void Dfs1(Node node)
{
node.Index = nextSCCIndex++;
node.LowLink = node.Index;
nodeStack.Push (node);
foreach (var to in node.PointsTo) {
if (to.Index == 0) {
Dfs1 (to);
node.LowLink = System.Math.Min (node.LowLink, to.LowLink);
} else if (nodeStack.Contains (to)) {
node.LowLink = System.Math.Min (node.LowLink, to.Index);
}
}
if (node.LowLink == node.Index) {
NodeGroup g = new NodeGroup ();
Node n;
do {
n = nodeStack.Pop ();
n.Group = g;
g.Add (n);
} while (n != node);
groups.Add (g);
}
}
