private static AdjacencyListGraph <TWeight> ToAdjacencyGraph(int verticeCount, IEnumerable <Edge <TWeight> > edges, Action <AdjacencyListGraph <TWeight>, Edge <TWeight> > addEdge)
{
var graph = new AdjacencyListGraph <TWeight>(verticeCount);
foreach (var edge in edges)
{
addEdge(graph, edge);
}
return(graph);
}
private static PrimsResult PrimsAlgorithm(AdjacencyListGraph <decimal> graph)
{
var size = graph.Size();
//Initialize result with 0 as first vertex
var result = new PrimsResult(size);
result.Cost.SetValue(0, 0);
//priority queue of costs
var q = new MinPriorityQueue <decimal>(size, decimal.MaxValue);
for (var i = 0; i < size; i++)
{
q.Enqueue(i, result.Cost.GetValue(i));
}
//Walk
while (!q.IsEmpty())
{
//Console.WriteLine("Queue: {0}", q);
var currentIndex = q.Dequeue();
//Console.WriteLine("Extract: {0}", currentIndex);
foreach (var edge in graph.Neighbors(currentIndex))
{
var z = edge.Right;
var w = edge.Weight;
if (!q.Contains(z) || result.Cost.GetValue(z) <= w)
{
continue;
}
result.Cost.SetValue(z, w);
result.Parent.SetValue(z, currentIndex);
q.ChangePriority(z, w);
}
}
return(result);
}
