Suppose there are $n$ people and all of them have unique information. In one round, two people can interact and tell each other all information they know. In total, how many round may be required so that everyone knows all $n$ pieces of information?
I could not prove it but after going over some examples $n = 4, 5, 6, 8$, I found it to obey $f(n) = 2\cdot n - 4$, but I dont know if this is the minimum. How can we find minimum number?