While I was trying to solve a problem that given a network of people prove that any two people are separated by a distance of 6 or less. I tried pondering on any sub-quadratic solution by finding maximum shortest distance in a graph. Are there any common know methods to find diameter of graph?








I'm pretty sure that in general graph you cannot do better than $$$O(N^2)$$$. Someone please correct me if I am wrong.
Can you please suggest some source to read about it ?