Originally Posted by

**peaz9482** There is a group of 30 people who communicate only by phone. During any one to one phone conversation the two members exchange **all** their information. Find the number of calls needed so that everyone finds out every bit of news.

Thanks for any help you can give me!!

Interesting.

I recommend starting with smaller networks first to try to get a handle. For example, with four people, you can think of four binary numbers between 0000 and 1111 representing the state of each person's knowledge, and the following scenario can happen

Code:

0001 0010 0100 1000
0011 0011 0100 1000
0011 0011 1100 1100
0011 1111 1111 1100
1111 1111 1111 1111

I don't know the solution to your problem, but already the above example provides a feel for what an optimal calling sequence (algorithm) might be.