Depth First Search and Breath First Search Algorithm http://youtu.be/zLZhSSXAwxI

basic_search_algorithms.py

def dfs(graph, start, result=[]):
    """
    Depth First Search

    Follow each path in depth until
    there are no more unvisted nodes.
    Then reverse until we find an unvisited
    node and continue to the depth of that path.
    Repeat until there are no more unvisted nodes.
    """
    stack = [start]
    while stack:
        value = stack.pop()
        if value not in result:
            result.append(value)
            stack = stack + graph[value]

    return result


def bfs(graph, start, result=[]):
    """
    Breadth First Search

    Visit all children nodes then
    move to next set of unvisted nodes
    and repeat until there are no more
    unvisited nodes.
    """
    stack = [start]
    while stack:
        value = stack.pop(0)
        if value not in result:
            result.append(value)
            stack = stack + graph[value]

    return result


if __name__ == '__main__':
    """
    Call search algorithms.
    Print traversal path.
    """
    graph = {
        'A': ['B', 'D', 'G'],
        'B': ['A', 'E', 'F'],
        'C': ['F', 'H'],
        'D': ['A', 'F'],
        'E': ['B', 'G'],
        'F': ['B', 'C', 'D'],
        'G': ['A', 'E'],
        'H': ['C']
    }

    print 'dfs', dfs(graph, 'A')
    print 'bfs', bfs(graph, 'A')