### Tell us what’s happening:

Describe your issue in detail here.

Trying to add an additional condition to the nested `if`

statement to ensure that `paths[node]`

is non-empty before accessing `paths[node][-1]`

.

### 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]
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)
print(f'Unvisited: {unvisited}\nDistances: {distances}\nPaths: {paths}')
```

#shortest_path(my_graph, ‘A’)

```
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] != [] and paths[node][-1] == node:
paths[node] = paths[current]
# User Editable Region
else:
paths[node].extend(paths[current])
paths[node].append(node)
unvisited.remove(current)
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 45