# Code from Chapter 16 of Machine Learning: An Algorithmic Perspective (2nd Edition)
# by Stephen Marsland (http://stephenmonika.net)

# You are free to use, change, or redistribute the code in any way you wish for
# non-commercial purposes, but please maintain the name of the original author.
# This code comes with no warranty of any kind.

# Stephen Marsland, 2008, 2014

def findPath(graph, start, end, pathSoFar):
    pathSoFar = pathSoFar + [start]
    if start == end:
        return pathSoFar
    if start not in graph:
        return None
    for node in graph[start]:
        if node not in pathSoFar:
            newpath = findPath(graph, node, end, pathSoFar)
            return newpath
    return None

graph = {'A': ['B', 'C'],'B': ['C', 'D'],'C': ['D'],'D': ['C'],'E': ['F'],'F': ['C']}
print findPath(graph,'A','D',[])