Lecture 1: Sqrt decomposition, By Sergey Kulik
Lecture 2: Dynamic connectivity problems and their applications, By Sergey Kulik
Lecture 3: Chinese Remainder Theorem, By Praveen Dhinwa
Lecture 4: Introduction of Algebra, By Kevin Charles Atienza
Slides can be found here
Lecture 5: Mobius inversion and related sums, By Kevin Charles Atienza
Slides can be found here
Lecture 1: Aho Corasick algorithm and its applications, By Sergey Kulik
Lecture 2: Biconnectivity and Applications, By Tanuj Khattar
Material can be found at https://tanujkhattar.wordpress.com/2016/01/10/the-bridge-tree-of-a-graph/
Problems to solve:
Lecture 3: Combinatorics, By Kevin Charles Atienza
Slides can be found here
Lecture 4: Geometry, By Kevin Charles Atienza
Slides can be found here
Lecture 1 : Persistence segment tree with its applications and merge sort tree. By Sergey Kulik.
Lecture 2: Fast Fourier Transform and its applications. By Kevin Charles Atienza.
Lecture 3: Max flow with its applications. By Anudeep Nekkanti
List of Problems:
Lecture 4: Zeta Function and its applications to optimizations in dynamic programming. By Arjun Arul.
Lecture 5: Centroid decomposition and use of reflections in some combinatorial problems. By Akashdeep Nain
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
Over 50 days, 13388 teams from 1152 colleges/schools/organizations belonging to 93 countries spread all over the globe and 4 rounds of gruesome online programming battle, later we finally have the finalists of SnackDown 2016. The road to finals for each one of these teams was clad with tough competition from their counterparts yearning for the same. They not only fought them, but also worked hard in different time zones to solve those problems served to them in different rounds of the contest. And with their sheer persistence and application of some fine programming approaches to solve the problems, here they are, standing tall at the gate of SnackDown 2016 Finale.
All of them will put in their heart and souls to win the ultimate title of SnackDown 2016 Champion and we know that. So, while we wait for the finale, let us come together in commemorating their fine achievement and to acknowledge the brilliance of all the teams who participated in the 3rd edition of SnackDown.
Let’s start by giving you the final stats for SnackDown 2016:
The road to the finale was a lot harder than those numbers suggest. Trust us, it was. And here are the brainy geniuses who battled their way into the finals.
We start with the Best Girls Team:
The Best Indian School Team:
The Top 25 Global Teams:
And finally, the Indian Top 25 Teams:
A huge round of applause for all our winners!
Now, as we announced, that top 15 teams from the global and Indian category, along with the all girls team and best Indian school team will be flown down for an all expense trip to the SnackDown 2016 Finale scheduled form 7th – 11th July 2016 at the CodeChef’s headquarters in Mumbai, India. As for the remaining 10 teams from both the categories, they can come at their expense, while their local transport and accommodation will be taken care by us. And should they win the SnackDown 2016, even their onsite travel expense will get reimbursed. This will be the first instance when some of the finest programming brains from all over the globe will be under one roof and we could not be more excited. We are sure you are too. So, while we wait for the competition, we will be sharing some interesting insights into the lives of our finalists in our #KnowYourSnackDownFinalist series of blog posts. So, keep watching this space as we approach towards the finale.
As we put pen down on this post, we would like to congratulate all our winners and participants from SnackDown 2016. We hope you are enjoying the contest.
By the time we reached May Cook-Off 2016, we were only a week away from the start of the SnackDown 2016 qualifier. It meant the COOK70 was the final chance for all the SnackDown aspirants to test their preparations. And the responsibility of provide testing waters to them was taken up by Ke Bi, who made his debut in the shorter format with the contest. And to make him feel at home we had Kevin Charles Atienza as tester. The COOK70 came from a debutant and a seasoned campaigner, so, let’s find out how it went.
We have seen various starts for our Cook-Offs, from disastrous to heavenly. So, we do not go into any contest with a preconceived notion regarding any contest. However, with SnackDown qualifiers just around the corner, we thought that may be the participants will find it easy to cruise through the five problems of Ke Bi. His debutant status in the shorter format also didn’t help in establishing the difficulty level of his problems. So, we left it all on the clock, and waited for it to hit 21:30 Hrs IST. And when it did, it shattered all our notions about the contest, the problem setter, and the participants. Let us tell you how.
