public List <Edge> GetKruskalsMST(Graph graph)
{
graph.Edges.Sort(new EdgeComparator());
DisjointSet disjointSet = new DisjointSet();
// Create as many disjoint sets as the total vertices
foreach (KeyValuePair <long, Vertex> vertexPair in graph.Verticies)
{
disjointSet.MakeSet(vertexPair.Value.Id);
}
List <Edge> resultEdges = new List <Edge>();
foreach (Edge edge in graph.Edges)
{
// Get the sets of two vertices of the edge
long root1 = disjointSet.FindSet(edge.Vertex1.Id);
long root2 = disjointSet.FindSet(edge.Vertex2.Id);
// Check if the vertices are in same set or different set
// If verties are in same set then ignore the edge
if (root1 == root2)
{
continue;
}
else
{
// If vertices are in different set then add the edge to result and union these two sets into one
resultEdges.Add(edge);
disjointSet.Union(edge.Vertex1.Id, edge.Vertex2.Id);
}
}
return(resultEdges);
}
public static void DisjointSetTest()
{
DisjointSet ds = new DisjointSet();
ds.MakeSet(1);
ds.MakeSet(2);
ds.MakeSet(3);
ds.MakeSet(4);
ds.MakeSet(5);
ds.MakeSet(6);
ds.MakeSet(7);
ds.Union(1, 2);
ds.Union(2, 3);
ds.Union(4, 5);
ds.Union(6, 7);
ds.Union(5, 6);
ds.Union(3, 7);
Console.WriteLine("DisjoinSet Demo :");
Console.WriteLine(ds.FindSet(1));
Console.WriteLine(ds.FindSet(2));
Console.WriteLine(ds.FindSet(3));
Console.WriteLine(ds.FindSet(4));
Console.WriteLine(ds.FindSet(5));
Console.WriteLine(ds.FindSet(6));
Console.WriteLine(ds.FindSet(7));
}
//=======================================================================================================================
public bool HasCycleUsingDisjointSets(Graph graph)
{
DisjointSet disjointSet = new DisjointSet();
foreach (KeyValuePair <long, Vertex> vertexPair in graph.Verticies)
{
disjointSet.MakeSet(vertexPair.Key);
}
foreach (Edge edge in graph.Edges)
{
long parent1 = disjointSet.FindSet(edge.Vertex1.Id);
long parent2 = disjointSet.FindSet(edge.Vertex2.Id);
if (parent1 == parent2)
{
return(true);
}
disjointSet.Union(edge.Vertex1.Id, edge.Vertex2.Id);
}
return(false);
}
