Hi all!
My name is Alexey Dergunov, and I'm glad to present you the first "violet" Codeforces round. I hope the problems will not seem so "violet" to you :)
Many thanks to following people who helped me a lot with contest preparation:
- MikeMirzayanov (Mikhail Mirzayanov)
- RAD (Artem Rakhov)
- Connector (Makar Krasnoperov)
- anonymous (Anonymous)
- Delinur (Maria Belova)
UPD. Contest is over, and we know the winners!
Division 1:
Division 2:
- 1st place - pmnox
- 2nd place - muliguishou
- 3rd place - craus
UPD 2. Analysis: http://codeforces.net/blog/entry/2208 (English version is not full yet...)
I hope that the system tests and rating process is faster than the previous one :)Good Luck :)Regarding the problems, on div 2 problem C, I think the pretests were "too hard". Since codeforces allows for hacking of fellow competitors' solutions, you could have left some of those out of the pretests. I believe it was almost impossible to hack a solution that passed them.
I don't understand what are such problems doing in programming contests.
It happens when the author is afraid that the problems may be too easy for someone and the only goal is to make contestants spend more time. This is not what programming contest problems should be.
I haven't read B and C because they looked ugly without reading them. Maybe I missed some great problems but what I've read and solved isn't what I enjoy in contests.
So upset!!My english is very poor.I can't understand the meaning of "there are no either three pairwise acquainted or three pairwise unacquainted people" !
Let 1,2,3 are three friend.
Either all pairs (1,2), (2,3), (1,3) are acquainted each other or all pairs are unacquainted each other.
Actually, at first I can guess the meaning and my program is correct,but I always get wrong answer on pretext 2.So I focus on what is the meaning of this sentence.After the contest , I find out that I'm so careless,I print "FALL" instead of "FAIL".So careless I am!!!!
Use the recursive inclusion/exclusion as in similar problems and use memoization for small values.
This problem was too boring for Div1-E as well.
Select 7,8,10,11 and 6,9.