We’re halfway through the year and its time for our sixth Long Challenge of the year 2020. We invite you to participate in CodeChef’s June Long Challenge, this Friday, 5th June, 15:00 IST onwards The contest will be open for 10 days i.e. until 15th June.

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.

Joining me on the problem setting panel are: - Setters: Sahil sahi1422 Chimnani , Naman smartnj Jain , Vikas _wildfire_ Pandey , Vinit Vitz Solanki , Taranpreet taran_1407 Singh, Raja raja1999 Vardhan Reddy , Sofiia Sonechko Melnyk , Ildar 300iq Gainullin , Arthur arthur.nascimento Nascimento

• Admin : Teja teja349 Vardhan Reddy

• Tester: Felipe fmota Mota

• Editorialist & Post-Contest Streaming: Rajarshi RestingRajarshi Basu

• Statement Verifier: Jakub Xellos Safin

• Mandarin Translator: Hanlin Ioser Ren

• Vietnamese Translator: Team VNOI

• Russian Translator: Fedor Mediocrity Korobeinikov

• Bengali Translator: Mohammad solaimanope Solaiman

• Hindi Translator: Akash Shrivastava

Prizes

Top 20 performers in the Indian category and top 10 performers in the Global category will get CodeChef laddus, with which the winners can claim cool CodeChef goodies. First to solve each problem except challenge — 100 laddus. Know more here

Good Luck!
Hope to see you participating!!
Happy Programming !!

I invite you to experience 3 hours of uninterrupted coding experience at the March Lunchtime. This 3-hour contest will offer 5 challenging problems to solve. A showdown to reach the top spot. So sharpen your coding skills and get ready to pack your Lunchtime with a box of Code. And not forgetting about our Birthday Surprise, you stand to win Laddus, with double the chances.

The problem statements of the contest will be available in English, Hindi, Bengali, Russian, Mandarin, and Vietnamese. Also, if you have some original and engaging problem ideas, and you’re interested in them being used in the CodeChef's contests, you can share them here: www.codechef.com/problemsetting/new-ideas.

I hope you will participate with your fellow programmers and enjoy the contest problems. Joining me on the problem setting panel are:

• Setters:imAnik (Anik Sarker), phoenix71 (Saad Muhammed Junayed), [user:hasinfarhan] (Md. Farhan Hasin), TheFallenOne (Hasin Rayhan Dewan Dhruboo)

• Admin & Tester: teja349 (Teja Vardhan Reddy)

• Editorialist: taran_1407 (Taranpreet Singh)

• Statement Verifier: Xellos (Jakub Safin)

• Mandarin Translator: gediiiiiii (Gedi Zheng)

• Vietnamese Translator: Team VNOI

• Russian Translator: Mediocrity (Fedor Korobeinikov)

• Bengali Translator: solaimanope (Mohammad Solaiman)

• Hindi Translator: Akash Shrivastava

Contest Details:

Time: 28th March 2020 (1930 hrs) to 28th March 2020 (2230 hrs). (Indian Standard Time — +5:30 GMT) — Check your timezone.

• Contest link: www.codechef.com/LTIME82
• Registration: You just need to have a CodeChef handle to participate. For all those who are interested and do not have a CodeChef handle, are requested to register in order to participate.
• Prizes: Top 10 Indian and top 10 Global school students from ranklist will receive certificates and CodeChef laddus, with which the winners can claim cool CodeChef goodies. Know more here. Good Luck!
  Hope to see you participating!!
  Happy Programming!!

Hi guys!

I am going to be the new admin for Cook Offs from December onwards.

We are looking for problem sets for Cook offs to make Cook offs more appreciable. Send the ideas via e-mail to problems@codechef.com with the subject Cook Off (or Lunchtime if you want to submit for Lunchtime for which Hasan will be admin).

Also partial problem sets are welcomed. We will try to club them with other setters to complete the set.

Currently you can expect a turnaround time of within 5 days to get a reply on your submission from me.

