Displaying the full path from A to E

The shortest_distances variable contains the following data at the end of the shortest_path function:

{
    'A': (0, 'A'), 
    'B': (10, 'A'), 
    'C': (30, 'B'), 
    'D': (35, 'A'), 
    'E': (36, 'C')
}

We can use this information to nicely display the full path between A and E. Starting from the end node, E, shortest_distances["E"][1] contains the previous node in the shortest path. Similarly, shortest_distances["C"][1] contains the previous node in the shortest path from A to E and so on.

We can write the following function to retrieve each node and distance in the path:

def nice_path(start_node, end_node, shortest_distances):
    node = end_node
    result = []
    while node != start_node:
        result.append((node, shortest_distances[node][0]))
        node = shortest_distances[node][1]
    result.append((start_node, 0)...