public void BuildInducedGraph(List <int> verticesIndexes)
{
foreach (var index in verticesIndexes)
{
foreach (var incidentEdge in VerticesList[index - 1].AdjacencyList)
{
var adjacencyVertex = incidentEdge.IncidentTo.AdjacencyList;
adjacencyVertex.Remove(adjacencyVertex.First(edge => edge.IncidentTo.Index == index));
}
for (int i = 0; i < EdgesList.Count; i++)
{
if (EdgesList[i].First.Index == index || EdgesList[i].Second.Index == index)
{
EdgesList.RemoveAt(i);
}
}
}
foreach (var vertexToDeleteIndex in verticesIndexes)
{
VerticesList.RemoveAt(vertexToDeleteIndex - 1);
}
Size -= 1;
}
/// <summary>
/// Алгоритм Джонсона. Сложность 0(V^2*lgV + VE), если Фибоначчиевая куча, или 0(VE*lgV).
/// Вычисление кратчайших путей между всеми парами вершин
/// </summary>
public string JohnsonAlgorithm()
{
Size += 1;
VerticesList.Add(new Vertex(Size));
Vertex curVertexFrom = VerticesList[Size - 1];
for (int i = 0; i < Size - 1; i++)
{
Vertex curVertexTo = VerticesList[i];
IncidentEdge curEdge = new IncidentEdge(curVertexTo, 0);
curVertexFrom.AdjacencyList.Add(curEdge);
}
if (BellmanFordAlgorithm(curVertexFrom) == false)
{
Console.WriteLine("Входной граф содержит цикл с отрицательным весом");
}
else
{
foreach (var vertex in VerticesList)
{
foreach (var incidentEdge in vertex.AdjacencyList)
{
incidentEdge.Weight = incidentEdge.Weight + vertex.Distance - incidentEdge.IncidentTo.Distance;
}
}
VerticesList.RemoveAt(Size - 1);
Size -= 1;
int[] Distances = new int[Size];
for (int i = 0; i < Size; i++)
{
Distances[i] = VerticesList[i].Distance;
}
int[,] matrix = new int[Size, Size];
for (int i = 0; i < Size; i++)
{
Dijkstra(VerticesList[i]);
for (int j = 0; j < Size; j++)
{
matrix[i, j] = VerticesList[j].Distance + Distances[j] - Distances[i];
}
}
StringBuilder output = new StringBuilder();
for (int i = 0; i < Size; i++)
{
for (int j = 0; j < Size; j++)
{
output.Append(matrix[i, j] + " ");
}
output.Append("\n");
}
Console.WriteLine(output);
return(output.ToString());
}
return(null);
}