valid_route.py

# Enter your code here. Read input from STDIN. Print output to STDOUT
import copy

all_valid_routes = {
    'A': ['AB', ],
    'B': ['BC', 'BC', 'BC', 'BD', 'BD', 'BA'],
    'C': ['CD', 'CD', 'CD', 'CB', 'CB', 'CB'],
    'D': ['DE', 'DC', 'DC', 'DC', 'DB', 'DB'],
    'E': ['ED'],
}


def check_for_valid_routes(string):
    valid_routes = copy.deepcopy(all_valid_routes)
    string_length = len(string)

    is_valid = True
    path_count = 0

    for i in range(string_length):
        starting_node = string[i]
        edge = string[i: i+2]
        reverse_edge = edge[::-1]
        ending_node = reverse_edge[0]

        available_valid_path = valid_routes[starting_node]
        if len(edge) > 1:
            if edge in available_valid_path:
                path_count += 1
                _ = available_valid_path.pop(available_valid_path.index(edge))
                valid_routes[starting_node] = available_valid_path
                if reverse_edge in valid_routes[ending_node]:
                    available_valid_path = valid_routes[ending_node]
                    _ = available_valid_path.pop(
                        available_valid_path.index(reverse_edge))
                    valid_routes[ending_node] = available_valid_path
            else:
                is_valid = False

    print(is_valid)
    print(path_count)


if __name__ == '__main__':
    string = input()
    check_for_valid_routes(string)