private static IEnumerable<Tree> MakeSet(Vertex[] nodes)
{
foreach (var n in nodes)
{
yield return new Tree(new[] { n }, null);
}
}
private static void Main()
{
Vertex[] nodes = new Vertex[]
{
new Vertex("a"),
new Vertex("b"),
new Vertex("c"),
new Vertex("d"),
new Vertex("e"),
new Vertex("f"),
new Vertex("g"),
new Vertex("h"),
new Vertex("i"),
new Vertex("j"),
new Vertex("k"),
new Vertex("l"),
};
Edge[] edges = new[]
{
new Edge(3, nodes[0], nodes[1]),
new Edge(5, nodes[0], nodes[2]),
new Edge(4, nodes[0], nodes[3]),
new Edge(3, nodes[1], nodes[4]),
new Edge(6, nodes[1], nodes[5]),
new Edge(2, nodes[2], nodes[3]),
new Edge(1, nodes[3], nodes[4]),
new Edge(2, nodes[4], nodes[5]),
new Edge(4, nodes[2], nodes[6]),
new Edge(5, nodes[3], nodes[7]),
new Edge(4, nodes[4], nodes[8]),
new Edge(5, nodes[5], nodes[9]),
new Edge(3, nodes[6], nodes[7]),
new Edge(6, nodes[7], nodes[8]),
new Edge(3, nodes[8], nodes[9]),
new Edge(6, nodes[6], nodes[10]),
new Edge(7, nodes[7], nodes[10]),
new Edge(5, nodes[8], nodes[11]),
new Edge(9, nodes[9], nodes[11]),
new Edge(8, nodes[10], nodes[11]),
};
Console.WriteLine(string.Join(", ", Kruskal(nodes, edges)));
}
private static IEnumerable<Edge> Kruskal(Vertex[] nodes, Edge[] edges)
{
var workingEdges = new Queue<Edge>(edges.OrderBy(e => e.Cost).ToArray());
var forest = MakeSet(nodes).ToArray();
Console.WriteLine("Forest: {0}", string.Join<Tree>("|", forest));
while (1 < forest.Count())
{
var edge = workingEdges.Dequeue();
var vtrees = TreesWith(edge.Ends[0], forest).ToArray();
var utrees = TreesWith(edge.Ends[1], forest).ToArray();
if (0 < vtrees.Length && 0 < utrees.Length)
{
forest = MakeUnions(vtrees, utrees, edge, forest).ToArray();
Console.WriteLine("Forest: {0}", string.Join<Tree>("|", forest));
}
}
return forest.First().Edges;
}
internal bool Contains(Vertex v)
{
return Nodes.Contains(v);
}
private static IEnumerable<Tree> TreesWith(Vertex v, IEnumerable<Tree> forest)
{
return from f in forest
where f.Contains(v)
select f;
}