def dijkstra(self, graph, source):
"""Dijkstra
This method computes shortest distance and path for each node
from the source node, and save results in each node's distance
attribute.
return None
"""
reachable = self.preprocessing(graph, source)
self.dists[source.id] = 0
self.paths[source.id] = source.id
unknown = HashHeap(
key=lambda x, y: self.dists[x.id] < self.dists[y.id])
for node_id in reachable:
unknown.add(graph[node_id]) # add to unknown
marked = [False] * len(graph)
while unknown:
node = unknown.pop()
marked[node.id] = True
for edge in node.edges:
adj = graph[edge.head]
if (not marked[adj.id] and
self.dists[node.id] + edge.dist < self.dists[adj.id]):
self.dists[adj.id] = self.dists[node.id] + edge.dist
unknown.update(adj) # method only in hash heap
self.paths[adj.id] = node.id