Also I invite everyone to come forward and participate in the Cook offs and let know their opinions on the problemsets in future by commenting on the respective blog posts to help us improve.

UPD:

Currently we use 7 problems in Cook offs.Problem difficulties I expect them to be according to Codeforces (I will update soon based on codechef version):

Div2A, Div2B, Div2 B(little on the harder side)/ Div2C(avg or easy side ones) , Div1A, Div1B, Div1C, Div1D.

Also it would be great if you reply the solutions to the problems in a second mail replying to the first mail. It would help me in assessing problems without biases.

Greetings Codeforces Community!

I would like to invite you to participate in CodeChef October Lunchtime 2019. This is a 3-hour contest and everyone is welcome to participate and test their coding skills. And the problems are available in English, Hindi, Bengali, Russian, Mandarin and Vietnamese.

If you have any original and engaging problem ideas, and you’re interested in them being used in the CodeChef's contests, you can share them here: www.codechef.com/problemsetting/new-ideas.

I hope you will join your fellow programmers and enjoy the contest problems. Joining me on the problem setting panel are:

• Setter and Editorialist: Odin- (Jafar Badour)

• Tester: teja349 (Teja Vardhan Reddy)

• Statement Verifier: Xellos (Jakub Safin)

• Mandarin Translator: gediiiiiii (Gedi Zheng)

• Vietnamese Translator: Team VNOI

• Russian Translator: Mediocrity (Fedor Korobeinikov)

• Bengali Translator: solaimanope (Mohammad Solaiman)

• Hindi Translator: Akash Shrivastava

Contest Details:

• Start Date & Time: 26th October 2019 (1930 hrs) to 26th October 2019 (2230 hrs). (Indian Standard Time — +5:30 GMT) — Check your timezone
• Contest link: https://www.codechef.com/LTIME77
• Registration: You just need to have a CodeChef handle to participate. For all those who are interested and do not have a CodeChef handle, are requested to register in order to participate.
• Prizes: Top 10 Indian and top 10 Global school students from ranklist will receive certificates and CodeChef laddus, with which the winners can claim cool CodeChef goodies. Know more here: https://discuss.codechef.com/t/how-do-i-win-a-codechef-goodie/7344. Good Luck!
  Hope to see you participating!!
  Happy Programming!!

Greetings Codeforces Community!

CodeChef’s June CookOff, sponsored by ShareChat is almost here. Prepare to face the problem set that we have been busy brewing. This is your opportunity to showcase your programming skills amidst the best programmers in the world and better your ratings.

As a bonus: ShareChat — India’s fastest growing social network is seeking both interns and full-time employees to join their dynamic team. To be considered for the roles, all you have to do is fill the form provided and participate in the contest. Visit the contest page for more details.

We are on the hunt for a Mandarin Translator to help translate problem statements for our monthly contests. This will be a long-term commitment with translations required thrice a month. If you think you are up to the task, then do get back to us at problems@codechef.com.

There’s no time to waste, so start flexing your programming muscle. I hope you will join your fellow programmers and enjoy the contest problems. Joining me on the problem setting panel are:

• Setters: kingofnumbers (Hasan Jaddouh), Erfan.aa (Erfan Alimohammadi), solaimanope (Mohammad Solaiman)

• Tester and Editorialist: teja349 (Teja Vardhan Reddy)

• Statement Verifier: Xellos (Jakub Safin)

• Mandarin Translator: huzecong (Hu Zecong)

• Vietnamese Translator: Team VNOI

• Russian Translator: Mediocrity (Fedor Korobeinikov)

• Bengali Translator: solaimanope (Mohammad Solaiman)

• Hindi Translator: Akash Shrivastava

Contest Details:

• Start Date & Time: 23rd June 2019 (2130 hrs) to 24th June 2019 (0000 hrs). (Indian Standard Time — +5:30 GMT) — Check your timezone

• Contest link: https://www.codechef.com/COOK107

• Registration: You just need to have a CodeChef handle to participate. For all those, who are interested and do not have a CodeChef handle, are requested to register in order to participate.

