Learn Algorithm Design by Building a Shortest Path Algorithm - Step 49

Tell us what’s happening:

My code would seem to match the syntax, I don’t understand how it keeps raising an unspecified error. Neither my original attempt (commented) nor the list comprehension were successful.

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, target = ''):
    unvisited = list(graph)
    distances = {node: 0 if node == start else float('inf') for node in graph}
    paths = {node: [] for node in graph}
    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]
                if paths[node] and paths[node][-1] == node:
                    paths[node] = paths[current][:]

# User Editable Region

# targets_to_print = [target] if target else graph
targets_to_print = [target if target else graph]

shortest_path(my_graph, 'A')

# User Editable Region

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Challenge Information:

Learn Algorithm Design by Building a Shortest Path Algorithm - Step 49

1 Like

The original attempt is correct, however the indentation should match the original print call that you replaced, so it stays within the function definition.