Hi!
Ad Infinitum is back with Infinitum September'14, a monthly contest restricted to mathematics domain, held on HackerRank.
Register at https://www.hackerrank.com/infinitum-sep14
The contest commences on 19th September 15:30 UTC. You are allowed to enter the contest anytime, for tie breaking the timer will start when you view the first challenge, which allows you to start late at your convenience, but once started try to finish as fast as possible to be on top of the leaderboard :)
It's a 2 days contest with 8 problems (3 Easy, 3 Medium, 2 Hard)
Scoring Distribution: 20 25 30 40 60 80 100 120
Top 10 on leaderboard gets Cool HackerRank T shirt,
Contributers
kevinsogo
tmt514
sevenkplus
darkshadows
ssrsinghrajput
amitp08
aka_007
ikbal
oversolver
Detailed editorials will be available by the end of contest :) I suggest you to try all challenges and at the end of contest understand the solutions.
GL&HF
Uh, 475pts, uwi beaten, it's 3:45 AM, I can go to bed now x_x. I liked "Farmer" and "Kevin and Expected Value" problems the most. "Geometry queries" was also fun for me, but 2 years ago, now it was rather standard stuff to me.
Moreover I conclude that "Math" from title has wide meaning. I don't feel that computational geos and Farmer were strongly connected (pun intended? — for those who read all the problems) with math, though indeed some problems can be given only in a contest with a warning word "Math" :P.
475 points, Swistakk beaten, it's 3 AM, I can go to bed now x_x.
I agree that the computational geometry felt a bit out of place, especially something like the query problem. The farmer problem was also a bit far away from math, but it was nice so I don't mind :P
I liked Kevin and Expected Value the most, in part because I had to spend more than half an hour debugging my farmer code -.-'
Gratz :P. Though in this particular contest, according to leaderboard beating me was harder than beating uwi, I guess that in general it is definitely the other way around :D.
Btw is 0,5h of debugging much to you? I have to say that I was extremely lucky to code both Farmer and Geometry Queries without any bugs, they were working just after compiling, which was very surprising especially for queries problem, but my queries got TLEs and I spent few hours on working this out and it turned out that mere changing long doubles to doubles was sufficient :( (I hope that I'm not spoling anything :D).
Moreover, I submitted problems about divisors and it had been processing for 2 minutes and I got 1 WA on #2 test, 28.64/30 pts. I spent something like 0,5-1h finding bug and it turned out that this WA was due to server's error, I resubmitted exactly the same code and got AC :/.
I have made a note of your Same code WA/AC bug and team will try to fix that soon.
It's a very bad bug and in future if you ever encounter that contact me ASAP.
why would they give the highest number of points to a problem with a ready formula?
I think the formula is far from `ready'.
I'm sorry but you're wrong.
That is exactly the way I solved it: I googled the article where the first page of the preview had even two formulas on it.
I googled 3 papers, and first two of them were both with wrong formulas :D
One don't worked at all, second worked only for n<=4 :)
Can you put a link of the correct paper here please? I found one paper but only ambiguous pseudo code was provided in it.
Here it is.
Algorithm to find which I used during contest:
1. Google "The number of strong digraphs"
2. Click on the second link.
It was even provided in the statement in some sense. There was a link to that sequence on OEIS given and there was a paper with ready formulas using generating functions and that's how I've "solved" it. I don't have a slightest idea why my code does something related to strong digraphs in any sense, there was even a natural logarithm of generating function included in those formulas :D.
Maybe you'll add some "start contest" key instead of simply allowing anyone to read problems and starting timer at moment when they open problemset?:)
I was not registering for contest until a moment when i want to start it, because i know that i may visit https://www.hackerrank.com/contests while upsolving some old problems and it will automatically open this contest as active and start timer for me. I thought that it is enough. But yesterday i received message "can you help me with a problem some_link_here". I opened this link without even looking at adress, and it turned out that it's one of easy problems from ongoing Ad Infinitum:) And i was not even registered for it at that moment:) I thought that it may start timer for me, but i had no time to solve contest yesterday anyway, so i just closed it.
And when i registered for contest today and started solving it, I received 1067 minutes of penalty for first problem — then i understood that timer really started when i opened one of problems yesterday:)
Maybe you'll change it in some way, so that we'll see problems/leaderboard only after pressing some "start contest!" button, and we'll be free to visit hackerrank without risk to start a contest unintentionally.
Please even once vote up my comment ! I'd be happy.
LOL! I did.
What about T-shirts? I placed in TOP10 both in September and October and I wasn't contacted by organizers or anybody else in that matter yet.
I am aware of that, there was some changes in the management internally and hence the delay. I promise you'll get confirmation email by monday for both the T shirts :)