public void Run()
{
// create random DAG with V vertices and E edges; then add F random edges
const int vv = 50;
const int e = 100;
const int f = 20;
var digraph = new EdgeWeightedDigraph(vv);
var vertices = new int[vv];
for (var i = 0; i < vv; i++)
{
vertices[i] = i;
}
StdRandom.Shuffle(vertices);
for (var i = 0; i < e; i++)
{
int v, w;
do
{
v = StdRandom.Uniform(vv);
w = StdRandom.Uniform(vv);
} while (v >= w);
var weight = StdRandom.Uniform();
digraph.AddEdge(new DirectedEdge(v, w, weight));
}
// add F extra edges
for (var i = 0; i < f; i++)
{
var v = StdRandom.Uniform(vv);
var w = StdRandom.Uniform(vv);
var weight = StdRandom.Uniform(0.0, 1.0);
digraph.AddEdge(new DirectedEdge(v, w, weight));
}
Console.WriteLine(digraph);
// find a directed cycle
var finder = new EdgeWeightedDirectedCycle(digraph);
if (finder.HasCycle())
{
Console.Write("Cycle: ");
foreach (var edge in finder.Cycle())
{
Console.Write(edge + " ");
}
Console.WriteLine();
}
// or give topologial sort
else
{
Console.WriteLine("No directed cycle");
}
Console.ReadLine();
}
// by finding a cycle in predecessor graph
private void findNegativeCycle()
{
int V = edgeTo.Length;
EdgeWeightedDigraph spt = new EdgeWeightedDigraph(V);
for (int v = 0; v < V; v++)
if (edgeTo[v] != null)
spt.addEdge(edgeTo[v]);
EdgeWeightedDirectedCycle finder = new EdgeWeightedDirectedCycle(spt);
cycle = finder.Cycle();
}