public DirectedDFS(DiGraph G, IEnumerable<int> sources)
{
marked = new bool[G.V];
foreach (int s in sources)
if (!marked[s])
dfs(G, s);
}
private void dfs(DiGraph G, int v)
{
marked[v] = true;
foreach (int w in G.Adj(v))
if (!marked[w])
dfs(G, w);
}
static void Main(string[] args)
{
DiGraph dg = new DiGraph(5);
dg.addEdge(0, 1);
dg.addEdge(1, 2);
dg.addEdge(1, 3);
dg.addEdge(2, 4);
//dg.addEdge(4, 0); //Comment it for topological
dg.addEdge(4, 3);
Console.WriteLine(dg);
dg.ShowMarked();
dg.ShowCycle();
dg.ShowTopological();
Console.WriteLine("{0}-{1} is strongly connected : {2}", 0, 1, dg.isStonglyConnected(0, 1));
Console.WriteLine("{0}-{1} is reachable : {2}", 0, 3, dg.Reachable(0, 3));
Console.ReadKey();
}
public DirectedDFS(DiGraph G, int s)
{
if (s < 0 || s > G.V-1)
s = G.V-1;
marked = new bool[G.V];
dfs(G, s);
}
static void Main(string[] args)
{
DiGraph dg=new DiGraph(5);
dg.addEdge(0, 1);
dg.addEdge(1, 2);
dg.addEdge(1, 3);
dg.addEdge(2, 4);
//dg.addEdge(4, 0); //Comment it for topological
dg.addEdge(4, 3);
Console.WriteLine(dg);
dg.ShowMarked();
dg.ShowCycle();
dg.ShowTopological();
Console.WriteLine("{0}-{1} is strongly connected : {2}", 0, 1, dg.isStonglyConnected(0, 1));
Console.WriteLine("{0}-{1} is reachable : {2}", 0, 3, dg.Reachable(0, 3));
Console.ReadKey();
}
public DiGraph reverse()
{
DiGraph R = new DiGraph(V);
for (int v = 0; v < V; v++)
foreach (int w in Adj(v))
R.addEdge(w, v);
return R;
}
private IEnumerable<int> order; // topological order
#endregion Fields
#region Constructors
public Topological(DiGraph G)
{
DirectedCycle cyclefinder = new DirectedCycle(G);
if (!cyclefinder.hasCycle())
{
DepthFirstOrder dfs = new DepthFirstOrder(G);
order = dfs.ReversePost();
}
}
private bool[] onStack; // vertices on recursive call stack
#endregion Fields
#region Constructors
public DirectedCycle(DiGraph G)
{
onStack = new bool[G.V];
edgeTo = new int[G.V];
marked = new bool[G.V];
for (int v = 0; v < G.V; v++)
if (!marked[v])
dfs(G, v);
}
private void dfs(DiGraph G, int v)
{
pre.Enqueue(v);
marked[v] = true;
foreach (int w in G.Adj(v))
if (!marked[w])
dfs(G, w);
post.Enqueue(v);
reversePost.Push(v);
}
private Stack<int> reversePost; // vertices in reverse postorder
#endregion Fields
#region Constructors
public DepthFirstOrder(DiGraph G)
{
pre = new Queue<int>();
post = new Queue<int>();
reversePost = new Stack<int>();
marked = new bool[G.V];
for (int v = 0; v < G.V; v++)
if (!marked[v])
dfs(G, v);
}
private IEnumerable <int> order; // topological order
public Topological(DiGraph G)
{
DirectedCycle cyclefinder = new DirectedCycle(G);
if (!cyclefinder.hasCycle())
{
DepthFirstOrder dfs = new DepthFirstOrder(G);
order = dfs.ReversePost();
}
}
public static void ShowCycle(this DiGraph dg)
{
DirectedCycle Cycle = new DirectedCycle(dg);
if (Cycle.hasCycle())
{
Console.Write("Directed Graph Cycled in : ");
foreach (var e in Cycle.Cycle())
{
Console.Write("{0} ", e);
}
Console.WriteLine();
}
}
public static void ShowMarked(this DiGraph dg)
{
Console.Write("Marked: ");
DirectedDFS reachable = new DirectedDFS(dg, dg.V);
for (int v = 0; v < dg.V; v++)
{
if (reachable.Marked(v))
{
Console.Write(v + " ");
}
}
Console.WriteLine();
}
public static void ShowTopological(this DiGraph dg)
{
Topological top = new Topological(dg);
if (top.isDAG())
{
return;
}
Console.Write("Topological: ");
foreach (int v in top.Order)
{
Console.Write("{0} ", v);
}
Console.WriteLine();
}
private void dfs(DiGraph G, int v)
{
onStack[v] = true;
marked[v] = true;
foreach (int w in G.Adj(v))
if (this.hasCycle())
return;
else if (!marked[w])
{
edgeTo[w] = v;
dfs(G, w);
}
else if (onStack[w])
{
cycle = new Stack<int>();
for (int x = v; x != w; x = edgeTo[x])
cycle.Push(x);
cycle.Push(w);
cycle.Push(v);
}
onStack[v] = false;
}
