Lecture 1 : Persistence segment tree with its applications and merge sort tree. By Sergey Kulik.
Problems:
Lecture 2: Fast Fourier Transform and its applications. By Kevin Charles Atienza.
Lecture 3: Max flow with its applications. By Anudeep Nekkanti
Lecture Video
List of Problems:
Lecture 4: Zeta Function and its applications to optimizations in dynamic programming. By Arjun Arul.
Lecture Video
Sample problems:
References for Yate’s DP, Fast Zeta and Mobius transforms
For further reading:
Lecture 5: Centroid decomposition and use of reflections in some combinatorial problems. By Akashdeep Nain
Lecture Video
Please check the following link for an amazing reference about the concept and related problems on Centroid Decomposition https://threads-iiith.quora.com/Centroid-Decomposition-of-a-Tree
Team Name: ancalagon
Team Members: Balajiganapathi S & Deepa Panwar
Institution/Organization: IIT Bombay
SnackDown 2015 Rank: Indian 18
Q. CodeChef: When did you start coding and how did you learn?
Balajiganapathi S: There was a programming course in my school during 7th standard. We were taught programming using GW BASIC. Later I learnt C/C++ and all the algorithms using materials available online on my own.
Deepa Panwar: I first got introduced to coding in B.Tech 1st year coding lab. I learnt coding mostly from assignments, class and books.
Q. CodeChef: Could you name and share your first programming contest experience?
Balajiganapathi S: Topcoder SRM 443 in June 2009 was my first contest. I only knew C and did not knew C++ much. I had to keep googling how to do basic things like looping through a vector. Yet I managed to solve the easiest problem.
Deepa Panwar: My first coding contest was Topcoder SRM 608. I solved level one and level two problem successfully, it was thrilling.
Q. CodeChef: How often do you code on any given day & weekend?
Balajiganapathi S: I stopped practising after last year’s ICPC World Finals due to time constraints. However, I try to keep participating in as many contests as possible. I try not to miss any contest on CodeChef, topcoder and codeforces.
Deepa Panwar: I always try to participate in all contest. And do coding when I get bored of academics, which is often 
Q. CodeChef: What was the biggest hurdle on your road to where you are today?
Balajiganapathi S: Managing academics. Since my branch in Bachelors was Electronics and Telecommunication, I had to balance between coding and obtain passing marks in the exams. There have been conflicts with exams and contests. I participated in ICPC 2011 Amrita regionals even though there was a 7th semester endsem exam the next day. I failed in the exam. Due to some university rules, I had to give all the exams of 7th semester again. So, I had to study for 8 subjects during my final semester endsems.
Deepa Panwar: Lack of proper guidance or proper resources.
Q. CodeChef: What do you think biggest mistake competitive programmers make?
Balajiganapathi S: I have noticed 2 mistakes that many competitive coders make: 1. Coding for the wrong reasons: Some coders code just to add it to their resume. I feel this is a wrong reason to code. If competitive coding is not interesting, one should not participate just for adding it to their resume. 2. Giving up early: Learning basic algorithms is fun and it is easy to be motivated as we can get AC on easy problems after learning those algos. However after a point, many come across difficult problems which require a lot of thinking and do not easily reduce to basic algorithms. Many coders give up at this point..
Deepa Panwar: Caring too much about rating.
Q. CodeChef: What programming language do you use and why?
Balajiganapathi S: C++: STL is awesome and Java code looks very verbose compared to C++. .
Deepa Panwar: C++, because it provides STL, which helps in fast coding.
Q. CodeChef: What advice do you have for other competitive programmers?
Balajiganapathi S: Don’t give up!
Deepa Panwar: Keep calm and code on.
Q. CodeChef: What do you like the most about CodeChef? and what would you don’t like in it?
Balajiganapathi S: Like: Snackdown. I really like the idea of an India centric onsite contest. Please make this an annual event 
Dislike: Server errors and slow page load at the start of cook offs annoy me a lot. However, it has been getting better over the last few contests. Hope it goes away entirely.
Deepa Panwar: I like CodeChef editorials.
Q. CodeChef: What factors do you believe help you win?
Balajiganapathi S: It doesn’t matter whether you win or lose as long as you do your very best
Deepa Panwar: Self motivation.
Q. CodeChef: What motivates you to compete?
Balajiganapathi S: I like competitive coding.
Deepa Panwar: I just like the feeling when I see AC or System Tests Passed.
Q. CodeChef: Where do you see yourself 5 years down the line?
Balajiganapathi S: 5 years is too long!
Deepa Panwar: I don’t think that far
That, ladies & gentlemen is Team ancalagon to you. We thoroughly enjoyed their responses and hope you did too.
