def applyDijkstra(g, start, finish):
"""
Applies Dijkstra's algorithm to the graph g, updating the
distance from start to each node in g.
"""
#MAKE SURE THAT THE ALGORITHM IS APPLIED ONLY TO THE START/FINISH NODE
#USE node.predecessor, node.distance
#initializeSingleSource(g, start)
finalized = set()
frontier = PriorityQueue()
finishedendnode = False
#explored = set()
start.distance = 0
start.predecessor = None
frontier.enqueue(start)
while not frontier.isEmpty() and finishedendnode == False:
node = frontier.dequeue()
#print(type(node))
finalized.add(node)
if node == finish:
finishedendnode = True
break
for arc in node.getArcsFrom():
n1 = arc.getStart()
n2 = arc.getFinish()
#print("n1: "+ str(n1))
#print("n2: "+ str(n2))
#print("node: "+ str(node))
if n2 not in finalized:
#print("n2: "+ str(n2))
if n2 not in frontier:
initIndivNode(n1, n2, arc)
frontier.enqueue(n2, n2.distance)
#init single source
else:
oldDistance = n2.distance
relax(n1, n2, arc.getCost())
if n2.distance < oldDistance:
frontier.raisePriority(n2, n2.distance)
def applyDijkstra(g, start, finish=None):
"""
Applies Dijkstra's algorithm to the graph g, updating the
distance from start to each node in g.
"""
initializeSingleSource(g, start)
finalized = set()
pq = PriorityQueue()
pq.enqueue(start)
while not pq.isEmpty():
node = pq.dequeue()
finalized.add(start)
if node == finish: #if we are at the finish node then we are all done!
break
for arc in node.getArcsFrom():
n1 = arc.getStart()
n2 = arc.getFinish()
if n2 not in finalized:
if n2.distance is math.inf: #check if the node is one that we have not visited before, in which case we will add it to the queue
pq.enqueue(n2)
oldDistance = n2.distance
relax(n1, n2, arc.getCost())
if n2.distance < oldDistance:
pq.raisePriority(n2, n2.distance)