• Prizes: Top 10 performers in Global and top 10 performers in Indian category will get CodeChef laddus, with which the winners can claim cool CodeChef goodies. Know more here: https://discuss.codechef.com/t/how-do-i-win-a-codechef-goodie/7344

(For those who have not yet got their previous winning, please send an email to winners@codechef.com)

Good Luck!

Hope to see you participating!!

Happy Programming!!

Hello CodeForces Community!

We are happy to extend our invitation to the November Cook-Off 2018 sponsored by ShareChat, a 2.5 hour test of your coding skills. As this is the 100th iteration of the contest, we have some additional exciting rewards for the contestants, which you can check out on the contest page.

There’s another reason to compete. ShareChat, the sponsor of November Cook-Off, is offering full-time job opportunities for programmers across the globe. More details about the additional rewards and job opportunities can be found on the contest page.

The contest problems will be available in English, Hindi, Bengali, Russian, Mandarin and Vietnamese. Joining me this time on the problem setting panel are:

Setter: PraveenDhinwa (Praveen Dhinwa)

Tester: teja349 (Teja Vardhan Reddy)

Statement verifier: Xellos (Jakub Safin)

Editorialist: taran_1407 (Taranpreet Singh)

Mandarin Translator: huzecong (Hu Zecong)

Vietnamese Translator: Team VNOI

Russian Translator: Mediocrity (Fedor Korobeinikov)

Bengali Translator: solaimanope (Mohammad Solaiman)

Hindi Translator: Akash Shrivastava

Contest Details:

Time: 18th November 2018 (2130 hrs) to 19th November 2018 (0000 hrs). (Indian Standard Time — +5:30 GMT) — Check your timezone

Contest link: https://www.codechef.com/COOK100

Registration: You just need to have a CodeChef handle to participate. For all those, who are interested and do not have a CodeChef handle, are requested to register in order to participate.

Prizes: Top 10 performers in Global and Indian category will get CodeChef laddus, with which the winners can claim cool CodeChef goodies. Know more here: https://discuss.codechef.com/questions/51999/how-do-i-win-a-codechef-goodie
(For those who have not yet got their previous winning, please send an email to winners@codechef.com)

Good Luck!
Hope to see you participating!!
Happy Programming!!

Hello Codeforces Community!

We would like to invite you to our next monthly contest and we’re sure you’ll enjoy — the October Lunchtime 2018 sponsored by Sharechat! Along with interesting problem sets, we have exciting full-time job opportunities by ShareChat for professionals across the globe. More details can be found on the October Lunchtime contest page.

Joining me this time on the problem setting panel are:

• Problem Setter: kingofnumbers (Hasan Jaddouh), PraveenDhinwa (Praveen Dhinwa)

• Problem Tester: teja349 (Teja Vardhan Reddy)

• Editorialist: taran_1407 (Taranpreet Singh)

• Statement Verifier: Xellos (Jakub Safin)

• Russian Translator: Mediocrity (Fedor Korobeinikov)

• Mandarin Translator: huzecong (Hu Zecong)

• Hindi Translator: Akash Shrivastav

• Bengali Translator: Imran Hasan

• Vietnamese Translator: VNOI Team

Contest Details:

Time: 27th October 2018 (1930 hrs — 2230 hrs). (Indian Standard Time — +5:30 GMT) — Check your timezone.

Contest link: https://www.codechef.com/LTIME65

Registration: You just need to have a CodeChef handle to participate. For all those, who are interested and do not have a CodeChef handle, are requested to register in order to participate.

Prizes: * Top 10 performers in Global and Indian category will get CodeChef laddus, with which the winners can claim cool CodeChef goodies. Know more here: https://discuss.codechef.com/questions/51999/how-do-i-win-a-codechef-goodie. (For those who have not yet received their previous winning, please send an email to winners@codechef.com)

Good Luck! Hope to see you at the contest!

Hello CodeForces Community!