We will be back soon, so keep watching this space.
Regards,
Rudreshwar
Team CodeChef
Team Name: rooks_nitk
Team Members: Vadiraja K & Aadheeshwar Vijayakumar
Institution/Organization: National Institute of Technology Karnataka
SnackDown 2015 Rank: Indian 15
Q. CodeChef: When did you start coding and how did you learn?
Vadiraja K: I learnt c++ in high school; it was part of our curriculum
Aadheeshwar Vijayakumar: I started coding in 8th but competitive coding only in B. Tech 1st year. I learn from Q. CodeChef practicing problem, Topcoder tutorials, GeeksForGeeks, CodeForces.
Q. CodeChef: Could you name and share your first programming contest experience?
Vadiraja K: It was CodeChef October long 2013 I had just started competitive coding and was able to solve 4 questions. Those 4 green ticks made me very happy and got me into competitive coding
Aadheeshwar Vijayakumar: CodeChef Long Challenge. I solved only 3/4 questions but this gave me confidence & motivated me to learn more. The very next contest I coded 7/8.
Q. CodeChef: How often do you code on any given day & weekend?
Vadiraja K: Couple of hours
Aadheeshwar Vijayakumar: I code regularly. I make sure I participate at least in 1 contest per week.
Q. CodeChef: What was the biggest hurdle on your road to where you are today?
Vadiraja K: Laziness 
Aadheeshwar Vijayakumar: Time Management it’s crucial and also not making silly mistakes as penalties are too costly especially in short contests.
Q. CodeChef: What do you think biggest mistake competitive programmers make?
Vadiraja K: Going after points and rankings than learning
Aadheeshwar Vijayakumar: Time management and trying same question if stuck, we must probably give another question a try.
Q. CodeChef: What programming language do you use and why?
Vadiraja K: C++ I’ve been coding in c++ since high school so I’m more comfortable with it and it’s faster than most other languages
Aadheeshwar Vijayakumar: I prefer C++ due to my knowledge in the same and STL makes it easy to code.
Q. CodeChef: What advice do you have for other competitive programmers?
Vadiraja K: Start early! And never give up!
Aadheeshwar Vijayakumar: Keep Coding and Practicing.
Q. CodeChef: What do you like the most about CodeChef? And what would you don’t like in it?
Vadiraja K: Long contests are so much fun and a very nice learning experience it helped me a lot! I don’t like that in every cook off there’s some problem at the start
Aadheeshwar Vijayakumar: Good standard problems, nice editorials. CodeChef can train student in advanced coding concepts and its implementation thru camps and online tutorials by experts.
Q. CodeChef: What factors do you believe help you win?
Vadiraja K: Faster coding and a never give up attitude
Aadheeshwar Vijayakumar: Hard work, Determination, Perseverance, Leadership, Team Spirit.
Q. CodeChef: What motivates you to compete?
Vadiraja K: The green tick!
Aadheeshwar Vijayakumar: To learn more and nothing can match the sweetness of success.
Q. CodeChef: Where do you see yourself 5 years down the line?
Vadiraja K: In some IT firm coding my heart out!
Aadheeshwar Vijayakumar: As an Entrepreneur.
That, ladies & gentlemen is Team rooks_nitk to you. We thoroughly enjoyed their responses and hope you did too.
We will be back soon, so keep watching this space.
Regards,
Rudreshwar
Team Q. CodeChef
Team Name: ench_mango
Team Members: Kelvin & Pi-Hsun Shih
Institution/Organization: National Taiwan University
SnackDown 2015 Rank: ROW 06
Q. CodeChef: When did you start coding and how did you learn?
Kelvin: High school mostly, joined a informatic club and otherwise self-taught for the most part.
Pi-Hsun Shih: When I was 10 years old. I learned VB by reading a book.
Q. CodeChef: Could you name and share your first programming contest experience?
Kelvin: Probably some internal contest when I was in the informatics club hosted by some random guy (who is known as tmt514 today)!. I came in the contest oddly confident considering it’s my first time, probably due to I solved ~200 easy problems on UVa judge and thought I am ready to earn turing award. Not surprisingly I was crushed in terms of the number of problems I solved — only around half of them. But still I’m really happy, that’s when I became even surer that the thrill of competitive programming will never part with me.
Pi-Hsun Shih: My first programming contest experience was some contest in senior high school.
Q. CodeChef: How often do you code on any given day & weekend?
Kelvin: 6+ hours on average?
Pi-Hsun Shih: Depends on whether there’s programming contest or not 
Q. CodeChef: What was the biggest hurdle on your road to where you are today?
Kelvin: Don’t feel anything on the road is a hurdle. It’s either pain or fun or neither, but whichever it is it’s what the road is made of.
