hanfang

import collections
import heapq

def shortestPath(edges, source, sink):
    # create a weighted DAG - {node:[(cost,neighbour), ...]}
    graph = collections.defaultdict(list)
    for l, r, c in edges:
        graph[l].append((c,r))
    # create a priority queue and hash set to store visited nodes
    queue, visited = [(0, source, [])], set()