def dijkstra(graph,start):
start.setDistance(0)
pq =PriorityQueue()
pq.buildHeap([(aVertex.getDistance(),aVertex) for aVertex in graph])
while pq.size() > 0:
currentVert = pq.delMin()
for nextVert in currentVert.getConnections():
newDist = currentVert.getDistance() + currentVert.getWeight(nextVert)
if newDist < nextVert.getDistance():
nextVert.setDistance(newDist)
nextVert.setPred(currentVert)
pq.decreaseKey(nextVert, newDist)
