Recently, I started solving codeforces problems from the beginning. I just solved Codeforces Beta Round #8. I couldn't find any tutorial for the round so I decided to write tutorial for the last two problems. The others I solve long time ago in the real contest. Problem E took me quite some time and I couldn't find even a discussion about it, so here are my solutions.
The main observation for this problem is the following: If Alan and/or Bob is at some point X and moves following some curve and travels distance d, then the point at which they finish can be ANY point on or inside the circle with center X and radius d. In other words: If you start at some point X and go to some point Y, you can do this on as long curve as we want(only not shorter then the
All of us use
epsilons in their codes for problems dealing with floating point numbers. Do you have some method of choosing what the value of
epsilon to use or use some fixed number. I just solve an old geometry problem: 8D - Два товарища and when I used
eps = 1e-9 I failed systests, but when I made
eps = 1e-10 my solution passed. This is not the first time I fail because of choosing inappropriate value of
eps and I was wondering if you guys use some methods of choosing the value.
PS: In this problem I mainly use epsilon to write
a < b + esp instead of
a <= b.
Codeforces Beta Round #26 will be held on Monday, the 16th of August, at 19:00 MSK. It will be Codeforces format round, and if all goes well it will be rated. Authors of the problems are Artem Rakhov and me. Thanks to Mike Mirzayanov and Dmitry Matov for help in organizing it. Also thanks to Julia Satushina for translation of problems.
Good luck, see you on the round!
UPD: The contest is over, thank you to everyone for participating.
Wellcome to Codeforces Beta Round #24. I'm author to most of the problems today. Something about me: My name is Nedyalko Prisadnikov and I'm a student from Sofia University in Bulgaria. Here are some pictures of me. Many thanks to Mike Myrzayanov and to Artem Rakhov for organizing the contest, writing alternative solutions and some of the problems.
Good luck and have fun!