Create AVLTree.js

Author: vishantrathi

AVLTree.js

@@ -0,0 +1,80 @@
+class Node {
+    constructor(data) {
+        this.data = data;
+        this.left = null;
+        this.right = null;
+        this.height = 1;
+    }
+}
+
+class AVLTree {
+    getHeight(node) {
+        return node ? node.height : 0;
+    }
+
+    getBalance(node) {
+        return node ? this.getHeight(node.left) - this.getHeight(node.right) : 0;
+    }
+
+    rightRotate(y) {
+        let x = y.left;
+        let T2 = x.right;
+        x.right = y;
+        y.left = T2;
+        y.height = Math.max(this.getHeight(y.left), this.getHeight(y.right)) + 1;
+        x.height = Math.max(this.getHeight(x.left), this.getHeight(x.right)) + 1;
+        return x;
+    }
+
+    leftRotate(x) {
+        let y = x.right;
+        let T2 = y.left;
+        y.left = x;
+        x.right = T2;
+        x.height = Math.max(this.getHeight(x.left), this.getHeight(x.right)) + 1;
+        y.height = Math.max(this.getHeight(y.left), this.getHeight(y.right)) + 1;
+        return y;
+    }
+
+    insert(node, data) {
+        if (!node) return new Node(data);
+        if (data < node.data) node.left = this.insert(node.left, data);
+        else if (data > node.data) node.right = this.insert(node.right, data);
+        else return node;
+
+        node.height = 1 + Math.max(this.getHeight(node.left), this.getHeight(node.right));
+        let balance = this.getBalance(node);
+
+        if (balance > 1 && data < node.left.data) return this.rightRotate(node);
+        if (balance < -1 && data > node.right.data) return this.leftRotate(node);
+        if (balance > 1 && data > node.left.data) {
+            node.left = this.leftRotate(node.left);
+            return this.rightRotate(node);
+        }
+        if (balance < -1 && data < node.right.data) {
+            node.right = this.rightRotate(node.right);
+            return this.leftRotate(node);
+        }
+        return node;
+    }
+
+    preOrder(node) {
+        if (node !== null) {
+            console.log(node.data);
+            this.preOrder(node.left);
+            this.preOrder(node.right);
+        }
+    }
+}
+
+// Example usage
+let tree = new AVLTree();
+let root = null;
+root = tree.insert(root, 10);
+root = tree.insert(root, 20);
+root = tree.insert(root, 30);
+root = tree.insert(root, 40);
+root = tree.insert(root, 50);
+root = tree.insert(root, 25);
+console.log("Preorder traversal of the constructed AVL tree is:");
+tree.preOrder(root);