/// <summary>
/// Kruskal algorithm
/// </summary>
/// <returns>return the min span tree for this grpah</returns>
public MatrixGraph Kruskal()
{
double[][] result = GetNonEdgeGraph();
List <EdgeNode> edgeNodes = new List <EdgeNode>(count);
for (int i = 0; i < count; i++)
{
for (int j = 0; j < count; j++)
{
double length = matrix[i][j];
if (length != maxDistance)
{
EdgeNode edgeNode = new EdgeNode(i, j, length);
edgeNodes.Add(edgeNode);
}
}
}
edgeNodes.Sort();
int addEdgeNumber = 0;
DisjointSet set = new DisjointSet(count);
for (int i = 0; i < edgeNodes.Count; i++)
{
int sourceIndex = edgeNodes[i].SourceIndex;
int destinationIndex = edgeNodes[i].DestinationIndex;
if (!set.IsInSameSet(sourceIndex, destinationIndex))
{
result[sourceIndex][destinationIndex] = edgeNodes[i].Length;
set.Union(sourceIndex, destinationIndex);
addEdgeNumber++;
}
if (addEdgeNumber == count)
{
break;
}
}
if (addEdgeNumber != count)
{
throw new InvalidOperationException("The graph isn't connected!");
}
return(new MatrixGraph(result, maxDistance));
}
public int CompareTo(EdgeNode other)
{
return(length.CompareTo(other.length));
}