public void DijkstraSPTest()
{
EdgeWeightedDiagraph ewg;
using (StreamReader sr = new StreamReader(@"E:\Study\ALG2017\ALGRKC\dataSelf\tinyEWD.txt"))
{
ewg = new EdgeWeightedDiagraph(sr);
}
int s = 0;
DijkstraSP SP = new DijkstraSP(ewg, s);
for (int dest = 0; dest < ewg.V(); dest++)
{
if (SP.HasPathTo(dest))
{
Console.Write(s + " to " + dest);
Console.Write(" (" + SP.DistanceTo(dest) + "):");
foreach (DirectedEdge de in SP.PathTo(dest))
{
Console.Write(de + " ");
}
Console.WriteLine();
}
}
}
public TopologicalOrder(EdgeWeightedDiagraph ewg)
{
DirectedCycle directedCycle = new DirectedCycle(ewg);
if (!directedCycle.HasCycle()) // if it's a DAG, then we can continue to get the Topological Order
{
DepthFirstOrder dfsOrder = new DepthFirstOrder(ewg);
topologicalOder = dfsOrder.PostReverseOrder();
}
}
public DepthFirstOrder(EdgeWeightedDiagraph g)
{
isMarked = new bool[g.V()];
for (int i = 0; i < g.V(); i++)
{
if (!isMarked[i])
{
DFS(g, i);
}
}
}
//added overloaded constructor to handle EdgeWeightedDiagraph
public DirectedCycle(EdgeWeightedDiagraph dg)
{
marked = new bool[dg.V()];
onStack = new bool[dg.V()];
edgeTo = new int[dg.V()];
for (int i = 0; i < dg.V(); i++)
{
if (!marked[i])
{
DFS(dg, i);
}
}
}
void DFS(EdgeWeightedDiagraph g, int source)
{
isMarked[source] = false;
preOrder.Enqueue(source);
foreach (DirectedEdge de in g.AdjList(source))
{
int from = de.From(), to = de.To();
int v;
v = to;// source == from ? to : from;
if (!isMarked[v])
{
DFS(g, v);
}
}
postOrder.Enqueue(source);
postReverseOrder.Push(source);
}
//added overloaded DFS method to handle EdgeWeightedDiagraph, ideally we should design EdgeWeightedDiagraph to inherit from Diagraph
void DFS(EdgeWeightedDiagraph g, int s)
{
marked[s] = true;
onStack[s] = true;
foreach (DirectedEdge de in g.AdjList(s))
{
int from = de.From(), to = de.To();
int v;
v = to;// s == from ? to : from;
if (hasCycle)
{
return;
}
if (!marked[v])
{
edgeTo[v] = s;
DFS(g, v);
}
else
{
if (onStack[v]) // this means, we hit v agin in a cycle
{
hasCycle = true;
stackCycle = new Stack <int>();
for (int x = s; x != v; x = edgeTo[x])//starting from the parent of the current node, until it hits the current node
{
stackCycle.Push(x);
}
stackCycle.Push(v); // push the current node
stackCycle.Push(s); // push the parent node of the current again to for the loop
}
}
}
onStack[s] = false;
}