Let us start by saying that the problem set from Ke Bi, in more ways than one was reminiscent of that of a seasoned campaigner. If you took part in the contest you will understand what we are talking about. If you did not though, then you must try the problems in our practice section. The contests opened to a flurry of dreaded Red Cross of Wrong Answer on P1Z2S. It made us a tad worried, as we did not get any AC till the first five minutes of the contest. But finally in the seventh minute we had johnathan79717 cracked it, however, he and mmaxio were the only one to receive the green tick of happiness after the first 50 submissions into the contest.
The scarcity of green ticks in the first few hundred submissions raised concerns, especially considering the fact that they were all for P1Z2S, which was supposed to be the easiest of them all. It remained the same way for P1Z2S till the very end of the contest with only 966 successful submissions out of the 5,300 submissions made on it. With accuracy percent of 18.72, P1Z2S, although was the easiest problem of the contest, but certainly not easy enough for everyone to get crack. The other problems were not much of help either for the participants, with Euro remaining devoid of any successful submission. Among the remaining three Easy Numbers saw the highest submissions with 27 AC against it, followed by Maze with 7 and Tandem with 1 AC.
The tough problem set made the journey to the top of the rank table even harder. 3 was the maximum number of problems solved by any user and hence it was obvious that penalties are going to be the deciding factor. And with 0 penalties to his name, uwi took home COOK70. We had all top 6 participants with same number of problem solved, but with different number of penalties and time. And to meet them all, let us take you to the rank table:
The Global Top 10:
Now, the Indian top 10:
Big round of applause for all our winners and for everyone associated with the contest.
Despite the comparatively harder problem set, the participation stats from the contest were rather impressive, and we would let the numbers do the talking here.
Now, we know that you might have faced some difficulty getting past the problems with absolute ease and that you would have immediately devoured the editorials immediately after the contest. But if you did not, then let us take you there.
That will be all from us for now. We hope you enjoyed the post as much as you enjoyed cracking the problems of May Cook-Off 2016. However, if you liked the problems more, then do let us know in the comments section.
With that it’s time to draw curtains on this long delayed tale of May Cook-off and move towards the May LunchTime.
Till next time, adios.
The May Challenge 2016 opened to a huge announcement – start of registrations for SnackDown 2016. The start of summer vacations, just fueled up the excitement, as the students can now solely focus on the job in hand. In May Challenge, we were presenting the participants with their first practice arena before the qualifier. However, we knew that it is the start of summer vacations and not many will want to put their minds to work immediately after the prolonged exam period. But some of them did, so, let’s see how it went.
A familiar problem setting bench featuring Sergey Nagin, Misha Chorniy, Andrii Omelianenko, Vasya Antoniuk, Maksym Bevza, Prateek Gupta, Sergey Kulik, Dmytro Berezin, and Praveen Dhinwa prepared the problems for the contest, which were tested and later had their solutions explained through editorials by Kevin. The translations in Russian, Mandarin, and Vietnamese came from Sergey Kulik, Hu Zecong, and Team VNOI respectively.
The May Challenge 2016 had a rather strong start with anta0 cracking LADDU inside the first 10 minutes of the contest. It made us think that we might be wrong about the impact of summer vacations on the contest. Among the problems that saw early submissions, CHBLLS and LADDU were the easiest of them all, and hence saw the highest submissions into the contest. The rest of the eight problems did not see too many AC submissions against them. It could have been the summer vacations, or it could be the difficulty level of the problems, behind the low number of submissions on the problems. We believe it was the summer vacation, what do you think it was? Do let us know in the comment section.
From the slow and low submission numbers, let us move towards an interesting looking rank table. In our overall rank list of May Challenge 2016, we had five different nations occupying the top five slot. And to tell you who all occupied all the important slots, let us take have a look at all the rank lists.
The prize for women once again remains unclaimed in absence of any women participants in the top 100. So, we move straight towards the men.
The Global Top 10:
The Indian Top 20:
The Global Top 5 School Students:
The Indian Top 5 School Students:
The Global Top 3 Challenge Problem Solvers:
The Indian Top 3 Challenge Problem Solvers:
Let’s give a big round of applause for all our winners.
Now, let’s have a look at the final numbers from the May Challenge 2016.
We hope you all enjoyed the contest, and had a wonderful summer vacations.
Now, before we part ways, it’s customary to give you the editorials from the contest. So, if you have not already gone through them, here are the editorials from MAY16.
That will be all from us for now. We have a lot of catching up to do in our blog department, so we will wrap this post here and will move towards the May Cook-Off 2016. So, while we prepare that, you enjoy this delayed post, share it, and let us know your thoughts on it.
Till next time, adios.
See you at the contests.
