public Vertex[] GetEulerTour()
{
// For all n - 1 edges, we take the edge down to its child and then, eventually, back up
// to its parent. So each edge contributes 2 vertices to the tour, and we get the root
// initially without using any edges, so that's 2*(n - 1) + 1 = 2n - 1 vertices.
var eulerTour = new Vertex[2 * VertexCount - 1];
int eulerTourIndex = -1;
var verticesToVisit = new Stack <Vertex>();
verticesToVisit.Push(Root);
while (verticesToVisit.Count > 0)
{
var vertex = verticesToVisit.Peek();
eulerTour[++eulerTourIndex] = vertex;
// If the EulerTourInitialIndex is null, it's the first time we're visiting the vertex.
if (!vertex.EulerTourInitialIndex.HasValue)
{
vertex.Depth = 1 + (vertex.Parent?.Depth ?? -1);
vertex.EulerTourInitialIndex = eulerTourIndex;
}
if (vertex.EulerTourChildCounter == vertex.Children.Count)
{
verticesToVisit.Pop();
}
else
{
verticesToVisit.Push(vertex.Children[vertex.EulerTourChildCounter++]);
}
}
return(eulerTour);
}
private RootedTree(int vertexCount, int rootID)
{
var vertices = new Vertex[vertexCount];
for (int id = 0; id < vertexCount; ++id)
{
vertices[id] = new Vertex(this, id);
}
Vertices = vertices;
Root = vertices[rootID];
}
public MinimumDepthQueryObject(int index, Vertex value)
{
SegmentStartIndex = SegmentEndIndex = index;
MinimumDepthVertex = value;
}