Broadcasting#
Routines to calculate the broadcast time of certain graphs.
Broadcasting is an information dissemination problem in which a node in a graph, called the originator, must distribute a message to all other nodes by placing a series of calls along the edges of the graph. Once informed, other nodes aid the originator in distributing the message.
The broadcasting must be completed as quickly as possible subject to the following constraints:  Each call requires one unit of time.  A node can only participate in one call per unit of time.  Each call only involves two adjacent nodes: a sender and a receiver.
Return the Broadcast Center of the tree 


Return the Broadcast Time of the tree 