"""
 recursive graph

 in class Nov 13
"""

class GraphNode(object):
    """ A node in a tree """

    def __init__(self, name=""):
        self.name = name
        self.friends = []
        self.counted = False
    
    def __str__(self):
        result = "GraphNode(" + self.name + ": "
        for friend in self.friends:
            result += " " + self.friend.name
        return result + ")"

    def befriends(self, friend):
        self.friends.append(friend)
        # We can't recursively call friend.befriends(self)
        # here, because that would be "friends forever"
        # which would exceed the recursion limit.
        friend.friends.append(self)

    def network_size(self):
        size = 1   # me
        self.counted = True
        for friend in self.friends:
            # Oops: infinite recursion
            #size += friend.network_size()
            if not friend.counted:
                size += friend.network_size()
        return size

n = GraphNode('n')
m = GraphNode('m')
p = GraphNode('p')
q = GraphNode('q')
n.befriends(m)
n.befriends(p)
p.befriends(q)
q.befriends(n)

def main():
    size = n.network_size()
    print "size of network is", size
    

if __name__ == "__main__":
    main()