226. Invert Binary Tree

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