private static long Count(RootedTreeNode node, int k)
{
long avail = k;
if (node.Children.Length == 0)
{
return(1);
}
if (node.Parent != null)
{
avail -= node.Parent.Node.Degree;
}
if (avail <= 0)
{
return(0);
}
long prod = 1;
for (int i = 0; i < node.Children.Length; i++)
{
prod *= avail;
prod %= MOD;
prod *= Count(node.Children[i], k);
prod %= MOD;
avail--;
}
return(prod);
}
private RootedTreeNode[,] PreprocessLCA()
{
int N = RootedTreeNodes.Length, M = 0;
while ((1 << M) < N)
{
M++;
}
var p = new RootedTreeNode[N, M];
for (int i = 0; i < N; i++)
{
p[i, 0] = RootedTreeNodes[i].Parent;
}
for (int j = 1; 1 << j < N; j++)
{
for (int i = 0; i < N; i++)
{
if (p[i, j - 1] != null)
{
p[i, j] = p[p[i, j - 1].Node.Index, j - 1];
}
}
}
return(p);
}
public RootedTree(Graph graph, Node root)
{
if (graph == null || root == null || root.Graph != graph || graph.Edges.Count != graph.Nodes.Count - 1)
{
throw new ArgumentException();
}
RootedTreeNodes = new RootedTreeNode[graph.Nodes.Count];
Root = new RootedTreeNode(this, root, null);
}
public RootedTreeNode GetLowestCommonAncestor(RootedTreeNode p, RootedTreeNode q)
{
if (lcaPreprocess == null)
{
lcaPreprocess = PreprocessLCA();
}
if (p.Level < q.Level)
{
RootedTreeNode tmp = p;
p = q;
q = tmp;
}
int log;
for (log = 1; 1 << log <= p.Level; log++)
{
;
}
log--;
for (int i = log; i >= 0; i--)
{
if (p.Level - (1 << i) >= q.Level)
{
p = lcaPreprocess[p.Node.Index, i];
}
}
if (p == q)
{
return(p);
}
for (int i = log; i >= 0; i--)
{
if (lcaPreprocess[p.Node.Index, i] != null &&
lcaPreprocess[p.Node.Index, i] != lcaPreprocess[q.Node.Index, i])
{
p = lcaPreprocess[p.Node.Index, i];
q = lcaPreprocess[q.Node.Index, i];
}
}
return(p.Parent);
}
public RootedTreeNode(RootedTree tree, Node node, RootedTreeNode parent)
{
Tree = tree;
Node = node;
Parent = parent;
Level = parent == null ? 0 : (parent.Level + 1);
var children = new List <RootedTreeNode>(node.Degree);
foreach (Node child in Node.GetAdjacentNodes().Where(x => Parent == null || x != Parent.Node))
{
children.Add(new RootedTreeNode(tree, child, this));
}
Children = children.ToArray();
tree.SetNode(this);
}
internal void SetNode(RootedTreeNode treeNode)
{
RootedTreeNodes[treeNode.Node.Index] = treeNode;
}