Pi-Hsun Shih: .
Q. CodeChef: What do you think biggest mistake competitive programmers make?
Kelvin: Other than integer overflow, reading the problem statement wrong, wrongly allocating array size, forgetting to return, and typing i instead of j? It must be ignoring girlfriend for 24 hours because we had to participate in some day-long contest, then .
Pi-Hsun Shih: Getting nervous and write a hard solution for an easy problem.
Q. CodeChef: What programming language do you use and why?
Kelvin: C++ in competitive programming for it’s efficiency and I don’t like java much.
Pi-Hsun Shih: For programming contest: C++. Just used to it. For other: Ruby!
Q. CodeChef: What advice do you have for other competitive programmers?
Kelvin: Use 50216 or 514 as your random seed. Brings good luck.
Pi-Hsun Shih: .
Q. CodeChef: What do you like the most about CodeChef? and what would you don’t like in it?
Kelvin: I don’t really compete on CodeChef much, still. There are many languages one can choose, which is nice; On the other hand based on my limited experience competing on CodeChef, the browsing interface is a bit awkward..
Pi-Hsun Shih: Haven’t used CodeChef much, so nothing to say.
Q. CodeChef: What factors do you believe help you win?
Kelvin: Hardwork and peter50216.
Pi-Hsun Shih: Practice and good teammate
Q. CodeChef: What motivates you to compete?
Kelvin: Excellence? That too old? Seriously though thrill, joy, and nothing else.
Pi-Hsun Shih: Because it’s fun.
Q. CodeChef: Where do you see yourself 5 years down the line?
Kelvin: A happy place? (Not the happy place Momma used to speak of when we’re little)
Pi-Hsun Shih: No idea.
That, ladies & gentlemen is Team ench_mango to you. We thoroughly enjoyed their responses and hope you did too.
We will be back soon, so keep watching this space.
Regards,
Rudreshwar,
Team CodeChef
Team Name: crteam
Team Members: Roman Udovichenko & Aliaksei Tolstsikau
Institution/Organization: Yandex
SnackDown 2015 Rank: ROW 17
Q. CodeChef: When did you start coding and how did you learn?
Roman Udovichenko: I started coding when I was 12. I learned about programming from my school teacher.
Aliaksei Tolstsikau: In 2003. Practice, practice and once more practice.
Q. CodeChef: Could you name and share your first programming contest experience?
Roman Udovichenko: My first programming contest experience was regional olympiad in informatics. I did not very well, because I was 13 at that time
Aliaksei Tolstsikau: Belarusian state university contest in 2004 (preliminary round of regional ACM ICPC).
Q. CodeChef: How often do you code on any given day & weekend?
Roman Udovichenko: I code very much, every day on my job and in the free time. I think I spent about 50 hours a week on coding.
Aliaksei Tolstsikau: Couple years ago I coded 4-6 hours per week, now only 1-2 per week.
Q. CodeChef: What was the biggest hurdle on your road to where you are today?
Roman Udovichenko: I can’t remember any hurdles.
Aliaksei Tolstsikau: After wedding I still had time to compete a lot, but now I have two sons and don’t have time for trainings.
Q. CodeChef: What do you think biggest mistake competitive programmers make?
Roman Udovichenko: Hmmm… maybe being lazy and not practicing a lot.
Aliaksei Tolstsikau: They don’t learn any code style.
Q. CodeChef: What programming language do you use and why?
Roman Udovichenko: I use C++ because of its speed and Python with its great module system and nice language syntax.
Aliaksei Tolstsikau: C++. Just a habbit.
Q. CodeChef: What advice do you have for other competitive programmers?
Roman Udovichenko: Practice a lot.
Aliaksei Tolstsikau: Try to solve problems that you did not solve early!
Q. CodeChef: What do you like the most about CodeChef? and what would you don’t like in it?
Roman Udovichenko: I like contests with prizes. I don’t like if test data for some problem is wrong..
Aliaksei Tolstsikau: SnackDown is great!
Q. CodeChef: What factors do you believe help you win?
Roman Udovichenko: My experience.
Aliaksei Tolstsikau: A strong teammate.
Q. CodeChef: What motivates you to compete?
Roman Udovichenko: Prizes.
Aliaksei Tolstsikau: Challenges and prizes
Q. CodeChef: Where do you see yourself 5 years down the line?
Roman Udovichenko: I think I will be a team leader of small group.
Aliaksei Tolstsikau: Ph. D. in Computer Science.
That, ladies & gentlemen is Team crteam to you. We thoroughly enjoyed their responses and hope you did too.
We will be back soon, so keep watching this space.
