static int MinCostUsingKruskal(WeightedGraph <int> g, int numEdges)
{
int minCost = 0;
//As it is a undirected graph, each edge will be added twice, hence size will be twice the number of edges.
Tuple <int, int, int>[] edgeList = new Tuple <int, int, int> [2 * numEdges];
// Get Iterartor to traverse adjList
Dictionary <int, List <Tuple <int, int> > > .Enumerator it = g.adjList.GetEnumerator();
int index = 0;
while (it.MoveNext())
{
//Get iterator to traverse neighbour list of current node
List <Tuple <int, int> > .Enumerator nbrIterator = it.Current.Value.GetEnumerator();
while (nbrIterator.MoveNext())
{
int curVtx = it.Current.Key;
int curNbr = nbrIterator.Current.Item1;
int curWt = nbrIterator.Current.Item2;
edgeList[index++] = new Tuple <int, int, int>(curVtx, curNbr, curWt);
}
}
Array.Sort(edgeList, delegate(Tuple <int, int, int> t1, Tuple <int, int, int> t2) {
if (t1.Item3 < t2.Item3)
{
return(-1);
}
else
{
return(1);
}
});
UnionSet edgeSet = new UnionSet(g.numVertices);
for (int i = 0; i < 2 * numEdges; ++i)
{
var curEdge = edgeList[i];
int vtx1 = curEdge.Item1;
int vtx2 = curEdge.Item2;
if (edgeSet.IsSameSet(vtx1, vtx2) == false)
{
// curEdge is significant
minCost += curEdge.Item3;
edgeSet.MakeUnion(vtx1, vtx2);
}
}
return(minCost);
}
