package DataStructures.Trees;

public class AVLTree {

 private Node root;

 private class Node {
 private int key;
 private int balance;
 private int height;
 private Node left, right, parent;

 Node(int k, Node p) {
 key = k;
 parent = p;
 }
 }

 public boolean insert(int key) {
 if (root == null)
 root = new Node(key, null);
 else {
 Node n = root;
 Node parent;
 while (true) {
 if (n.key == key)
 return false;

 parent = n;

 boolean goLeft = n.key > key;
 n = goLeft ? n.left : n.right;

 if (n == null) {
 if (goLeft) {
 parent.left = new Node(key, parent);
 } else {
 parent.right = new Node(key, parent);
 }
 rebalance(parent);
 break;
 }
 }
 }
 return true;
 }

 private void delete(Node node) {
 if (node.left == null && node.right == null) {
 if (node.parent == null) root = null;
 else {
 Node parent = node.parent;
 if (parent.left == node) {
 parent.left = null;
 } else parent.right = null;
 rebalance(parent);
 }
 return;
 }
 if (node.left != null) {
 Node child = node.left;
 while (child.right != null) child = child.right;
 node.key = child.key;
 delete(child);
 } else {
 Node child = node.right;
 while (child.left != null) child = child.left;
 node.key = child.key;
 delete(child);
 }
 }

 public void delete(int delKey) {
 if (root == null)
 return;
 Node node = root;
 Node child = root;

 while (child != null) {
 node = child;
 child = delKey >= node.key ? node.right : node.left;
 if (delKey == node.key) {
 delete(node);
 return;
 }
 }
 }

 private void rebalance(Node n) {
 setBalance(n);

 if (n.balance == -2) {
 if (height(n.left.left) >= height(n.left.right))
 n = rotateRight(n);
 else
 n = rotateLeftThenRight(n);

 } else if (n.balance == 2) {
 if (height(n.right.right) >= height(n.right.left))
 n = rotateLeft(n);
 else
 n = rotateRightThenLeft(n);
 }

 if (n.parent != null) {
 rebalance(n.parent);
 } else {
 root = n;
 }
 }

 private Node rotateLeft(Node a) {

 Node b = a.right;
 b.parent = a.parent;

 a.right = b.left;

 if (a.right != null)
 a.right.parent = a;

 b.left = a;
 a.parent = b;

 if (b.parent != null) {
 if (b.parent.right == a) {
 b.parent.right = b;
 } else {
 b.parent.left = b;
 }
 }

 setBalance(a, b);

 return b;
 }

 private Node rotateRight(Node a) {

 Node b = a.left;
 b.parent = a.parent;

 a.left = b.right;

 if (a.left != null)
 a.left.parent = a;

 b.right = a;
 a.parent = b;

 if (b.parent != null) {
 if (b.parent.right == a) {
 b.parent.right = b;
 } else {
 b.parent.left = b;
 }
 }

 setBalance(a, b);

 return b;
 }

 private Node rotateLeftThenRight(Node n) {
 n.left = rotateLeft(n.left);
 return rotateRight(n);
 }

 private Node rotateRightThenLeft(Node n) {
 n.right = rotateRight(n.right);
 return rotateLeft(n);
 }

 private int height(Node n) {
 if (n == null)
 return -1;
 return n.height;
 }

 private void setBalance(Node... nodes) {
 for (Node n : nodes) {
 reheight(n);
 n.balance = height(n.right) - height(n.left);
 }
 }

 public void printBalance() {
 printBalance(root);
 }

 private void printBalance(Node n) {
 if (n != null) {
 printBalance(n.left);
 System.out.printf("%s ", n.balance);
 printBalance(n.right);
 }
 }

 private void reheight(Node node) {
 if (node != null) {
 node.height = 1 + Math.max(height(node.left), height(node.right));
 }
 }

 public static void main(String[] args) {
 AVLTree tree = new AVLTree();

 System.out.println("Inserting values 1 to 10");
 for (int i = 1; i < 10; i++)
 tree.insert(i);

 System.out.print("Printing balance: ");
 tree.printBalance();
 }
}