/* BreadthFirst: breadth-first traversal of a graph.

 
Pre:  The graph G has been created.
Post: The function Visit has been performed at each vertex of G, where
the vertices are chosen in breadth-first order.
Uses: Queue functions.
 */
void BreadthFirst(Graph G, void (*Visit)(Vertex))
{
    Queue Q;        /* QueueEntry defined to be Vertex. */
    Boolean visited[MAXVERTEX];
    Vertex v, w;

    for (all v in G)
        visited[v] = FALSE;
    CreateQueue(Q);

    for (all v in G)
        if (!visited[v]) {
            Append(v, Q);

            do {
                Serve(v,Q);
                if (!visited[v]) {
                    visited[v] = TRUE;
                    Visit(v);
                }

                for (all w adjacent to v)
                    if (!visited[w])
                        Append(w, Q);
            } while (!QueueEmpty(Q));
        }
}