Regards,
Rudreshwar
Team CodeChef
Team Name: believe
Team Members: Vivek Hamirwasia & Pulkit Goel
Institution/Organization: IIIT Hyderabad
SnackDown 2015 Rank: Indian 20
Q. CodeChef: When did you start coding and how did you learn?
Vivek Hamirwasia: I was introduced to programming in my 11th std as a part of the curriculum. I learned basic C++ syntax and semantics along with few simple algorithms like sorting, searching etc and basic data structures like stack and queues during this period.
Pulkit Goel: I qualified for the IOI training camp and got to know about competitive programming from there. I didn’t practice much until I started college. I learnt by practicing on various online judges.
Q. CodeChef: Could you name and share your first programming contest experience?
Vivek Hamirwasia: Interestingly, my first programming contest experience was when CodeChef visited IIIT Hyderabad in 2010 to hold an internal contest. I was at once drawn to the concept of solving problems under time pressure. I was delighted to be able to solve one out of the three problems in that contest, and that marked the start of my journey to become a serious competitive programmer.
Pulkit Goel: My first contest was INOI-2009. I didn’t know anything about algorithms at that time. The first question in the contest, was to count the minimum number of adjacent swaps to sort an array. I guessed that the minimum would occur if I sorted the array normally, using bubble sort, as taught in school. This contest didn’t have a portal, and all submissions were to be zipped and sent to the organizer. Finally when the list of qualifiers was released, I wasn’t on the list. But later I found out that this was because my code wasn’t compiling because of a spurious ‘]’ in it. It turned out that on removing that brace, my code compiled and worked fine. So then I was added to the list of qualifiers
Q. CodeChef: How often do you code on any given day & weekend?
Vivek Hamirwasia: On an average, I code around 2-3 hours on any given day. Since most of the online contests are scheduled on weekends, the average goes up to 7 hours on weekends.
Pulkit Goel: I don’t have a fixed amount of time that I spend on coding. I just do it when I feel like.
Q. CodeChef: What was the biggest hurdle on your road to where you are today?
Vivek Hamirwasia: The biggest hurdle was when my abilities had saturated to a certain point and I found it hard to improve further. I realized I could do easy-medium problems with ease but never the hard ones. I realized there had to be some sort of “activation energy” required for me to take the leap to the next level. Overcoming this phase required identification of my weak areas and spending hours to learn harder techniques. Turns out my greatest weakness was just the lack of patience.
Pulkit Goel: I guess awareness was the biggest hurdle. Maybe if I had known about competitive programming before, I could have been better at it.
Q. CodeChef: What do you think biggest mistake competitive programmers make?
Vivek Hamirwasia: This is related to the previous answer. The biggest mistake that I’ve observed many competitive programmers make is that they do not consciously try to improve after a certain level. They end up solving easy-medium problems very fast but have no idea on how to tackle the hard ones. As a result, their abilities reach a stand-still and they do not grow up the ladder. Many want immediate results and do not have the patience to spend some weeks grasping new ideas and implementing the same.
Pulkit Goel: I don’t think there’s a specific mistake. Everyone makes different kinds of mistakes. The point of practice is to reduce the rate at which these mistakes occur.
Q. CodeChef: What programming language do you use and why?
Vivek Hamirwasia: I use C++ because it encompasses the best of speed and easy of coding. The STL library is extremely useful for competitive programming. Moreover, I am quite comfortable with it since it was the first programming language I ever learned.
Pulkit Goel: C++. I’ve just gotten very used to it.
Q. CodeChef: What advice do you have for other competitive programmers?
Vivek Hamirwasia: There is no single advice that can apply to all competitive programmers. I think it is important for one to identify one’s own weak areas and improve upon them. I have found reading and understanding the editorials of problems followed by implementing them itself an effective tool to improving performance considerably.
Pulkit Goel: I guess you should do contests for fun and leave it as soon as you find that it’s a burden.
Q. CodeChef: What do you like the most about CodeChef? And what would you don’t like in it?
Vivek Hamirwasia: CodeChef has selflessly uplifted the competitive programming performance of the country by frequent contests and awareness campaigns. It has grown into a platform recognized by the greatest competitive programmers in the world. I cannot thank CodeChef enough for all the experience it has provided me with its numerous quality contests and events. It would be great if CodeChef could change the design and color of the Tshirts given for long and short contests.
Pulkit Goel: It was the first online contest platform that I participated in. I like that I get 10 days to think about the problems, and I can think of them whenever I feel like. Most of the hard techniques that I’ve learnt, were in CodeChef long contests. There’s nothing specific that I don’t like. Maybe the t-shirt design has gotten really old and needs to be changed.
