/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode() {}
* TreeNode(int val) { this.val = val; }
* TreeNode(int val, TreeNode left, TreeNode right) {
* this.val = val;
* this.left = left;
* this.right = right;
* }
* }
*/
class Solution {
public TreeNode invertTree(TreeNode root)
{
if(root == null)
return root;
TreeNode t = root.left;
root.left = root.right;
root.right = t;
if (root.left != null)
invertTree(root.left);
if (root.right != null)
invertTree(root.right);
return root;
}
}