# Avl tree node insertion in scala

Scala program for Avl tree node insertion. Here problem description and other solutions.

``````// Scala program
// AVL Tree insertion
// Avl Tree Node
class TreeNode(var data: Int,
var height: Int,
var left: TreeNode,
var right: TreeNode)
{
def this(data: Int)
{
// Set node value of avl tree
this(data, 1, null, null);
}
}
class AvlTree(
// Tree root node
var root: TreeNode)
{
def this()
{
this(null);
}
// Get the height of given node
def getHeight(node: TreeNode): Int = {
if (node == null)
{
return 0;
}
return node.height;
}
// Get the max value of given two numbers
def maxHeight(a: Int, b: Int): Int = {
if (a > b)
{
return a;
}
else
{
return b;
}
}
// Perform the Right rotate operation
def rightRotate(node: TreeNode): TreeNode = {
// Get left child node
var leftNode: TreeNode = node.left;
// Get left node right subtree
var rightSubtree: TreeNode = leftNode.right;
// Update the left and right subtree
leftNode.right = node;
node.left = rightSubtree;
// Change the height of modified node
node.height = maxHeight(getHeight(node.left),
getHeight(node.right)) + 1;
leftNode.height = maxHeight(
getHeight(leftNode.left),
getHeight(leftNode.right)) + 1;
return leftNode;
}
// Perform the Left Rotate operation
def leftRotate(node: TreeNode): TreeNode = {
// Get right child node
var rightNode: TreeNode = node.right;
// Get right node left subtree
var leftSubtree: TreeNode = rightNode.left;
// Update the left and right subtree
rightNode.left = node;
node.right = leftSubtree;
// Change the height of modified node
node.height = maxHeight(
getHeight(node.left), getHeight(node.right)) + 1;
rightNode.height = maxHeight(
getHeight(rightNode.left),
getHeight(rightNode.right)) + 1;
return rightNode;
}
// Get the balance factor
def getBalanceFactor(node: TreeNode): Int = {
if (node == null)
{
return 0;
}
return getHeight(node.left) - getHeight(node.right);
}
// Recursively, add a node in AVL tree
// Duplicate keys (data) are not allowed
def addNode(node: TreeNode, data: Int): TreeNode = {
if (node == null)
{
// Return a new node
return new TreeNode(data);
}
if (data < node.data)
{
}
else if (data > node.data)
{
}
else
{
// When given key data already exists
return node;
}
// Change the height of current node
node.height = 1 + maxHeight(
getHeight(node.left), getHeight(node.right));
// Get balance factor of a node
var factor: Int = getBalanceFactor(node);
// LL Case
if (factor > 1 && data < node.left.data)
{
return rightRotate(node);
}
// RR Case
if (factor < -1 && data > node.right.data)
{
return leftRotate(node);
}
// LL Case
if (factor > 1 && data > node.left.data)
{
node.left = leftRotate(node.left);
return rightRotate(node);
}
// RR Case
if (factor < -1 && data < node.right.data)
{
node.right = rightRotate(node.right);
return leftRotate(node);
}
return node;
}
// Print the tree in preorder form
def preorder(node: TreeNode): Unit = {
if (node != null)
{
print("  " + node.data);
preorder(node.left);
preorder(node.right);
}
}
// Print the tree in inorder form
def inorder(node: TreeNode): Unit = {
if (node != null)
{
inorder(node.left);
print("  " + node.data);
inorder(node.right);
}
}
// Print the tree in postorder form
def postorder(node: TreeNode): Unit = {
if (node != null)
{
postorder(node.left);
postorder(node.right);
print("  " + node.data);
}
}
}
object Main
{
def main(args: Array[String]): Unit = {
var tree: AvlTree = new AvlTree();
/*
Resultant  AVL Tree
-----------------
7
/  \
/    \
4      17
/ \     / \
2   5  13  19
/ \     /
-3   3   11
*/
print("Resultant AVL Tree");
print("\nPreorder  :");
tree.preorder(tree.root);
print("\nInorder   :");
tree.inorder(tree.root);
print("\nPostorder :");
tree.postorder(tree.root);
}
}``````

Output

``````Resultant AVL Tree
Preorder  :  7  4  2  -3  3  5  17  13  11  19
Inorder   :  -3  2  3  4  5  7  11  13  17  19
Postorder :  -3  3  2  5  4  11  13  19  17  7``````

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