Set on the very last day of April, the April LunchTime 2016 well and truly marked the beginning of the happy times for the schools. It was vacation time in institutes all over and the students could not be happier. Everyone had some plan or the other regarding the summers. While, some wanted to get in shape, some just wanted chill on the beaches and mountains. You see, different people, different plans. However, for the programmers, no plan is ever going to be complete without the inclusion of programming contests. So, while you guys prepared your vacation plans, we were busy in squeezing in our programming contests, into your plans without disturbing the original plans too much.
In close quarters with the April LunchTime 2016 was the start of the registrations for our SnackDown 2016, which added to the overall excitement of summer vacations. And set us all on course of a busy summer ahead. And we will tell you all about it, one post at a time. We start with the April LunchTime 2016 set by, Sunny Agarwal and tested by Sergey Kulik.
The 4 problems of LTIME35 saw varying submissions rate, which established their difficulty level in the very initial stage of the contests. While TRICOIN got cracked inside the first 10 minutes of the contest, it took almost an hour and half for the participants to find their way around LABEL. And those two problems were on the totally opposite ends of the difficulty spectrum for the contest. If the numbers are to be taken as an indicator, the former was the easiest one to crack, while the latter one, not so.
Concealed in between the easiest and the hardest were two more problems, which while took some participants up the rank table, for some others, they became the ultimate stop into the contest. With 83 and 7 accepted submissions respectively, COLORING and KSUM weren’t as easy problems as their names suggested they were. But then, they weren’t all that hard as well. The participants, who were patient with them, bettered and cemented their positions on the rank table.
And while we are at it, let’s have a look at the rank table to find out who stood where at the stroke of 22:00 Hrs IST on 30th April 2016:
We start with the ROW top 10:
Now, the Indian top 10:
Congratulations to all our young champions and to everyone associated with the contest!
After the winners, it’s time for the final statistics of the contest. Now, we all have seen better numbers than these, but given that it was just the start of the summer vacations, we wouldn’t mind them low this time around. We are sure; they will go up in coming contest.
We thank you all for joining us in the 35th edition of our LunchTime programming series and hope many more of you to join in the future editions of the contest.
With that we reach at the final stop in the post, where we give you the editorials from the contest and even though we are a tad too late on it, if you haven’t gone through them, check them out now.
And with that we put an end to this tale of April LunchTime 2016. We hope you are having a wonderful time in the ongoing SnackDown 2016 and are enjoying the summers to the maximum. We will be coming soon, with more stories from all the tales of our May contests.
Till then, do let us know your thoughts, opinions, suggestions, and feedback through emails, messages, tweets, or through a pigeon. We love hearing them all.
That will be all from us for now.
Till next time, adios!
See you at the contests!
The second half of April is the fun half. Hot! sure, but fun. The exams are, or about to be gone, the summer vacations have started knocking on the doors, and the planning mode for the summer is on. While the scorching Sun makes the days, lazy and sweaty, the nights bring the solace. Top it with a short exciting programming contest, and you have in your hands night made in programming heaven. And that’s what our April Cook-off 2016 brought.
Set by Constantine Sokol (aka Kostya) and tested contest ready by Pavel Sheftelevich, the five problems of COOK69 had the perfect balance of fun and tease. And it became apparent with the final figures of the contest leaving 1444 submissions on the easiest of the five, and only 10 on the hardest. But that’s just our assumption based on the numbers, you are the real judge of the problem quality, so, do let us know what you thought of them in the comments section below. Meanwhile, let us take you through few of the highlights from the April Cook-Off 2016.
But before that, the final numbers from the contest to put things in perspective:
The smooth start of the contest ensured smooth flow of submissions as well with ODDDIV seeing the most of the early green ticks. Apart from ODDDIV, MOVIEWKN too found the love of the participants in the early stages of the contest. And inside the first 10 minutes of the contest we had almost all probable winners of the contest shining on the rank table. Be it lebron, mgch, alex_2oo8, ceilks, rajat1603 or animesh_f they all were there. And it meant that the battle was on, right from the very start. So, we grabbed our tubs of popcorn and put ourselves for an exciting ride of two and half hours.
And to tell you who stood where on the rank table after that ride, let us give you the names that featured on the final rank list:
We start with the ROW top 10:
Now, we move to the Indian rank table:
With that, it’s now time to give you the editorials for the contest and take your leave. We will be returning soon, with the story of the April LunchTime 2016. But till then, you enjoy these delectable editorials and keep sending your thoughts regarding the contest or any aspect of it.
And now, it’s editorial time:
That will be all from us for now. We hope you enjoyed the post as much as the contest.
