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;
    }
}