Q. CodeChef: What factors do you believe help you win?
Vivek Hamirwasia: I believe my team name being believe_iiith would definitely help us win.
Pulkit Goel: Practice and a bit of luck.
Q. CodeChef: What motivates you to compete?
Vivek Hamirwasia: I have been an obsessed competitive programmer for quite some time now. It is safe to say my motivation lies with seeing the green tick on getting a solution accepted.
Pulkit Goel: The thrill of getting an accepted on hard problems.
Q. CodeChef: Where do you see yourself 5 years down the line?
Vivek Hamirwasia: As a child, I have always dreamed about contributing something significant to the world and I see myself making that very contribution 5 years down the line. I don’t have any idea what the contribution would be or how I would do it but if I had to take a guess, it would most likely be me starting up a company.
Pulkit Goel: I haven’t really thought about this, but I guess I would be working in some company, or if I’m lucky enough to get an idea, on a startup.
That, ladies & gentlemen is Team Believe to you. We thoroughly enjoyed their responses and hope you did too.
We will be back soon, so keep watching this space.
Regards,
Rudreshwar
Team CodeChef
Team Name: doctorwho
Team Members: Rahul Sunil Purohit & Abhra Dasgupta
Institution/Organization: Indian Institute of Technology Kanpur
SnackDown 2015 Rank: Indian 25
Q. CodeChef: When did you start coding and how did you learn?
Rahul Sunil Purohit: I came to know about competitive coding and online judges in August 2013 from fellow batch-mate. I started doing it from Nov 2013. I gave much efforts after completion of first year of M.Tech i.e from June 2014.
Abhra Dasgupta: I have been coding since 2012. I mainly started practicing on SPOJ and that is when I learnt a few things, but I also a lot from the profs here at IIT Kanpur.
Q. CodeChef: Could you name and share your first programming contest experience?
Rahul Sunil Purohit: It was IITK Weekly Coding Competition. I used to code in Turbo C prior to this and was not aware of C++ or gcc compiler. I write code for easy problem and it was working fine on my machine but was not acceptable on judge. I was ashamed to asked anyone why it is not working. I tried for four hours. After contest I asked my friend which editor he used to code and then I came to know about my mistake. It was much embarrassing moment. But now its one of funny moments.
Abhra Dasgupta: First programming contest was at the tech-fest of some college. Now when I look back at it, I could see myself struggling on easy problems and writing unclean long codes. But still it was fun.
Q. CodeChef: How often do you code on any given day & weekend?
Rahul Sunil Purohit: Six months before I used to code 3 hours a day. Now I occasionally participate in contests.
Abhra Dasgupta: I code anytime I get bored or feel like doing so. Problem solving is fun.
Q. CodeChef: What was the biggest hurdle on your road to where you are today?
Rahul Sunil Purohit: I guess not having awareness till my M.Tech was biggest drawback. But, as one says you can never rely on ifs and then in life. It was most amazing journey till this time. Thanks to CodeChef for wonderful contest, problems and editorials.
Abhra Dasgupta: Holding on to hope when initially nothing or a very few things used to get solved.
Q. CodeChef: What do you think biggest mistake competitive programmers make?
Rahul Sunil Purohit: According to me, its sports and one excels with practice. People think about it as talent but its skill.
Abhra Dasgupta: Over confidence. Not reading the problem properly.
Q. CodeChef: What programming language do you use and why?
Rahul Sunil Purohit: C++. Its the one which I know
Abhra Dasgupta: C++. Fast language and easier to to code using STL.
Q. CodeChef: What advice do you have for other competitive programmers?
Rahul Sunil Purohit: Compete, compete and compete. Make your juniors aware of competitive programming and just share your experiences with them, motivate them to do coding. That’s the way to bring India at Top in ICPC and other programming contests.
Abhra Dasgupta: Just keep practicing. Practice is the ultimate key to success.
Q. CodeChef: What do you like the most about CodeChef? and what would you don’t like in it?
Rahul Sunil Purohit: I like mostly the simple user interface. I love long contests. Those are the way to excel and think on some really cool problems.
Abhra Dasgupta: I really love the regular contest and professionalism in preparing and conducting them. I really dislike the frequently crashing platform during contests.
Q. CodeChef: What factors do you believe help you win?
Rahul Sunil Purohit: Our team work I must say. We are very good as a Team.
Abhra Dasgupta: Persistence and perseverance.
Q. CodeChef: What motivates you to compete?
Rahul Sunil Purohit: Well its recognition you get. But man that awesome feeling when you see green tick on screen after much hard-work. That feeling drives me to keyboard.
Abhra Dasgupta: Passion and love for algorithms.
Q. CodeChef: Where do you see yourself 5 years down the line?
Rahul Sunil Purohit: Not sure about place but wherever I will be, I will still be having my learning cap on.
