private static Vertex[] CreateDirectedAcyclicGraph(int n)
{
Vertex[] vertices = new Vertex[n];
for (int i = 0; i < vertices.Length; i++)
{
vertices[i] = new Vertex();
}
for (int i = 0; i < vertices.Length; i++)
{
for (int j = 0; j < i; j++)
{
vertices[i].AddUnDirectedEdge(vertices[j]);
}
}
while (!TopologicalSortTestClass.IsDirectedAcyclicGraph(vertices))
{
TopologicalSortTestClass.RemoveRandomEdge(vertices);
}
foreach (Vertex v in vertices)
{
v.Reset();
}
return(vertices);
}
private static bool IsDirectedAcyclicGraph(Vertex[] vertices)
{
foreach (Vertex v in vertices)
{
v.Reset();
}
return(!vertices.Any(v => TopologicalSortTestClass.HasCycle(v)));
}
public void TopologicalSortTest()
{
for (int n = 0; n < 5; n++)
{
Vertex[] vertices = TopologicalSortTestClass.CreateDirectedAcyclicGraph(n);
Vertex[] order = TopologicalSort.Run(vertices);
for (int i = n - 1; i >= 0; i--)
{
foreach (Vertex v in vertices)
{
v.Reset();
}
DepthFirstSearch.Run(order[i]);
for (int j = 0; j < i; j++)
{
Assert.AreEqual(Color.White, order[j].Color);
}
}
}
}
private static bool HasCycle(Vertex vertex)
{
if (vertex.Color == Color.Gray)
{
return(true);
}
if (vertex.Color == Color.Black)
{
return(false);
}
vertex.Color = Color.Gray;
if (vertex.Vertices.Any(v => TopologicalSortTestClass.HasCycle(v)))
{
return(true);
}
vertex.Color = Color.Black;
return(false);
}
