/**
* Unit tests the {@code FordFulkerson} data type.
*
* @param args the command-line arguments
*/
public static void main(String[] args) {
// create flow network with V vertices and E edges
int V = Integer.parseInt(args[0]);
int E = Integer.parseInt(args[1]);
int s = 0, t = V-1;
FlowNetwork G = new FlowNetwork(V, E);
StdOut.println(G);
// compute maximum flow and minimum cut
FordFulkerson maxflow = new FordFulkerson(G, s, t);
StdOut.println("Max flow from " + s + " to " + t);
for (int v = 0; v < G.V(); v++) {
for (FlowEdge e : G.adj(v)) {
if ((v == e.from()) && e.flow() > 0)
StdOut.println(" " + e);
}
}
// print min-cut
StdOut.print("Min cut: ");
for (int v = 0; v < G.V(); v++) {
if (maxflow.inCut(v)) StdOut.print(v + " ");
}
StdOut.println();
StdOut.println("Max flow value = " + maxflow.value());
}
/**
* Checks optimality conditions.
*
* @param G the edge-weighted graph
* @return {@code true} if optimality conditions are fine
*/
private boolean check(EdgeWeightedGraph G) {
// compute min st-cut for all pairs s and t
// shortcut: s must appear on one side of global mincut,
// so it suffices to try all pairs s-v for some fixed s
double value = Double.POSITIVE_INFINITY;
for (int s = 0, t = 1; t < G.V(); t++) {
FlowNetwork F = new FlowNetwork(G.V());
for (Edge e : G.edges()) {
int v = e.either(), w = e.other(v);
F.addEdge(new FlowEdge(v, w, e.weight()));
F.addEdge(new FlowEdge(w, v, e.weight()));
}
FordFulkerson maxflow = new FordFulkerson(F, s, t);
value = Math.min(value, maxflow.value());
}
if (Math.abs(weight - value) > FLOATING_POINT_EPSILON) {
System.err.println("Min cut weight = " + weight + " , max flow value = " + value);
return false;
}
return true;
}