Abhra Dasgupta: As a founder of a successful start-up or working somewhere where I really enjoy working and climbing the ladders of success.
That, ladies & gentlemen is Team doctorwho you. We thoroughly enjoyed their responses and hope you did too.
We will be back soon, so keep watching this space.
Regards,
Rudreshwar
Team CodeChef
Team Name: thenextgen
Team Members: Pramod & Rachamadugu Shiva Tejesh
Institution/Organization: IIT Roorkee
SnackDown 2015 Rank: Indian 11
Q. CodeChef: When did you start coding and how did you learn?
Pramod: In my B.Tech 2nd year, I learnt from different competitive coding platforms like spoj, codeforces, CodeChef.
Rachamadugu Shiva Tejesh: Since 2012, and learned from online
Q. CodeChef: Could you name and share your first programming contest experience?
Pramod: I don’t exactly remember the contest. I guess it was ACM ICPC Amritapuri qualifier round. We were able to solve three problems and I still remember we coded an O(n^3) solution which should not have passed for the given constraints, but we optimised it so it was accepted ( ) and we were selected for regionals for this.
Rachamadugu Shiva Tejesh: Couldn’t remember
Q. CodeChef: How often do you code on any given day & weekend?
Pramod: Whenever I find sometime, be it a weekend or a weekday I try to think of an app to develop or participate in contests.
Rachamadugu Shiva Tejesh: 2hrs a day
Q. CodeChef: What was the biggest hurdle on your road to where you are today?
Pramod: Trying to focus both on web/app development and competitive programming.
Rachamadugu Shiva Tejesh: Lack of proper learning environment
Q. CodeChef: What do you think biggest mistake competitive programmers make?
Pramod: For me it was giving up easily when I find an algo difficult to understand or a problem difficult to solve. I wish I had stuck to that with a little patience so my basics would have been clear.
Rachamadugu Shiva Tejesh: To not follow the editorials
Q. CodeChef: What programming language do you use and why?
Pramod: I use C++ for competitive programming as I’m familiar with it since a long time and so I can easily implement many data structures using this.
Rachamadugu Shiva Tejesh: C++ because it was thought in the university
Q. CodeChef: What advice do you have for other competitive programmers?
Pramod: I don’t think I’m qualified enough to advice others, but if there is one thing I would like to change the way I learnt it would be to perfectly learn the algo/basics and then try solving many problems on it rather than partially learning the algo and trying to satisfy myself solving the problem which led to learning the algo
Rachamadugu Shiva Tejesh: Have fun with programming
Q. CodeChef: What do you like the most about CodeChef? and what would you don’t like in it?
Pramod: The CodeChef rating system is a bit weird. But otherwise, the Long Contest are really what is special about CodeChef.The platform is easy to understand and navigate better. But the partial delays in contests and the website slowing down during contests are somethings which I want CodeChef to improve
Rachamadugu Shiva Tejesh: CodeChef creates a wonderful platform to have regular practise through contests but the prizes(T-Shirts) are not exciting. Few people get tens of TShirts which they wont use
Q. CodeChef: What factors do you believe help you win?
Pramod: Focussing on one small goal at a time and I personally feel taking 1000 small steps is better than taking one gigantic step.
Rachamadugu Shiva Tejesh: Pleasant Mind, speed
Q. CodeChef: What motivates you to compete?
Pramod: The interest in competitive programming and learning new things
Rachamadugu Shiva Tejesh: Victory
Q. CodeChef: Where do you see yourself 5 years down the line?
Pramod: May be learning some more new things and contribute my part wherever I am.
Rachamadugu Shiva Tejesh: To become one of the Worlds Best competitive programmer
That, ladies & gentlemen is Team thenextgen to you. We thoroughly enjoyed their responses and hope you did too.
We will be back soon, so keep watching this space.
Regards,
Rudreshwar,
Team CodeChef
Team Name: dps_dwarka
Team Members: Rajat De & Additya Popli
Institution/Organization: Delhi Public School, Dwarka
SnackDown 2015 Rank: Wild Card.
Q. CodeChef: When did you start coding and how did you learn?
Rajat De: I started coding last year around July-august (2014) when IIIT – D was conducting its junior programming event and I got to know about it through my seniors at school. Initially it were my friends at school who were coding much before I started who taught me basic stuff until I was good enough to understand algorithms myself from the internet .
Additya Popli: I started coding last year only, around July-August. My Computer Science teacher got me started, and my seniors helped me.
