public static void dijkstra_function(graph G, int s, int no)
throws IOException { // s is the index of the starting vertex
// declare variables
int nVerts, u, v;
int[] dist;
nVerts = G.vertices(); // get number of vertices in the graph class
// initialize array
dist = new int[nVerts];
Stack[] path = new Stack[nVerts];
for (v = 0; v < nVerts; v++) // initializations
{
dist[v] = 99999; // 99999 represents infinity
path[v] = new Stack<Integer>();
path[v].push(s);
} // end for
dist[s] = 0;
PriorityQueue Q = new PriorityQueue(dist);
while (Q.Empty() == 0) // if heap is not empty
{
u = Q.Delete_root();
v = G.nextneighbor(u);
while (v != -1) // for each neighbor of u
{
if (dist[v] > dist[u] + G.edgeLength(u, v)) {
dist[v] = dist[u] + G.edgeLength(u, v);
path[v].pop();
path[v].push(u);
Q.Update(v, dist[v]);
}
v = G.nextneighbor(u); // get the next neighbor of u
} // end while
} // end while
for (v = 0; v < nVerts; v++) // initializations
{
while ((Integer) path[v].peek() != s) {
int top = (Integer) path[v].peek();
for (int i = 0; i < path[top].size(); i++) {
path[v].push(path[top].get(i));
}
}
}
FileWriter fw = new FileWriter("path" + no + ".txt");
for (int i = 0; i < nVerts; i++) {
fw.write(dist[i] + " ");
while (!path[i].empty()) fw.write((Integer) path[i].pop() + " ");
fw.write(i + "\n");
} // end for
fw.close();
} // end bfs_function