We are only 3 days away from the start of online qualifying round for SnackDown 2016. But, while things have gone rather seamless since the registrations opened, there have been few concerns regarding the restrictions on team formation and timing of CodeChef SnackDown 2016 Elimination round. Some serious discussion has been going on our Codeforces’ announcement blog of SnackDown 2016. We too joined in the conversation and tried to reason the restriction, while assuring the possible change in the timings for the online round. So we had a discussion among us and here’s what we have decided:
Reschedule the SnackDown 2016 Elimination Round
Yes, we have rescheduled the Elimination Round and to accommodate it, we also have rescheduled our June Cook-Off 2016. And here are the new timings for both the contests:
SnackDown 2016 Elimination Round:
June Cook-Off 2016:
We hope that the new timings will suit all time zones and that you all are happy with them. If you still have any queries or qualms, do shoot them our way.
Lift restriction on team formation?
Now, this needs a deeper discussion and hence we are leaving this discussion open ended. We have received various arguments in both, for and against, the restriction of team members belonging to the same institutes/organizations. However, while all the arguments have made us think about it, it’s just too short of a time to make any decision now. So, while we are still contemplating the idea of making SnackDown completely open for its future editions, we can not make any commitments at this point.
However, it will be of great help if you all can put forward your thoughts on keeping or lifting the restriction on team formation. Do let us know why do you think it is good/bad to have restriction on team formation? Our reasons we have tried to explain in the same codeforces thread and you can go through them.
On that open ended note, we put an end to this post. We hope we have been clear in communicating the major announcements; however, if you still have any doubts or questions, do let us know. We will be waiting for your thoughts, so pen them down and let us know.
It was “All Fools’ Day” when our April Challenge 2016 began. The air was light all around. The posts and videos featuring hilarious pranks were floating all over social media. So, as the Japanese proverb say ““We’re fools whether we dance or not, so we might as well dance.” We danced. And you danced too. If you don’t remember then let us remind you of chasing the submit button, we even have a wonderful video of it. So, if you ever want to revisit that, you are most welcome. It was fun, wasn’t it?
It was. It was immense fun and giggles to see you all chase that submit button to make your first submission into the contest. And the first one to get hold of it was meintoo. After several attempts of course. He went on to make the first submission into the contest at 03:04 PM and it was an AC. We must say, good job, meintoo. The first problem that saw submission was COLOR, but soon we had our second solved problem in CHBLLNS. To have two solved problems inside the first 10 minutes of the contest is always a pleasing sight and it was no different this time. The contest that started on a fun note, moved further on a fun note, as flurry of submissions started pouring in for COLOR and CHBLLNS. There were few brave hearts who tried their hands on other problems like CHEFPATH and AMAEXPER early into the contest. Some of them got the happiness of green tick, while some others faced the dreaded WA. And so was the start of April Challenge 2016, a little fun and a little anguish.
After the initial rush on the submission table, the flow steadied as the participants moved towards the harder spectrum of the problem set. While, the problems of Sunny Aggarwal (COLOR), Vasia Antoniuk (CHBLLNS), Prateek Gupta (CHEFPATH) and Bipin Baburaj (BIPIN3) made life easy for the early goers into the contest, problem setters Sunny Aggarwal (FIBQ), Roman Furko (FURGRAPH), Aleksandar Abas (AMAEXPER) had different plans with their problems. Their problems turned to be a tad more testing than the earlier problems that the participants had attempted. But not testing enough for the likes of msm1993, ceilks, skyfire, and the likes of them. By the end of the contest we had all the 10 problems cracked, which always is a good sign. And to tell them who topped the table with all 10 solved problems let us take you to the rank table:
We start with the girl’s top 5:
And now we move on to the boy’s category, with global top 10:
The Indian top 20:
The Global top 5 School students:
The Indian top 5 school students:
Now, we move on to the special achievers category to meet the users with highest scores for our challenge problem SNAKGAME:
The top 3 global scorers:
The top 3 Indian scorers:
Big congratulations to all your wonderful people and to everyone associated with April Challenge 2016 for making it such a huge success. Before we move towards the concluding part of the post, here are the final stats for April Challenge 2016:
Now, as we sum up the course of April Challenge 2016 to make sure we would like to take you to the editorials of the contest, for if you have not checked them already and are still scratching your head about SNAKGAME.
That will be all from us regarding April Challenge 2016; we will soon come up with the proceedings of April Cook-Off 2016. Till then, enjoy this post and many others that we have posted recently, and keep sending us your thoughts, messages, and feedback at: email@example.com
Till next time, adios.
See you at the contests.