public RootedTreeNode(RootedTree tree, Node node, int parentIndex, int level)
{
Tree = tree;
Node = node;
Level = level;
_parentIndex = parentIndex;
var children = new List <RootedTreeNode>(node.Degree);
foreach (Node child in Node.GetAdjacentNodes().Where(x => x.Index != parentIndex))
{
children.Add(tree.GetNode(child.Index));
}
Children = children.ToArray();
tree.SetNode(this);
}
public void TestTreeLCA()
{
Random r = new Random(0);
for (int i = 0; i < 10; i++)
{
int N = r.Next(30000, 40000);
int[] perm = new int[N];
for (int j = 0; j < N; j++)
{
perm[j] = j;
}
for (int j = 0; j < N; j++)
{
int swap = j + r.Next(N - j);
int tmp = perm[j];
perm[j] = perm[swap];
perm[swap] = tmp;
}
Graph g = new Graph(N);
for (int j = 1; j < N; j++)
{
int a = r.Next(j);
g.AddEdge(perm[a], perm[j]);
}
RootedTree tree = new RootedTree(g, g.GetNode(perm[0]));
for (int j = 0; j < 100; j++)
{
int a = r.Next(N), b = r.Next(N);
RootedTreeNode p = tree.GetNode(a), q = tree.GetNode(b);
// Naive solution
var pp = p;
var qq = q;
List <RootedTreeNode> ptrail = new List <RootedTreeNode>(), qtrail = new List <RootedTreeNode>();
while (pp != null)
{
ptrail.Add(pp);
pp = pp.Parent;
}
while (qq != null)
{
qtrail.Add(qq);
qq = qq.Parent;
}
ptrail.Reverse();
qtrail.Reverse();
int k = 0;
while (k + 1 < ptrail.Count && k + 1 < qtrail.Count && ptrail[k + 1] == qtrail[k + 1])
{
k++;
}
RootedTreeNode expected = ptrail[k];
RootedTreeNode lca = tree.GetLowestCommonAncestor(p, q);
Assert.AreSame(expected, lca);
}
}
}