// Merges 'toMerge' vertex into this vertex on 'mergeOn' vertex and removes both 'toMerge' and 'mergeOn' form graph
public Tuple <RemovedVertex, RemovedVertex> MergeWithAndRemove(Vertex toMerge, Vertex mergeOn)
{
var l1 = Neighbors.ToList();
var l2 = toMerge.Neighbors.ToList();
var i1 = l1.IndexOf(mergeOn);
var i2 = l2.IndexOf(mergeOn);
var l1top = l1.Take(i1);
var l1btm = l1.Skip(i1);
var l2top = l2.Take(i2);
var l2btm = l2.Skip(i2);
// Vertex becomes adjacent to all neighbors of 'toMerge' preserving planar order
Neighbors = l1btm.Union(l1top).Union(l2btm).Union(l2top).Distinct();
// Now we can safely remove 'mergeOn' from graph
var r1 = mergeOn.RemoveFromGraph();
// We must update adjacency list of all former neighbors of 'toMerge' vertex
foreach (var mergedNeighbor in toMerge.Neighbors)
{
var n = mergedNeighbor.Neighbors;
if (n.Contains(this))
{
n = n.Where(x => x.Id != toMerge.Id);
}
else
{
n = n.Select(x => x.Id == toMerge.Id ? this : x);
}
mergedNeighbor.Neighbors = n;
}
toMerge.IsRemoved = true;
var r2 = new RemovedVertex(toMerge.Id, toMerge.Neighbors.Select(x => x.Id).ToArray(), Id);
return(new Tuple <RemovedVertex, RemovedVertex>(r1, r2));
}
public bool IsAdjacentTo(Vertex v)
{
return(Neighbors.Any(n => n.Id == v.Id));
}
