div 1 and 2)

- Global rank 1:
`10'000`

INR - Global rank 2:
`6'000`

INR - Global rank 3:
`4'000`

INR

Fill out this form to avail them.

Some of our previous rounds:

The video editorials of the problems will be available on Codechef's YouTube channel as soon as the contest ends. Subscribe to get notifications about new editorials.

Also, if you have some original and engaging problem ideas, and you’re interested in them being used in CodeChef's contests, you can share them here.

Good luck. Let's give the CC servers some numbers to crunch!

The editorial is out.

Congratulations to the winners (Combined ranklist for div 1 and 2):

As one of the problemsetters, I assure you that the problemset is very interesting.

As a problemsetter, the problemset is very exciting and fun to solve.

As a problemsetter of atleast one of the problems, I tried making the problem statement short and interesting.

As a problemsetter, the problems are very interesting and I recommend you to read all the problems.

meme...

Yet another memeit was good, thanks

I went for shit, PRESUF had 90 AC submissions, came back and now it has 250+ XD.

Infamous golden hour of Codechef

Calculating the LIS of a sequence with element deletions (used in solving Maximizing LIS) is also used in this Atcoder Problem

was elements deletion required? I just calculated lis of prefix and decreasing subsequence from suffix and calculated the maximum answer.

In last 5 mins 100 people submitted PRESUFOP XDD

How to solve Prefix Suffix Operations? For N >= 2, if it's possible then the answer is obviously the sum of the difference between the corresponding extreme elements of the array, but what are the necessary conditions?

https://www.codechef.com/viewsolution/60546801 can anybody tell any edge case for which my solution failing in 1 case out of 5 plz tell if anyone knows any edge case??

your code fails in the following case:

it becomes

which used 4 colours. actual answer is

In PRESUFOP, I assumed there is no solution when there is more than one local maximum in the difference array B — A (not counting first and last). Is this correct?

Div-1 and Div-2 had same questions?

yes

Fun Fact: In Div4 out of the 360 people that AKED (solved all problems during the contest) more than 200 have the same institute listed on their codechef account.

contest is really good,i learn lot of thing, thanks for the great problemset _ /\ _

Auto comment: topic has been updated by koderkushy (previous revision, new revision, compare).