Learn Algorithm Design by Building a Shortest Path Algorithm - Step 42

Tell us what’s happening:

perhaps my syntax with extend() is wrong?

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

/* User Editable Region */

                if paths[node][-1] == node:
                    paths[node] = paths[current]
                else:
                    paths[node].extend(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 42

How do you access the current node path? You’ve done this already in the previous line

1 Like

Hello! @lswoboda051

You’re almost there!

The else condition needs to be modified (paths[current]) must be the argument inside the extend() function.

1 Like

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