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### bernett's blog

By bernett, 9 years ago,

Hello everyone, I wanted to know if there is a way to hide the problem tags section in a problem's page. Whenever I go to a problem's page for practicing, most of the time I look into the problem tag section accidentally which tells whether the problem is DP or greedy or graph,etc. And then I only think of solving the problem in that way. But, this is not the case during contests, since we have to breakdown the problem and find out if it is DP or greedy,etc. So, I want to practice in finding what kind of problem it is, and not knowing what approach to use to solve the problem before even reading the question sometimes. So, is there any possible way to do this?

• +1

By bernett, 10 years ago,

Hello everyone, I have been thinking about this problem http://codeforces.com/contest/452/problem/F for quite some time and finally couldnt come up with anything. Then I saw this solution to the problem http://codeforces.com/contest/452/submission/7280377 . What I could get from his solution is, it is assumed that the middle value and one of the numbers a or b is within a range of 5. Could someone please explain how this approach works and its proof. Also correct me if my assumption about his solution is wrong.

• +21

By bernett, 10 years ago,

Hello everyone, Today I stumbled upon a new topic called Möbius Function and i read about it both in the wiki as well as in one of the codechef editorials page. This is the problem http://www.codechef.com/problems/COPRIME3 and here is its editorial http://discuss.codechef.com/questions/46074/coprime3-editorial .

Even after i read through the editorial i still couldn't understand why the solution for this problem using Möbius function is correct and its proof. So, can anyone please give a simple explanation about the Möbius function and the various kinds of problems that can be solved with it?

• +14