TigerGirl 0 Newbie Poster

Hi
I am trying to find out the complexity class estimate of algorithms. So, the first one is f(100) = 20, f(200) = 76, f(400) = 325, so would that be O(log2 N)? And then f(100) = 100, f(200) = 119, f(400) = 139, and this would be O(1) like similar to constant time?