Q. CodeChef: Could you name and share your first programming contest experience?
Rajat De: My first online programming contest was procon junior prelims on CodeChef. I solved 2 out of 7 questions in that and just made it to the finals, then I went for the onsite finals, saw many other good coders and also the CodeChef team was there and I saw how interesting coding was, also in finals I couldn’t solve anything for full points I just ended up doing 1 partial question. But since then I started coding properly daily.
Additya Popli: It was IIITD’s Procon Junior. I’d just started programming and was very excited when I qualified for the onsite round. But sadly I wasn’t able to take part in the onsite round.
Q. CodeChef: How often do you code on any given day & weekend?
Rajat De: I mostly sit in front of my computer for full day, although my internet is a bit weak, but whenever it is working I spend my time on CodeChef and codeforces or spoj doing questions, on a weekend or any day off, I spent like 10 – 12 hours in front of my laptop out of which I spend like 6 – 7 hours coding, on working days it’s the half of it.
Additya Popli: Earlier I used to code almost every day. Nowadays, it has become very less, barely twice a week.
Q. CodeChef: What was the biggest hurdle on your road to where you are today?
Rajat De: One of the hurdles was weak internet connection, sometimes while doing a contest, my net goes and I can’t make a submission even if I have coded the solution. Other than that some hurdles include lack of good study material for advanced topics, most of the reading material for advanced topics is in Russian and the translators don’t work that well on those. So I had a hard time understanding some data structures and still have that problem.
Additya Popli: I could not qualify the Indian Nation Olympiad of Informatics last time. I’m yet to cross that hurdle. Hopefully, this time I will.
Q. CodeChef: What do you think biggest mistake competitive programmers make?
Rajat De: I have seen during live contests like CodeChef long challenges , people ask questions related to some question in that contest on codeforces blogs or stack overflow , I even receive some messages on codeforces from anonymous people asking for solutions , I think contests like long challenge are fun to solve and there is no point in asking the solutions .
Additya Popli: Carelessness. Solving one hard problem is always better than solving ten easy problems.
Q. CodeChef: What programming language do you use and why?
Rajat De: I use C++ right now, it’s because it was taught in schools in 11th and so while I started competitive programming it was the only language which I knew and was available in the list of languages. I still use it because it’s very fast, same thing in c++ works like 2 – 3 times faster than java and almost 5 times faster than python, C++ has all STL objects which we might need. Though I am sometimes jealous of python users as they have much more inbuilt functions than c++ but still considering speed, C++ is much better.
Additya Popli: I like C++. But, I like python better. It’s much easier and simpler, especially when you’re lazy!
Q. CodeChef: What advice do you have for other competitive programmers?
Rajat De: Just keep practicing on CodeChef / codeforces / spoj and any other online judge known to us, and if have any doubts ask them (not during contest). That’s it.
Additya Popli: While (alive) code;
Q. CodeChef: What do you like the most about CodeChef? And what would you don’t like in it?
Rajat De: I like the quality of some questions, there are some very good questions which are totally unique, and also the long challenge is pretty fun. What I don’t like is that recently in all CodeChef contests, there is too much math, and especially in lunchtimes, there are many math questions or questions which are totally off topic from IOI syllabus. Also one more thing I like about CodeChef is the editorials , some editorials are really interesting and have a lot of information , compared to codeforces editorials , CodeChef editorials are much more detailed .
Additya Popli: CodeChef is great for practice. But sometimes, in the Lunchtime contests, the questions are more Math than programming. Also, virtual contests would really help since people miss out on contests sometimes.
Q. CodeChef: What factors do you believe help you win?
Rajat De: The feeling we get after solving many questions in a contest is nice.
Additya Popli: The cool prizes, and the satisfactions that comes with it.
Q. CodeChef: What motivates you to compete?
Rajat De: Nothing much, if a contest is interesting I do it. Also if it’s a CodeChef contest I know there are t-shirts as prizes that kind of motivate me.
Additya Popli: The excitement during the contest!
Q. CodeChef: Where do you see yourself 5 years down the line?
Rajat De: 5 year is a long time. I am simply into Competitive Programming because I simply like it. So let’s see what is in the surprise box for me after 5 years.
Additya Popli: Five years down the line, I see myself doing the same I’m doing right now. Solving problems on CodeChef and watching Game of Thrones.
That, ladies & gentlemen is Team dps_dwarka to you. We thoroughly enjoyed their responses and hope you did too.
We will be back soon, so keep watching this space.
Regards,
Rudreshwar
Team CodeChef
Team Name: bandb
Team Members: Nikhil Tadigoppula & Lalit Kundu
Institution/Organization: IIIT-H
SnackDown 2015 Rank: Indian 16
Q. CodeChef: When did you start coding and how did you learn?
Nikhil Tadigoppula: I already knew C++ but barely knew any algorithms. In Class XI when preparing for IOITC, found some IOITC notes online and studied from them. But most learning happened at the training camp itself.
