code Dijkstra's Algorithm for a directed graph

example graph.txt:

0 (1,3) (3,5) 1 (2,6) 2 (4,2) 3 (1,1) (2,4) (4,6) 4 (0,3) (2,7)

example dist.txt:

0 1 2 3 4 0 8 9 5 7

using a priority queue implemented as a heap. Input is from a file "graph.txt" which contains adjacency lists. Format of the file will be discussed in class. Source vertex is the first vertex in the list. Output is to the file "dist.txt" which contains the array of shortest paths weights.