  @druceb/

# Dijkstra 2 ## No description

Files
• main.py
main.py
```1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
```
```graph = {'a':{'b':10, 'c':3}, 'b':{'c':1, 'd':2}, 'c':{'b':4,'d':8,'e':2},'d':{'e':7},'e':{'d':9}} #directed weighted graph stored in a dictionary

def dijkstra(graph, start, goal):
shortest_distance = {}
predecessor = {}
unseenNodes = graph
infinity = 99999
path = []

for node in unseenNodes: #set all nodes apart from the starting node to infinity
shortest_distance[node] = infinity
shortest_distance[start] = 0

while unseenNodes:
minNode = None
for node in unseenNodes:
if minNode is None:
minNode = node
elif shortest_distance[node]< shortest_distance[minNode]:
minNode = node

for childNode, weight in graph[minNode].items():
if weight + shortest_distance[minNode] < shortest_distance[childNode]:
shortest_distance[childNode] = weight + shortest_distance[minNode]
predecessor[childNode] = minNode
unseenNodes.pop(minNode)

currentNode = goal
while currentNode != start:
try:
path.insert(0, currentNode)
currentNode = predecessor[currentNode]
except KeyError:
print("Path not Reachable")
break
path.insert(0, start)
if shortest_distance[goal] != infinity:
print("Shortest distance is " + str(shortest_distance[goal]))
print(" and the path is " + str(path))

dijkstra(graph, 'a','d')
```
Fetching token