Lalit Kundu: That was my 1st semester of CS undergrad program at IIITH. We have a course called Computer Programming in which language C is taught along with assignments at an online judge in which we have to code implementation problems are few algorithms too. Regarding more serious competitive programming, I started doing a little SPOJ in my second semester and then some told be about CodeChef and I tried my hand at few long contests, but I couldn’t do well. So, I read editorials and learned few algorithms that I didn’t know and started practicing more and more Also, in my second semester we had course called Data Structures and Algorithms where most of the DS and Algos are taught and in labs students are made to implement these algos and DS.
Q. CodeChef: Could you name and share your first programming contest experience?
Nikhil Tadigoppula: My first contest was at IOITC. It was the first time I experienced so much pressure.
Lalit Kundu: If I remember correctly, it was a programming contest by IIT Madras. I had recently started practicing and was doing well, so I formed a team of 3 with my batch mates. It was a short contest and we solved 3 out of 8 problems and were ranked in 60s. We were quite close to the best team of the batch(which had experienced members. It was a thrilling and unique experience. I remember Pradeep George Mathias’ team was at the top in that contest.
Q. CodeChef: How often do you code on any given day & weekend?
Nikhil Tadigoppula: I take breaks from coding once in a while. But when practicing, it is around 2 hours a day. Nothing special for weekends.
Lalit Kundu: Earlier in my second year and first half of 3rd year, I used to give much time irrespective of week days or weekends. It used to be around 2-2.5 hours a day on average. Later, I haven’t been much active and rarely do any contests. I get free on weekends when I am not working at my internship, so I do a little competitive programming and solve 1-2 problems.
Q. CodeChef: What was the biggest hurdle on your road to where you are today?
Nikhil Tadigoppula: IOITC Team Selection Tests. If I hadn’t been selected then, perhaps I might have stopped coding.
Lalit Kundu: It was my inability to concentrate and practice more. Also, not managing time properly. I don’t think I have reached somewhere worthy today, but if I would have practiced and persevered more, I could have been a better competitive programmer today.
Q. CodeChef: What do you think biggest mistake competitive programmers make?
Nikhil Tadigoppula: I repeatedly gave contests without learning anything from them. Perhaps, some others made that mistake too.
Lalit Kundu: Not reading editorials after the contest or not up solving the problems after the contest. Using algorithms as a black box.
Q. CodeChef: What programming language do you use and why?
Nikhil Tadigoppula: I use C++ because it has STL and with other languages there is always a problem of whether it will execute within the time limit because they are slow and even upping the maximum execution time sometimes doesn’t fix it.
Lalit Kundu:C++, because I started with C in my first semester and it was pretty easy to shift to C++. Also, I being very lazy, I didn’t want to learn a new language. And C++ is efficient and fast also.
Q. CodeChef: What advice do you have for other competitive programmers?
Nikhil Tadigoppula: For beginners, I would say it is important to not just code but to also learn from one’s mistakes and try to not repeat them. Also, it is at times not pointless to code for a problem again from the scratch to write cleaner code.
Lalit Kundu: Don’t envy or judge and feel inferior to people based on their ratings. Its just a competition and it doesn’t necessarily mean you have failed at life. Life is much more than competitive programming contests and ratings.
Q. CodeChef: What do you like the most about CodeChef? and what would you don’t like in it?
Nikhil Tadigoppula: The CodeChef rating system is a bit weird. But otherwise, the Long Contest are really what is special about CodeChef.
Lalit Kundu: What I like: Long contests and detailed editorials. What I don’t like: How servers go down tumbling each short contest.
Q. CodeChef: What factors do you believe help you win?
Nikhil Tadigoppula: Luck?
Lalit Kundu: My ability to work as team with my team members. Also, when working individually, I think confidence to solve problems is important.
Q. CodeChef: What motivates you to compete?
Nikhil Tadigoppula: I really enjoy solving a specific type of problems. But they don’t appear very often, so meh.
Lalit Kundu: The thrill of a green tick. The thrill of being on a leaderboard. Also, the thrill of getting goodies.
Q. CodeChef: Where do you see yourself 5 years down the line?
Nikhil Tadigoppula: The standard route. Working for some software company. Unless something nice happens to me.
Lalit Kundu: Working at a software company as a software engineer. Or probably preparing for CAT. Or probably doing PhD. I don’t clearly know yet.
That, ladies & gentlemen is Team bandb to you. We thoroughly enjoyed their responses and hope you did too.
We will be back soon, so keep watching this space.
Regards,
Rudreshwar
Team CodeChef
