Complete implementation of AVL tree in java
package tech.codingpoint.avltree;
public class AVLTree {
public class Node {
int key;
int height;
Node left;
Node right;
Node(int key) {
this.key = key;
}
}
private Node root;
public Node find(int key) {
Node current = root;
while (current != null) {
if (current.key == key) {
break;
}
current = current.key < key ? current.right : current.left;
}
return current;
}
public void insert(int key) {
root = insert(root, key);
}
public void delete(int key) {
root = delete(root, key);
}
public Node getRoot() {
return root;
}
public int height() {
return root == null ? -1 : root.height;
}
private Node insert(Node node, int key) {
if (node == null) {
return new Node(key);
} else if (node.key > key) {
node.left = insert(node.left, key);
} else if (node.key < key) {
node.right = insert(node.right, key);
} else {
throw new RuntimeException("duplicate Key!");
}
return rebalance(node);
}
private Node delete(Node node, int key) {
if (node == null) {
return node;
} else if (node.key > key) {
node.left = delete(node.left, key);
} else if (node.key < key) {
node.right = delete(node.right, key);
} else {
if (node.left == null || node.right == null) {
node = (node.left == null) ? node.right : node.left;
} else {
Node mostLeftChild = mostLeftChild(node.right);
node.key = mostLeftChild.key;
node.right = delete(node.right, node.key);
}
}
if (node != null) {
node = rebalance(node);
}
return node;
}
private Node mostLeftChild(Node node) {
Node current = node;
/* loop down to find the leftmost leaf */
while (current.left != null) {
current = current.left;
}
return current;
}
private Node rebalance(Node z) {
updateHeight(z);
int balance = getBalance(z);
if (balance > 1) {
if (height(z.right.right) > height(z.right.left)) {
z = rotateLeft(z);
} else {
z.right = rotateRight(z.right);
z = rotateLeft(z);
}
} else if (balance < -1) {
if (height(z.left.left) > height(z.left.right)) {
z = rotateRight(z);
} else {
z.left = rotateLeft(z.left);
z = rotateRight(z);
}
}
return z;
}
private Node rotateRight(Node y) {
Node x = y.left;
Node z = x.right;
x.right = y;
y.left = z;
updateHeight(y);
updateHeight(x);
return x;
}
private Node rotateLeft(Node y) {
Node x = y.right;
Node z = x.left;
x.left = y;
y.right = z;
updateHeight(y);
updateHeight(x);
return x;
}
private void updateHeight(Node n) {
n.height = 1 + Math.max(height(n.left), height(n.right));
}
private int height(Node n) {
return n == null ? -1 : n.height;
}
public int getBalance(Node n) {
return (n == null) ? 0 : height(n.right) - height(n.left);
}
}