public static void KruskalSpanningTree(DrawingSurface ds)
{
if (!ds.IsFullyConnected() || ds.IsDirected())
{
ErrorBox err = new ErrorBox("Graph has to be undirected and fully connected");
err.ShowDialog();
return;
}
var spanningTreeColor = Color.Green;
var edgesNum = ds.Edges.Count;
var adjMatrix = ds.GetDistMatrix();
var cost = .0;
var result = new List <Tuple <int, int> > {
};
var treeId = new List <int> {
};
ds.Edges.OrderBy(x => adjMatrix[x.start, x.end]);
for (var i = 0; i < ds.Vertices.Count; ++i)
{
treeId.Add(i);
}
for (var i = 0; i < edgesNum; ++i)
{
(var start, var end) = (ds.Edges[i].start, ds.Edges[i].end);
var weight = adjMatrix[start, end];
if (treeId[start] != treeId[end])
{
cost += weight;
for (var k = 0; k < ds.Edges.Count; ++k)
{
if (((ds.Edges[k].start == start && ds.Edges[k].end == end) ||
(ds.Edges[k].start == end && ds.Edges[k].end == start)))
{
ds.Edges[k].fillColor = spanningTreeColor;
ds.Vertices[ds.Edges[k].start].fillColor = spanningTreeColor;
ds.Vertices[ds.Edges[k].end].fillColor = spanningTreeColor;
ds.Invalidate();
Thread.Sleep(2000);
}
}
int oldId = treeId[end], newId = treeId[start];
for (var j = 0; j < ds.Vertices.Count; ++j)
{
if (treeId[j] == oldId)
{
treeId[j] = newId;
}
}
}
}
Thread.Sleep(5000);
ClearEdges(ds);
ClearVertices(ds);
}
public static void PrimSpanningTree(DrawingSurface ds)
{
if (!ds.IsFullyConnected() || ds.IsDirected())
{
ErrorBox err = new ErrorBox("Graph has to be undirected and fully connected");
err.ShowDialog();
return;
}
const int INF = int.MaxValue;
var vertexNum = ds.Vertices.Count;
var spanningTreeColor = Color.Red;
var adjMatrix = ds.GetDistMatrix();
var used = new bool[vertexNum];
double[] minEdge = Enumerable.Repeat((double)INF, vertexNum).ToArray();
int[] selectedEdge = Enumerable.Repeat(-1, vertexNum).ToArray();
minEdge[0] = 0;
for (var i = 0; i < vertexNum; ++i)
{
var vertex = -1;
for (var j = 0; j < vertexNum; ++j)
{
if (!used[j] && (vertex == -1 || minEdge[j] < minEdge[vertex]))
{
vertex = j;
}
}
if (minEdge[vertex] == INF)
{
ErrorBox err = new ErrorBox("Minimum spanning tree cannot be found");
err.ShowDialog();
return;
}
used[vertex] = true;
if (selectedEdge[vertex] != -1)
{
for (var k = 0; k < ds.Edges.Count; ++k)
{
if (((ds.Edges[k].start == vertex && ds.Edges[k].end == selectedEdge[vertex]) ||
(ds.Edges[k].start == selectedEdge[vertex] && ds.Edges[k].end == vertex)))
{
ds.Edges[k].fillColor = spanningTreeColor;
ds.Invalidate();
ds.Vertices[ds.Edges[k].start].fillColor = spanningTreeColor;
ds.Vertices[ds.Edges[k].end].fillColor = spanningTreeColor;
ds.Invalidate();
Thread.Sleep(2000);
}
}
}
for (var toVertex = 0; toVertex < vertexNum; ++toVertex)
{
if (adjMatrix[vertex, toVertex] < minEdge[toVertex])
{
minEdge[toVertex] = adjMatrix[vertex, toVertex];
selectedEdge[toVertex] = vertex;
}
}
}
Thread.Sleep(5000);
ClearEdges(ds);
ClearVertices(ds);
ds.Invalidate();
}