DoubleTree

package tree;

public class DoubleTree {

	/**
	 * Write a program that converts a given tree to its Double tree. 
	 * To create Double tree of the given tree, create a new duplicate for each node, 
	 * and insert the duplicate as the left child of the original node.

So the tree…

    2
   / \
  1   3
is changed to…

       2
      / \
     2   3
    /   /
   1   3
  /
 1
	 * @param args
	 */
	public static void doubleTree(TreeNode root){
		TreeNode cur = root;
		if(cur==null) return;
		doubleTree(cur.left);
		doubleTree(cur.right);
		TreeNode newNode = new TreeNode(cur.value);
		newNode.left = cur.left;
		cur.left = newNode;
	}
	public static void print(TreeNode root){
		if(root==null) return;
		System.out.print(root.value+" ");
		print(root.left);
		print(root.right);
	}
	public static void main(String[] args) {
		
		TreeNode root = new TreeNode(2);
		root.left = new TreeNode(1);
		root.right = new TreeNode(3);
		print(root);
		doubleTree(root);
		System.out.println();
		print(root);

	}

}