for each u in V:
key[u] = infinity // cost array
pi[u] = infinity // from array
Q = new PriorityQueue(V)
key[root] = 0
while Q is not empty:
u = extractMin(Q)
# Reduce nodes
for v in adj[u]:
if v in Q and w[u,v] < key[v]:
key[v] = w[u,v]
Analysis
Priority queue is slower than array when the graph is dense, so sometimes it's better to use Dijsktra's algorithm.