/// <summary>
/// depth first search preorder and postorder in a digraph
/// </summary>
/// <param name="g"></param>
public DepthFirstOrder(Digraph g)
{
pre = new int[g.V];
post = new int[g.V];
postorder = new Queue <int>();
preorder = new Queue <int>();
marked = new bool[g.V];
for (int v = 0; v < g.V; v++)
{
if (!marked[v])
{
dfs(g, v);
}
}
}
public KosarajuSharirSCC(Digraph g)
{
//compute reverse postorder of reverse graph
DepthFirstOrder dfo = 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 dfo.ReversePost())
{
if (!marked[v])
{
dfs(g, v);
count++;
}
}
}
/// <summary>
/// run DFS in digraph G from vertex v and compute preorder/postorder
/// </summary>
/// <param name="g"></param>
/// <param name="v"></param>
private void dfs(Digraph g, int v)
{
if (marked[v])
{
return;
}
marked[v] = true;
pre[v] = preCounter++;
preorder.Enqueue(v);
foreach (int w in g.Adj(v))
{
if (!marked[v])
{
dfs(g, w);
}
}
postorder.Enqueue(v);
post[v] = postCounter++;
}
public DirectedDFS(Digraph g, int s)
{
marked = new bool[g.V];
dfs(g, s);
}
