Learn Algorithm Design by Building a Shortest Path Algorithm - Step 54

Python
1

Tell us what’s happening:

Describe your issue in detail here.

What am I doing wrong? I have tried removing the target entirely and putting ‘F’ only but didn’t work. Also tried the hint " You should call shortest_path passing my_graph , 'A' and 'F' as the arguments." but it didn’t work nor got an output…

Your code so far


# User Editable Region

my_graph = {
    'A': [('B', 5), ('C', 3), ('E', 11)],
    'B': [('A', 5), ('C', 1), ('F', 2)],
    'C': [('A', 3), ('B', 1), ('D', 1), ('E', 5)],
    'D': [('C',1 ), ('E', 9), ('F', 3)],
    'E': [('A', 11), ('C', 5), ('D', 9)],
    'F': [('B', 2), ('D', 3)]
}

def shortest_path(graph, start, target = 'F'):
    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]
                if paths[node] and paths[node][-1] == node:
                    paths[node] = paths[current][:]
                else:
                    paths[node].extend(paths[current])
                paths[node].append(node)
        unvisited.remove(current)
    
    targets_to_print = [target] if target else graph
    for node in targets_to_print:
        if node == start:
            continue
        print(f'\n{start}-{node} distance: {distances[node]}\nPath: {" -> ".join(paths[node])}')
    
    return distances, paths
    
shortest_path(my_graph, 'A')

# User Editable Region

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Challenge Information:

Learn Algorithm Design by Building a Shortest Path Algorithm - Step 54

2

You appear to have created this post without editing the template. Please edit your post to Tell us what’s happening in your own words.

3

Hi @ChrisKonto

You need to pass the string mentioned in the instructions as the third argument in the function call.

Happy coding

4

from what I understood I did this
def shortest_path(graph, start, ‘F’):
but it’s still wrong and I had already tried it before. You just told me what the step is asking with other words, that did not help at all.

5

This is exactly how to help someone understand the instructions

1 Like
6

You have added F as the default parameter in the function definition. When you call your function you still only passed 2 arguments

7

I don’t understand how is this not an argument… specifying the function name, followed by the function call operator and any data values the function expects to receive . Is what I find online for how to make an argument and thats what I also know. So how exactly is that wrong?

8

Hi @ChrisKonto

You modified the function definition, line 10.

The instructions ask you to modify the function call, line 36.

Happy coding

9

The instructions are

modify your function call passing F as the third argument and check the output.

Which is your function call?

1 Like
10

Oh alright, I understood thank you! I thought it was speaking about the def

1 Like
11

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