public KosarajuAlgorithm(DirectedGraph Graph)
{
_strongConnectedComponentEdges = new List<List<DirectedEdge>>();
_strongConnectedComponentVertices = new List<List<int>>();
BuildStrongConnectedComponents(Graph);
}
public TopologicalSorting(DirectedGraph Graph)
{
_topologicalSort = new List<int>();
bool[] mark = new bool[Graph.VerticesCount];
for (int i = 0; i < Graph.VerticesCount; ++i)
if (!mark[i])
DFS(i, mark, Graph);
}
public DirectedGraph(DirectedGraph g)
: this(g.VerticesCount)
{
for (int i = 0; i < g.VerticesCount; ++i)
for (int j = 0; j < g[i].Count; ++j)
{
Graph[i].Add(g[i, j]);
++EdgesCount;
}
}
void DFS(int vertex, bool[] mark, DirectedGraph Graph)
{
mark[vertex] = true;
for (int i = 0; i < Graph.GetVertexDegree(vertex); ++i)
if (!mark[Graph.GetEdge(vertex, i).End])
DFS(Graph.GetEdge(vertex, i).End, mark, Graph);
_topologicalSort.Add(vertex);
}
void AddStrongConnectedComponent(int vertex, int[] mark, DirectedGraph Graph)
{
mark[vertex] = StrongConnectedComponentCount;
_strongConnectedComponentVertices[StrongConnectedComponentCount].Add(vertex);
for (int i = 0; i < Graph.GetVertexDegree(vertex); ++i)
if (mark[Graph.GetEdge(vertex, i).End] == StrongConnectedComponentCount || mark[Graph.GetEdge(vertex, i).End] == -1)
{
_strongConnectedComponentEdges[StrongConnectedComponentCount].Add(Graph.GetEdge(vertex, i).Reverse());
if (mark[Graph.GetEdge(vertex, i).End] == -1)
AddStrongConnectedComponent(Graph.GetEdge(vertex, i).End, mark, Graph);
}
}
public static DirectedGraph ReadFromTxtFile(string fileName)
{
StreamReader inputFile = new StreamReader(fileName);
string fileContent = inputFile.ReadToEnd();
string[] inputData = fileContent.Split(new string[] { " ", "\r\n" }, StringSplitOptions.RemoveEmptyEntries);
var result = new DirectedGraph(int.Parse(inputData[0]));
int edgesCount = int.Parse(inputData[1]);
for (int i = 0; i < edgesCount; ++i)
{
DirectedEdge edge = new DirectedEdge(int.Parse(inputData[i * 2 + 2]) - 1, int.Parse(inputData[i * 2 + 3]) - 1);
result[edge.Begin].Add(edge);
}
return result;
}
public static DirectedGraph ReadFromConsole()
{
AllocConsole();
Console.Write("Enter a number of vertices, please: ");
int verticesCount = int.Parse(Console.ReadLine());
DirectedGraph result = new DirectedGraph(verticesCount);
Console.Write("Enter a number of edges, please: ");
int edgesCount = int.Parse(Console.ReadLine());
for (int i = 0; i < edgesCount; ++i)
{
Console.Write("Enter begin and end of {0} edge, please: ", i + 1);
string[] inputData = Console.ReadLine().Split(new string[]{" "}, StringSplitOptions.RemoveEmptyEntries);
DirectedEdge edge = new DirectedEdge(int.Parse(inputData[0]) - 1, int.Parse(inputData[1]) - 1);
result[edge.Begin].Add(edge);
}
FreeConsole();
return result;
}
private void BuildStrongConnectedComponents(DirectedGraph Graph)
{
TopologicalSorting topologicalSortedVertices = new TopologicalSorting(Graph);
DirectedGraph transposedGraph = Graph.Transposition();
int[] mark = new int[Graph.VerticesCount];
for (int i = 0; i < Graph.VerticesCount; ++i)
mark[i] = -1;
for (int i = transposedGraph.VerticesCount - 1; i >= 0; --i)
if (mark[topologicalSortedVertices[i]] == -1)
{
List<DirectedEdge> edges = new List<DirectedEdge>();
_strongConnectedComponentEdges.Add(edges);
List<int> vertices = new List<int>();
_strongConnectedComponentVertices.Add(vertices);
AddStrongConnectedComponent(topologicalSortedVertices[i], mark, transposedGraph);
_strongConnectedComponentVertices[StrongConnectedComponentCount].Sort();
++StrongConnectedComponentCount;
}
}
public DirectedGraph Transposition()
{
DirectedGraph result = new DirectedGraph(VerticesCount);
for (int i = 0; i < VerticesCount; ++i)
for (int j = 0; j < GetVertexDegree(i); ++j)
result.AddEdge(GetEdge(i, j).Reverse());
return result;
}
private void ReadGraphFromATextFile_Click(object sender, EventArgs e)
{
openInputTxt.ShowDialog();
string fileName = openInputTxt.FileName;
Graph = DirectedGraphReader.ReadFromTxtFile(fileName);
}
private void ReadGraphFromAConsole_Click(object sender, EventArgs e)
{
Graph = DirectedGraphReader.ReadFromConsole();
}