Fixes: AVL Trees #160

AVLTrees.java

@@ -0,0 +1,136 @@
+import javax.xml.crypto.Data;
+
+// package AVL Trees;
+
+public class AVLTrees {
+    static class Node {
+        int data;
+        int height; // For Balanced Facor
+        Node left;
+        Node right;
+
+        Node(int data) {
+            this.data = data;
+            height = 1;
+        }
+    }
+
+    public static Node root;
+
+    public static int height(Node root) {
+        if (root == null) {
+            return 0;
+        }
+        return root.height;
+    }
+
+    //right rotate subtree rotated with y
+    public static Node rightRotate(Node y) {
+        Node x = y.left;
+        Node T2 = x.right;
+
+        //Perform Rottion
+        x.right = y;
+        y.left  = T2;
+
+        //Update height
+        y.height = Math.max(height(y.left) , height(y.right)) + 1;
+        x.height = Math.max(height(x.left) , height(x.right)) + 1;
+
+        return x;
+    }
+
+    //left rotate subtree rotated with x
+    public static Node leftRotate(Node x) {
+        Node y = x.right;
+        Node T2 = y.left;
+
+        //Perform Rottion
+        y.left = x;
+        x.right = T2;
+
+        //Update height
+        x.height = Math.max(height(x.left) , height(x.right)) + 1;
+        y.height = Math.max(height(y.left) , height(y.right)) + 1;
+
+        return y;
+    }
+
+    //Get Balnaced Factor of Node
+    public static int getbalance(Node root) {
+        if (root == null) {
+            return 0;
+        }
+        return height(root.left) - height(root.right);
+    }
+
+    public static Node insert(Node root, int key) {
+        if (root == null) {
+            return new Node(key);
+        }
+        if (key < root.data) {
+            root.left = insert(root.left, key);
+        } else if (key > root.data) {
+            root.right = insert(root.right, key);
+        } else {
+            return root; // Duplicate Keys Not Allowed
+        }
+
+        // Update Root height
+        root.height = 1 + Math.max(height(root.left), height(root.right));
+
+        // Get root's Balance Factor
+        int bf = getbalance(root);
+
+        //Left Left Case
+        if (bf > 1 && key < root.left.data) {
+            return rightRotate(root);
+        }
+
+        //Right Right Case
+        if (bf < -1 && key > root.right.data) {
+            return leftRotate(root);
+        }
+
+        //Left Right Case
+        if (bf > 1 && key > root.left.data) {
+            root.left = leftRotate(root.left);
+            return rightRotate(root);
+        }
+
+        //Right Left Case
+        if (bf < -1 && key < root.right.data) {
+            root.right = rightRotate(root.right);
+            return leftRotate(root);
+        }
+
+        return root;
+    }
+    public static void preOrder(Node root) {
+        if (root == null) {
+            return;
+        }
+
+        System.out.print(root.data + " ");
+        preOrder(root.left);
+        preOrder(root.right);
+    }
+
+    public static void main(String[] args) {
+        root = insert(root , 10);
+        root = insert(root , 20);
+        root = insert(root , 30);
+        root = insert(root , 40);
+        root = insert(root , 50);
+        root = insert(root , 25);
+
+        //    AVL  TREES
+        //       30
+        //      /  \
+        //     20   40
+        //    / \    \
+        //   10 25   50   
+
+        preOrder(root);
+    }
+}