def dijkstra(agraph, start):
pq = PriorityQueue()
start.setdistance(0)
pq.buildheap([(v.getdistance(), v) for v in agraph])
while not pq.isEmpty():
currentvert = pq.delmin()
for nextvert in currentvert.get_connections():
newdist = currentvert.getdistance() + currentvert.get_weight(
nextvert)
if newdist < nextvert.getdistance():
nextvert.setdistance(newdist)
nextvert.setpred(currentvert)
pq.decreasekey(newvert, newdist)
