/** * Unit tests the {@code BellmanFordSP} data type. * * @param args the command-line arguments */ public static void main(String[] args) { In in = new In(args[0]); int s = Integer.parseInt(args[1]); EdgeWeightedDigraph G = new EdgeWeightedDigraph(in); BellmanFordSP sp = new BellmanFordSP(G, s); // print negative cycle if (sp.hasNegativeCycle()) { for (DirectedEdge e : sp.negativeCycle()) StdOut.println(e); } // print shortest paths else { for (int v = 0; v < G.V(); v++) { if (sp.hasPathTo(v)) { StdOut.printf("%d to %d (%5.2f) ", s, v, sp.distTo(v)); for (DirectedEdge e : sp.pathTo(v)) { StdOut.print(e + " "); } StdOut.println(); } else { StdOut.printf("%d to %d no path\n", s, v); } } } }
/** * Reads the currency exchange table from standard input and * prints an arbitrage opportunity to standard output (if one exists). * * @param args the command-line arguments */ public static void main(String[] args) { // V currencies int V = StdIn.readInt(); String[] name = new String[V]; // create complete network EdgeWeightedDigraph G = new EdgeWeightedDigraph(V); for (int v = 0; v < V; v++) { name[v] = StdIn.readString(); for (int w = 0; w < V; w++) { double rate = StdIn.readDouble(); DirectedEdge e = new DirectedEdge(v, w, -Math.log(rate)); G.addEdge(e); } } // find negative cycle BellmanFordSP spt = new BellmanFordSP(G, 0); if (spt.hasNegativeCycle()) { double stake = 1000.0; for (DirectedEdge e : spt.negativeCycle()) { StdOut.printf("%10.5f %s ", stake, name[e.from()]); stake *= Math.exp(-e.weight()); StdOut.printf("= %10.5f %s\n", stake, name[e.to()]); } } else { StdOut.println("No arbitrage opportunity"); } }