Update and rename 3-set/java/implementations/treeset to 3-set/java/imple...

3-set/java/implementations/treeset/AVLTree.java

@@ -0,0 +1,126 @@
+
+public class AVLTree {	
+
+	//Function to compute height of a tree
+	public static int height(TreeNode current){
+		if(current == null)
+			return 0;
+		return current.height;
+	}
+
+	 /*    y                                   x
+	      / \                                 / \ 
+	     x  leaf3       --------->        leaf1  y
+	    / \                                    /  \
+	   /   \                                  /    \
+	 leaf1 leaf2                            leaf2  leaf3    */
+	/*                 Right Rotate                 */
+	public static TreeNode rightrotate(TreeNode y){
+		TreeNode x = y.left;
+		TreeNode leaf = x.right;
+
+		x.right = y;
+		y.left = leaf;
+
+		y.height = Math.max(height(y.left), height(y.right)) + 1;
+		x.height = Math.max(height(x.left), height(x.right)) + 1;
+
+		return x;
+	}
+	 /*    y                                   x
+          / \                                 / \ 
+         x  leaf3       <---------        leaf1  y
+        / \                                    /  \
+       /   \                                  /    \
+    leaf1 leaf2                            leaf2  leaf3    */
+     /*                 Left Rotate                 */
+
+	public static TreeNode leftrotate(TreeNode x){
+		TreeNode y = x.right;
+		TreeNode leaf = y.left;
+
+		y.left = x;
+		x.right = leaf;
+
+		y.height = Math.max(height(y.left), height(y.right)) + 1;
+		x.height = Math.max(height(x.left), height(x.right)) + 1;
+
+		return y;
+	}
+
+
+	//Get Balance factor of TreeNode current
+	public static int getBalance(TreeNode current){
+		if(current == null)
+			return 0;
+		return height(current.left) - height(current.right);
+	}
+
+	//Performs insert operation
+	public static TreeNode insert(TreeNode current, int key){
+
+
+		//Condition for adding first node
+		if(current == null)
+			return new TreeNode(key);
+
+		//Normal BST insertion
+		if(key < current.key)
+			current.left = insert(current.left, key);
+		else
+			current.right = insert(current.right, key);
+
+		//Updating height of the ancestor node
+		current.height = Math.max(height(current.left), height(current.right)) + 1;
+
+		//getting balance factor to check if the node is unbalanced
+		int balance = getBalance(current);
+
+		//4 conditions of unbalancing
+		if(balance > 1 && key < current.left.key)
+			return rightrotate(current);
+		if(balance < -1 && key > current.right.key)
+			return leftrotate(current);
+		if(balance > 1 && key > current.left.key)
+		{
+			current.left = leftrotate(current.left);
+			return rightrotate(current);
+		}
+
+		if(balance < -1 && key < current.right.key)
+		{
+			current.right = rightrotate(current.right);
+			return leftrotate(current);
+		}
+
+		return current;
+	}
+
+	//Tree traversal preOrder
+	public static void preOrder(TreeNode root){
+		if(root != null)
+		{
+			System.out.println(root.key);
+			preOrder(root.left);
+
+			preOrder(root.right);
+		}
+	}
+
+	public static void main(String args[])
+	{
+		  TreeNode root = null;
+		  root = insert(root, 10);
+		  root = insert(root, 20);
+		  root = insert(root, 30);
+		  root = insert(root, 40);
+		  root = insert(root, 50);
+		  root = insert(root, 25);
+		  preOrder(root);
+
+	}
+
+
+
+
+}