""" 
 count_family_tree.py

 using a family tree graph
 as an example of recursion

    $ python count_family_tree.py 
    The top of the tree is  <Person Mary with kids Sue,Jane,Amy,>
     in countDescendants, looking at  Mary
     in countDescendants, looking at  Sue
     answer for Sue is 1
     in countDescendants, looking at  Jane
     in countDescendants, looking at  Sarah
     answer for Sarah is 1
     in countDescendants, looking at  Betty
     answer for Betty is 1
     answer for Jane is 3
     in countDescendants, looking at  Amy
     answer for Amy is 1
     answer for Mary is 6
    total number of people is  6
 
 Jim M | Nov 2013 | MIT License
"""

class Person(object):
    def __init__(self, name):
        self.name = name
        self.kids = []
    def addKid(self, kid):
        self.kids.append(kid)
    def __str__(self):
        kids_names = ""
        for kid in self.kids:
            kids_names = kids_names + kid.name + ","
        return "<Person {} with kids {}>".format(
            self.name, kids_names)

def makeTree():
    """ Make the family tree that Jim put on the board"""
    mary = Person("Mary")
    for childname in ['Sue', 'Jane', 'Amy']:
        mary.addKid(Person(childname))
    jane = mary.kids[1]
    for childname in ['Sarah', 'Betty']:
        jane.addKid(Person(childname))
    return mary

def countDescendants(person):
    """ Return count of this person and descendants,
        i.d. 1 + number of children and children of children
        etc for this person """
    print " in countDescendants, looking at ", person.name
    count = 1    # this person
    for kid in person.kids:
        count = count + countDescendants(kid)
    print " answer for {} is {}".format(person.name, count)
    return count

def main():
    root = makeTree()
    print "The top of the tree is ", str(root)
    totalPeopleCount = countDescendants(root)
    print "total number of people is ", totalPeopleCount

main()