private void Dfs(DiGraph g, int v)
{
_marked[v] = true;
_onStack[v] = true;
foreach (var w in g.Adj(v))
{
if (this.HasCycle())
{
return;
}
else if (!_marked[w])
{
Dfs(g, w);
}
else if (_onStack[w])
{
_cycle = new Stack <int>();
for (int i = v; i == w; i = _edgeTo[i])
{
_cycle.Push(i);
}
_cycle.Push(w);
_cycle.Push(v);
}
_onStack[w] = false;
}
}
public TopologicalSort(DiGraph g)
{
DirectedCycle Dc = new DirectedCycle(g);
if (!Dc.HasCycle())
{
DepthFirstOrder dfo = new DepthFirstOrder(g);
_order = dfo.ReversePostOrder;
}
}
//internal recursive processing method
private void dfs(DiGraph G, int v)
{
_marked[v] = true;
foreach (var w in G.Adj(v))
{
if (!_marked[w])
{
dfs(G, w);
}
}
}
public DirectedDFS(DiGraph G, IEnumerable <int> sources)
{
_marked = new bool[G.V];
foreach (var s in sources)
{
if (!_marked[s])
{
dfs(G, s);
}
}
}
public DirectedCycle(DiGraph g)
{
_marked = new bool[g.V];
_edgeTo = new int[g.V];
_onStack = new Boolean[g.V];
for (int i = 0; i < g.V; i++)
{
if (!_marked[i])
{
Dfs(g, i);
}
}
}
//creates and returns a new Digraph in reverse, listing all V's pointing TO the indexed v(preceding v's)
public DiGraph Reverse()
{
DiGraph R = new DiGraph(_v);
for (int i = 0; i < _v; i++)
{
foreach (var w in _adj[i])
{
R.AddEdge(w, i);
R._e++;
}
}
return(R);
}
private void Dfs(DiGraph g, int v)
{
PreOrder.Enqueue(v);
_marked[v] = true;
foreach (var w in g.Adj(v))
{
if (!_marked[w])
{
Dfs(g, w);
}
}
PostOrder.Enqueue(v);
ReversePostOrder.Push(v);
}
public DepthFirstOrder(DiGraph g)
{
_marked = new bool[g.V];
_preOrder = new Queue <int>();
_postOrder = new Queue <int>();
_reversePostOrder = new Stack <int>();
for (int v = 0; v < g.V; v++)
{
if (!_marked[v])
{
Dfs(g, v);
}
}
}
//inits the DS and calls the main processing method to start
public DirectedDFS(DiGraph G, int s)
{
_marked = new bool[G.V];
dfs(G, s);
}