/// <summary>
/// Determines whether the edge-weighted digraph <c>G</c> has a topological
/// order and, if so, finds such an order.</summary>
/// <param name="G">the edge-weighted digraph</param>
///
public Topological(EdgeWeightedDigraph G)
{
EdgeWeightedDirectedCycle finder = new EdgeWeightedDirectedCycle(G);
if (!finder.HasCycle)
{
DepthFirstOrder dfs = new DepthFirstOrder(G);
order = dfs.ReversePost();
}
}
private int[] rank; // rank[v] = position of vertex v in topological order
/// <summary>
/// Determines whether the digraph <c>G</c> has a topological order and, if so,
/// finds such a topological order.</summary>
/// <param name="G">the digraph</param>
///
public Topological(Digraph G)
{
DirectedCycle finder = new DirectedCycle(G);
if (!finder.HasCycle)
{
DepthFirstOrder dfs = new DepthFirstOrder(G);
order = dfs.ReversePost();
rank = new int[G.V];
int i = 0;
foreach (int v in order)
{
rank[v] = i++;
}
}
}
private int count; // number of strongly-connected components
/// <summary>Computes the strong components of the digraph <c>G</c>.</summary>
/// <param name="G">the digraph</param>
///
public KosarajuSharirSCC(Digraph G)
{
// compute reverse postorder of reverse graph
DepthFirstOrder dfs = new DepthFirstOrder(G.Reverse());
// run DFS on G, using reverse postorder to guide calculation
marked = new bool[G.V];
id = new int[G.V];
foreach (int v in dfs.ReversePost())
{
if (!marked[v])
{
this.dfs(G, v);
count++;
}
}
// check that id[] gives strong components
Debug.Assert(check(G));
}
public static void MainTest(string[] args)
{
// read in digraph from command-line argument
TextInput input = new TextInput(args[0]);
Digraph G = new Digraph(input);
DepthFirstOrder dfs = new DepthFirstOrder(G);
Console.WriteLine(" v pre post");
Console.WriteLine("--------------");
for (int v = 0; v < G.V; v++)
{
Console.Write("{0,4} {1,4:} {2,4}\n", v, dfs.Pre(v), dfs.Post(v));
}
Console.Write("Preorder: ");
foreach (int v in dfs.Pre())
{
Console.Write(v + " ");
}
Console.WriteLine();
Console.Write("Postorder: ");
foreach (int v in dfs.Post())
{
Console.Write(v + " ");
}
Console.WriteLine();
Console.Write("Reverse postorder: ");
foreach (int v in dfs.ReversePost())
{
Console.Write(v + " ");
}
Console.WriteLine();
}
