/*This function recieves value from user and add it into the tree then
* compare the depth of the tree with logbase3/2(n) if depth exceeded the
* log value then scapegoat node is found and rebuild the tree rooted at
* scapegoat node*/
public void add(double x)
{
Snode u = new Snode(x);
int d = AddDepth(u);
Console.WriteLine("Inserted {0}", x);
Console.WriteLine("n={0}\tq= {1}\td={2}", n, q, d);
double z = logBase32(q);
Console.WriteLine("LogBase 2/3(q) ={0}", z);
Console.WriteLine();
Console.WriteLine("____________");
if (d > logBase32(q))
{
Console.WriteLine("Depth exceeded");
Console.WriteLine("Finding ScapeGoat Node");
Console.WriteLine("Rebuliding tree rooted at ScapeGoat Node");
Snode w = u.parent;
while (3 * size(w) <= 2 * size(w.parent))
{
w = w.parent;
}
rebuild(w.parent);
}
}
/* Provides Predecessor*/
public Snode Predecessor(Snode node)
{
if (node == null)
{
return(null);
}
return(Maximum(node.left));
}
/* Provides Successor*/
public Snode Successor(Snode node)
{
if (node == null)
{
return(null);
}
return(Minimum(node.right));
}
private void inorder(Snode node)
{
if (node != null)
{
inorder(node.left);
Console.WriteLine(node.value + " ");
inorder(node.right);
}
}
/*Convert bst to array*/
private int packintoarray(Snode u, Snode[] a, int i)
{
if (u == null)
{
return(i);
}
i = packintoarray(u.left, a, i);
a[i++] = u;
return(packintoarray(u.right, a, i));
}
/* Function to add values.
* This function also provides the depth of the tree.*/
private int AddDepth(Snode u)
{
Snode w = root;
if (w == null)
{
root = u;
n++;
q++;
return(0);
}
bool done = false;
int d = 0;
do
{
if (u.value < w.value)
{
if (w.left == null)
{
w.left = u;
u.parent = w;
done = true;
}
else
{
w = w.left;
}
}
else if (u.value > w.value)
{
if (w.right == null)
{
w.right = u;
u.parent = w;
done = true;
}
else
{
w = w.right;
}
}
else
{
return(-1);
}
d++;
}while (!done);
n++;
q++;
return(d);
}
/*This function call the delete function and then check if
* tree is balanced or not. If tree is not balanced then it
* rebuild the whole tree from root*/
public void Delete(double e)
{
root = Delete(root, e);
if (root != null)
{
n--;
Console.WriteLine("Value of n after deletion :: " + n);
if (2 * n < q)
{
rebuild(root);
q = n;
}
}
}
/*Function to count the size of current node recursively*/
private int size(Snode u)
{
if (u == null)
{
return(0);
}
else
{
int l = 1;
l = l + size(u.left);
l = l + size(u.right);
return(l);
}
}
/*Find maximum node from the tree*/
public Snode Maximum(Snode node)
{
if (node == null)
{
return(null);
}
if (node.right == null)
{
return(node);
}
else
{
return(Maximum(node.right));
}
}
/* Find minimum node from the tree*/
public Snode Minimum(Snode node)
{
if (node == null)
{
return(null);
}
if (node.left == null)
{
return(node);
}
else
{
return(Minimum(node.left));
}
}
/*Uses BST rule to delete any node from the Scapegoat tree*/
private Snode Delete(Snode node, double e)
{
if (node == null)
{
return(null);
}
if (node.value == e)
{
if (node.left == null && node.right == null)
{
return(null);
}
if (node.left != null && node.right == null)
{
return(node.left);
}
if (node.right != null && node.left == null)
{
return(node.right);
}
if (node.right != null)
{
Snode succ = Successor(node);
node.value = succ.value;
node.right = Delete(node.right, succ.value);
}
else
{
Snode pred = Predecessor(node);
node.value = pred.value;
node.left = Delete(node.left, pred.value);
}
return(node);
}
if (e < node.value)
{
node.left = Delete(node.left, e);
}
else
{
node.right = Delete(node.right, e);
}
return(node);
}
private double Search(Snode node, double e)
{
if (node == null)
{
return(-1);
}
if (node.value == e)
{
return(node.value);
}
if (e < node.value)
{
return(Search(node.left, e));
}
else
{
return(Search(node.right, e));
}
}
/*Function to rebuild a tree rooted at Scapegoat node*/
private void rebuild(Snode u)
{
int ns = size(u);
Snode p = u.parent;
Snode[] a = new Snode[ns];
packintoarray(u, a, 0);
if (p == null)
{
root = BuildBalanced(a, 0, ns);
root.parent = null;
}
else if (p.right == u)
{
p.right = BuildBalanced(a, 0, ns);
p.right.parent = p;
}
else
{
p.left = BuildBalanced(a, 0, ns);
p.left.parent = p;
}
}
/*Constructor to intialize root 'q' and 'n'*/
public ScapeGoat()
{
root = null;
n = 0;
q = 0;
}