Learn Algorithm Design by Building a Shortest Path Algorithm - Step 39

Python
1

Tell us what’s happening:

I’m getting the following error: " You should assign distance + distances[current]
to the neighbor node distance inside your new if.

From what I can tell I’m doing the assignment. What else am I missing? Thank you so much for your help.

Your code so far

my_graph = {
    'A': [('B', 3), ('D', 1)],
    'B': [('A', 3), ('C', 4)],
    'C': [('B', 4), ('D', 7)],
    'D': [('A', 1), ('C', 7)]
}

def shortest_path(graph, start):
    unvisited = list(graph)
    distances = {node: 0 if node == start else float('inf') for node in graph}
    paths = {node: [] for node in graph}
    paths[start].append(start)

    while unvisited:
        current = min(unvisited, key=distances.get)
        for node, distance in graph[current]:

/* User Editable Region */

            if distance + distances[current] < distances[node]:
                distances[node] = distance + distances[current]

/* User Editable Region */

     print(f'Unvisited: {unvisited}\nDistances: {distances}\nPaths: {paths}')
    
#shortest_path(my_graph, 'A')

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Challenge Information:

Learn Algorithm Design by Building a Shortest Path Algorithm - Step 39

2

In some way, you have created a syntax error here:

this print statement is indented by five spaces instead of four, making it a syntax error, and the code is not executing, all tests are failing for that reason

1 Like
3

Good grief! I gotta start keeping a better eye on that! Thank you!

4

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