// find shortest augmenting path and upate
private void augment()
{
// build residual graph
EdgeWeightedDigraph G = new EdgeWeightedDigraph(2 * N + 2);
int s = 2 * N, t = 2 * N + 1;
for (int i = 0; i < N; i++)
{
if (xy[i] == UNMATCHED)
{
G.AddEdge(new DirectedEdge(s, i, 0.0));
}
}
for (int j = 0; j < N; j++)
{
if (yx[j] == UNMATCHED)
{
G.AddEdge(new DirectedEdge(N + j, t, py[j]));
}
}
for (int i = 0; i < N; i++)
{
for (int j = 0; j < N; j++)
{
if (xy[i] == j)
{
G.AddEdge(new DirectedEdge(N + j, i, 0.0));
}
else
{
G.AddEdge(new DirectedEdge(i, N + j, reducedCost(i, j)));
}
}
}
// compute shortest path from s to every other vertex
DijkstraSP spt = new DijkstraSP(G, s);
// augment along alternating path
foreach (DirectedEdge e in spt.PathTo(t))
{
int i = e.From, j = e.To - N;
if (i < N)
{
xy[i] = j;
yx[j] = i;
}
}
// update dual variables
for (int i = 0; i < N; i++)
{
px[i] += spt.DistTo(i);
}
for (int j = 0; j < N; j++)
{
py[j] += spt.DistTo(N + j);
}
}
public static void MainTest(string[] args)
{
TextInput input = new TextInput(args[0]);
EdgeWeightedDigraph G = new EdgeWeightedDigraph(input);
int s = int.Parse(args[1]);
// compute shortest paths
DijkstraSP sp = new DijkstraSP(G, s);
// print shortest path
for (int t = 0; t < G.V; t++)
{
if (sp.HasPathTo(t))
{
Console.Write("{0} to {1} ({2:F2}) ", s, t, sp.DistTo(t));
foreach (DirectedEdge e in sp.PathTo(t))
{
Console.Write(e + " ");
}
Console.WriteLine();
}
else
{
Console.Write("{0} to {1} no path\n", s, t);
}
}
}