public static void main(String[] args) {

        // create random DAG with V vertices and E edges; then add F random edges
        int V = Integer.parseInt(args[0]);
        int E = Integer.parseInt(args[1]);
        int F = Integer.parseInt(args[2]);
        EdgeWeightedDigraph G = new EdgeWeightedDigraph(V);
        int[] vertices = new int[V];
        for (int i = 0; i < V; i++) vertices[i] = i;
        StdRandom.shuffle(vertices);
        for (int i = 0; i < E; i++) {
            int v, w;
            do {
                v = StdRandom.uniform(V);
                w = StdRandom.uniform(V);
            } while (v >= w);
            double weight = Math.random();
            G.addEdge(new DirectedEdge(v, w, weight));
        }

        // add F extra edges
        for (int i = 0; i < F; i++) {
            int v = (int) (Math.random() * V);
            int w = (int) (Math.random() * V);
            double weight = Math.random();
            G.addEdge(new DirectedEdge(v, w, weight));
        }

        StdOut.println(G);

        // find a directed cycle
        EdgeWeightedDirectedCycle finder = new EdgeWeightedDirectedCycle(G);
        if (finder.hasCycle()) {
            StdOut.print("Cycle: ");
            for (DirectedEdge e : finder.cycle()) {
                StdOut.print(e + " ");
            }
            StdOut.println();
        }

        // or give topologial sort
        else {
            StdOut.println("No directed cycle");
        }
    }