public void printChildren(int key)
{
BST_Node p = returnNode(key);
if (p != null)
{
Console.WriteLine("Parent node = {0}", p.Key);
if (p.Left == null)
{
Console.WriteLine("Left child = null");
}
else
{
Console.WriteLine("Left child = {0}", p.Left.Key);
}
if (p.Right == null)
{
Console.WriteLine("Right child = null");
}
else
{
Console.WriteLine("Right child = {0}", p.Right.Key);
}
}
else
{
Console.WriteLine("Key {0} is not in the tree", key);
}
}
private BST_Node returnNodePrivate(int key, BST_Node p)
{
if (p != null)
{
if (key == p.Key)
{
return(p);
}
else
{
if (key < p.Key)
{
return(returnNodePrivate(key, p.Left));
}
else
{
return(returnNodePrivate(key, p.Right));
}
}
}
else
{
return(p);
}
}
private void removeMatch(BST_Node parent, BST_Node match, bool left)
{
if (root != null)
{
int matchKey = match.Key;
int smallestInRightSubtree;
if (match.Left == null && match.Right == null)
{
if (left)
{
parent.Left = null;
}
else
{
parent.Right = null;
}
match = null;
Console.WriteLine("The node containing key {0} was removed", matchKey);
}
else if (match.Left == null && match.Right != null)
{
if (left)
{
parent.Left = match.Right;
}
else
{
parent.Right = match.Right;
}
match.Right = null;
match = null;
Console.WriteLine("The node containing key {0} was removed", matchKey);
}
else if (match.Left != null && match.Right == null)
{
if (left)
{
parent.Left = match.Left;
}
else
{
parent.Right = match.Left;
}
match.Left = null;
match = null;
Console.WriteLine("The node containing key {0} was removed", matchKey);
}
else
{
smallestInRightSubtree = findSmallestPrivate(match.Right);
removeNodePrivate(smallestInRightSubtree, match);
match.Key = smallestInRightSubtree;
}
}
else
{
Console.WriteLine("Cannot remove match, the tree is empty");
}
}
private BST_Node createLeaf(int key)
{
BST_Node n = new BST_Node();
n.Key = key;
n.Left = null;
n.Right = null;
return(n);
}
private void removeSubtree(BST_Node p)
{
if (p != null)
{
if (p.Left != null)
{
removeSubtree(p.Left);
}
if (p.Right != null)
{
removeSubtree(p.Right);
}
Console.WriteLine("Deleting the node containing key {0}", p.Key);
p = null;
}
}
private void printInOrderPrivate(BST_Node p)
{
if (root != null)
{
if (p.Left != null)
{
printInOrderPrivate(p.Left);
}
Console.Write("{0} ", p.Key);
if (p.Right != null)
{
printInOrderPrivate(p.Right);
}
}
else
{
Console.WriteLine("The tree is empty");
}
}
private void removeNodePrivate(int key, BST_Node p)
{
if (root != null)
{
if (root.Key == key)
{
removeRootMatch();
}
else
{
if (key < p.Key && p.Left != null)
{
if (p.Left.Key == key)
{
removeMatch(p, p.Left, true);
}
else
{
removeNodePrivate(key, p.Left);
}
}
else if (key > p.Key && p.Right != null)
{
if (p.Right.Key == key)
{
removeMatch(p, p.Right, true);
}
else
{
removeNodePrivate(key, p.Right);
}
}
else
{
Console.WriteLine("The key {0} was not found in the tree", key);
}
}
}
else
{
Console.WriteLine("The tree is empty");
}
}
private int findSmallestPrivate(BST_Node p)
{
if (root == null)
{
Console.WriteLine("The tree is empty");
return(-1);
}
else
{
if (p.Left != null)
{
return(findSmallestPrivate(p.Left));
}
else
{
return(p.Key);
}
}
}
private void removeRootMatch()
{
if (root != null)
{
BST_Node delNode = root;
int rootKey = root.Key;
int smallestInRightSubtree;
if (root.Left == null && root.Right == null)
{
root = null;
Console.WriteLine("The root node with key {0} was deleted. Now the tree is empty", rootKey);
}
else if (root.Left == null && root.Right != null)
{
root = root.Right;
delNode.Right = null;
delNode = null;
Console.WriteLine("The root node with key {0} was deleted. The new root contains key {1}", rootKey, root.Key);
}
else if (root.Left != null && root.Right == null)
{
root = root.Left;
delNode.Left = null;
delNode = null;
Console.WriteLine("The root node with key {0} was deleted. The new root contains key {1}", rootKey, root.Key);
}
else
{
smallestInRightSubtree = findSmallestPrivate(root.Right);
removeNodePrivate(smallestInRightSubtree, root);
root.Key = smallestInRightSubtree;
Console.WriteLine("The root node containing key {0} was overwritten with key {1}", rootKey, root.Key);
}
}
else
{
Console.WriteLine("Cannot remove key, the tree is empty");
}
}
private void addLeafPrivate(int key, BST_Node p)
{
if (root == null)
{
root = createLeaf(key);
}
else if (key < p.Key)
{
if (p.Left != null)
{
addLeafPrivate(key, p.Left);
}
else
{
p.Left = createLeaf(key);
}
}
else if (key > p.Key)
{
if (p.Right != null)
{
addLeafPrivate(key, p.Right);
}
else
{
p.Right = createLeaf(key);
}
}
else
{
Console.WriteLine("The key {0} has already been added to the tree!");
}
}
public BinarySearchTree()
{
root = null;
}
