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)
def prim(g, start):
pq = PriorityQueue()
for v in g:
v.setPred(None)
v.setdistance(sys.maxsize)
start.setdistance(0)
pq = buildheap([(v.getdistance(), v) for v in g])
while not pq.isEmpty():
currentvert = pq.delmin()
for nextvert in currentvert.get_connections():
newcost = currentvert.get_weight(nextvert)
if nextvert in pq and newcost < nextvert.getdistance():
nextvert.setpred(currentvert)
nextvert.setdistance(newcost)
pq.decreasekey(nextvert, newcost)
