seminar.py

routes = []
#write a function to find path
def find_path(node, cities, path, distance):
    #add way point
    path.append(node)
    #calcualte path length
    if len(path) > 1:
        distance += cities[path[-2]][node]
    #if path contains all cities and is not a dead end
    #add path from the first city
    if (len(cities) == len(path)) and (path[0]  in cities[path[-1]]):
        global routes
        path.append(path[0])
        distance += cities[path[-2]][path[0]]
        routes.append([distance, path])
    #fork paths for al possible cities not yet used
    for city in cities:
        if(city not in path) and (node in cities[city]):
            find_path(city, dict(cities), list(path), distance)
    

if __name__ == '__main__':
    cities = {
        'RV': {'S': 195, 'UL': 86, 'M': 178, 'BA': 180, 'Z': 91},
        'UL': {'RV': 86, 'S': 107, 'N': 171, 'M': 123},
        'M': {'RV': 178, 'UL': 123, 'N': 170},
        'S': {'RV': 195, 'UL': 107, 'N': 210, 'F': 210, 'MA': 135, 'KA': 64},
        'N': {'S': 210, 'UL': 171, 'M': 170, 'MA': 230, 'F': 230},
        'F': {'N': 230, 'S': 210, 'MA': 85},
        'MA': {'F': 85, 'N': 230, 'S': 135, 'KA': 67},
        'KA': {'MA': 67, 'S': 64, 'BA': 191},
        'BA': {'KA': 191, 'RV': 180, 'Z': 85, 'BE': 91},
        'BE': {'BA': 91, 'Z': 120},
        'Z': {'BA': 120, 'BE': 85, 'RV': 91}
    }
    print('Start city:')
    find_path('RV', cities, [], 0)
    routes.sort()
    if len(routes) != 0:
        print('shortest  route: %s' % routes[0])