We would like to invite you to our next monthly contest and we’re sure you’ll enjoy — the September Lunchtime 2018 sponsored by Sharechat! Get ready for a three-hour test of your coding brains and pit yourself against the best. And there’s more! We have exciting full-time job opportunities by ShareChat for professionals across the globe. More details can be found on the September Lunchtime contest page.

Joining me this time on the problem setting panel are:

• Problem Setter: kingofnumbers (Hasan Jaddouh)

• Problem Tester: teja349 (Teja Vardhan Reddy)

• Editorialist: taran_1407 (Taranpreet Singh)

• Statement Verifier: Xellos (Jakub Safin)

• Russian Translator: Mediocrity (Fedor Korobeinikov)

• Mandarin Translator: huzecong (Hu Zecong)

• Hindi Translator: Srijan Dubey

• Bengali Translator: solaimanope (Mohammad Solaiman)

• Vietnamese Translator: VNOI Team

Contest Details:

Time: 29th September 2018 (1930 hrs — 2230 hrs). (Indian Standard Time — +5:30 GMT) — Check your timezone.

Contest link: https://www.codechef.com/LTIME64

Registration: You just need to have a CodeChef handle to participate. For all those, who are interested and do not have a CodeChef handle, are requested to register in order to participate.

Prizes:

• Top 10 performers in Global and Indian category will get CodeChef laddus, with which the winners can claim cool CodeChef goodies. Know more here: https://discuss.codechef.com/questions/51999/how-do-i-win-a-codechef-goodie. (For those who have not yet received their previous winning, please send an email to winners@codechef.com)

Good Luck! Hope to see you at the contest!

I am thinking about hosting a stream soon after the contest to discuss the tasks from the contest.
What is your opinion on it?
Incase there is good response from community, I will host a stream discussing problems from the contest.

Stream Details:

I will be starting the stream at 10:40 pm IST ( 10 minutes after the contest) at https://www.twitch.tv/teja349 . I will try to take questions after solving each problem. I see there is a lag close to 1 minute on twitch. Is there a way to get rid of it or maybe my system resources cannot process,

Youtube link: https://www.youtube.com/watch?v=GJfD2PEY7pA .

Comments and suggestions are most welcomed!!

Hello CodeForces Community!

We’re excited to announce the September Long Challenge sponsored by ShareChat. Along with the opportunity to boost your ratings and win some cool laddus, there are some exciting full-time job opportunities with ShareChat for professionals across the globe. More details about the job opportunities can be found on the contest page.

• Problem Tester: teja349 (Teja Vardhan Reddy)

• Problem Setters: (Shivam Gupta ), XORier (Priyanshi Gupta), adamant (Oleksandr Kulkov ), step_by_step (Stepan Filippov), bciobanu (Bogdan Ciobanu), rajat1603 (Rajat De), DOlaBMOon (Max Hsia)

• Problem Editorialist: vijju123 (Abhishek Pandey)

• Statement Verifier: Xellos (Jakub Safin)

• Russian Translator: Mediocrity (Fedor Korobeinikov)

• Mandarin Translator: huzecong (Hu Zecong)

• Vietnamese Translator: VNOI Team

I hope you will enjoy solving them. Please give your feedback on the problem set in the comments below, after the contest.

Contest Details:

Time: 7th September 2018 (1500 hrs) to 17th September (1500 hrs). (Indian Standard Time — +5:30 GMT) — Check your timezone.).

Contest link: www.codechef.com/SEPT18

Registration: You just need to have a CodeChef handle to participate. For all those, who are interested and do not have a CodeChef handle, are requested to register in order to participate.

Prizes: Top 10 performers in Global and Indian category will get CodeChef laddus, with which the winners can claim cool CodeChef goodies. Know more here: discuss.codechef.com/questions/51999/how-do-i-win-a-codechef-goodie.
(For those who have not yet got their previous winning, please send an email to winners@codechef.com). First to solve each problem individually: 100 laddus (For problems common to both Divisions, only one user will get laddus for that problem).

Good Luck!
Hope to see you participating!!

Recently I participated and got Rank 2 in Quick Code conducted by NSIT on Codechef. In the poster, they have mentioned prizes worth 25K (hopefully INR). On Codechef, they mentioned Cash prizes worth 25K.

