private static float CalcWeight(VertexParent V1, VertexParent V2)
{
byte red1, red2;
byte green1, green2;
byte blue1, blue2;
red1 = (byte)(V1.V >> 16);
red2 = (byte)(V2.V >> 16);
green1 = (byte)(V1.V >> 8);
green2 = (byte)(V2.V >> 8);
blue1 = (byte)(V1.V);
blue2 = (byte)(V2.V);
return((float)Math.Sqrt((red2 - red1) * (red2 - red1) + (green2 - green1) * (green2 - green1) + (blue2 - blue1) * (blue2 - blue1)));
}
public static List <Edge> PrimMST(List <int> D)
{
List <Edge> MSTList = new List <Edge>();
// final list contains the MST
FastPriorityQueue <VertexParent> FP = new FastPriorityQueue <VertexParent>(D.Count);
// Priority queue sorts the priority of edges' weights each time .
VertexParent [] VP = new VertexParent[D.Count];
// array holding each node and it's parent node.
VP[0] = new VertexParent(D[0], null); // initializing the first node in the MST.
FP.Enqueue(VP[0], 0); // inserting the first node into the priority queue.
float w;
for (int i = 1; i < D.Count; i++)
{
// intializing all the weights with OO value.
VP[i] = new VertexParent(D[i], null);
FP.Enqueue(VP[i], int.MaxValue);
}
while (FP.Count != 0)
{
VertexParent Top = FP.Dequeue(); // get the minimum priority
if (Top.P != null) // if it is not the starting node.
{
Edge E;
E.V1 = Top.V;
E.V2 = (int)(Top.P);
E.Weight = (float)(Top.Priority);
MSTList.Add(E); // add the minimum weight to the MST.
}
foreach (var unit in FP) // modify the priority each time .
{
w = CalcWeight(unit, Top); // calculates the weight between the current node and the top node.
if (w < unit.Priority)
{
unit.P = Top.V;
FP.UpdatePriority(unit, w);
}
}
}
return(MSTList);
}