def shorted_path(G, src):
dist = {}
pred = {}
n = 0
infinity = sys.maxint
for v in G.keys():
dist[v] = infinity
pred[v] = None
n +=1
dist[src] = 0
bh = BinaryHeap(n, src, infinity)
while not bh.isEmpty():
u = bh.pop()
for v, w in G[u]:
newLen = dist[u] + w
if newLen < dist[v]:
dist[v] = newLen
bh.decreaseKey(v, newLen)
pred[v] = u
return dist, pred
class PriorityQueue:
def __init__(self):
self.queue = BinaryHeap()
# log(n) worst case (both time and space)
def enqueue(self, elem):
self.queue.insert_element(elem)
# log(n) worst case (both time and space)
def dequeue(self):
return self.queue.extract_min()
def peek_min(self):
return self.queue[0]
def isEmpty(self):
return self.queue.isEmpty()
def __str__(self):
return self.queue.__str__()