I was excited that the prize money would be somewhere between (5K to 10K) in cash for Rank 2.But yesterday,I have mail that it was prize coupon from Codechef worth 500 and some coupon code attached(Maybe for CCDSAP).

I knew the person who got Rank 1.He has received some coupon which was expected to expire in next 8 hours from the time of receival.Later he negotiated it to 200 Codechef Laddus(a great deal I guess).

I have contacted them regarding website saying it as Cash prizes.But they were like prizes which are worth that cash.I dont know how 200 Laddus + 500 INR coupon + maybe some more prizes for ranks after 2 = 25K.

Its not that I am unhappy with the contest(The problems were okayish).Since it is a university contest, I believe there must have been funds worth 25K allocated by the management.Also NSIT is considered to be among good institutes in India.Hence, this was not expected from them.

Also people might feel, it is bad to post this way.But I think it should be addressed in public because there was no intent from their side when I called them.Also I feel Codechef takes a lot of care regarding many other aspects of external contest. Maybe its time for them to take care of this part too after the contest.Because it adds to their reputation at the end of the day.I want to make it clear that I understand it is not responsibility of Codechef.

Coming back to the Title of blog post

I do not think I will use that coupon.So I thought I will give it to a random person. Hence I created this form.I will message the 10th distinct handle who fills this form with the details of the coupon code.

PS: I have also not received some shirts from Hackerrank yet from long back(atleast 3 months old).So does anyone know how to contact them regarding this.

Hi all,

We Computer Science Department at IIT Madras are hosting the contest comp.exe on Codechef(link) as part of our department fest Exebit.The contest will take place on 11th April,2018 at 21:00 IST.
The problemsetters and testers for the contest are me(teja349) and MegaBidoof. Thanks to TooDifferent for helping us in preparation of the contest.
I personally feel problemset is around Div2 level.There will be 8 problems with ACM type scoring.The contest is team contest (teams of 2).Duration is 120 minutes.

There are prizes worth 6K (only for Indian participants).

Registrations for prizes: Register here before the contest starts to be eligible for prizes. Hope you enjoy the contest!!!Good luck and have fun.

Lets discuss problems after contest (if any).

UPD: Contest starts in less than 1hr.All the best!!!

Thanks for the participation!!

We are sorry that for the question GCD Queries segment tree solutions and sparse solutions could pass. Though we had a solution with complexity of O((q+n)*log(MAX_element)).We leave it for you to try it.

I dont see any blog created for this contest.Also editorials seems to not be published yet.
My idea for E was bit long to code.But I see many people did it in short time.So can someone brief up with a good approach.
Also feel free to discuss other questions below.

Hi all
I am using Kubuntu 16.04
I write code in c++ and compile it using g++ .I think the version of c++ is c++ 11.
whatever be the reason i cannot use auto,unordered map and some other things in my pc.
I have googled quite a bit about updating to c++ 14 or some more advanced version which supports above things atleast.But in vain,I couldn't find any thing helpful that solves my problem.

Can someone help me how to run program in c++14 in my system??
And also I see some experienced coders compile program using something different rather than just
g++ prog.cpp Can someone elaborate on this ???

BTW Happy New Year to all of you

Assume there are 2 patterns P1 and P2 such that P1 is a substring of P2 which is nether prefix nor suffix.Then how does a KMP type on string T work
Eg:
P1=of
P2=sofa
T=sofa
in this if we run aho corasick .will it detect string "of" or not

And also any good tutorial link on it will be apreciated
PS:I havent implemented it yet.I was studying it and I got this doubt as I read about its implementation

I have observed a fact while solving . The complexity of lower bound varies with type of iterator passed to it.

But a more weird fact is
1. the below lower bound takes O(log(n)) time
~~~~~ multiset< ll > set1; //some insert operation on multiset it=set1.lower_bound(val); ~~~~~

the question is Vasiliy's Multiset

here is my submission in which it took O(logn) when i used in above format here