/**

 public class TreeNode {

     int val = 0;

     TreeNode left = null;

     TreeNode right = null;

     public TreeNode(int val) {

         this.val = val;

     }

 }

 */

 //前序遍历这棵树的每个结点，如果遍历的节点有子结点，就交换其子结点，当交换完所有非叶子结点的左右子结点之后，就得到了树的镜像

 public class Solution {

     public void Mirror(TreeNode root) {

         if(root == null){

             return ;

         }

         if(root.left == null&&root.right == null){

             return;

         }

         TreeNode pTemp = root.left;

         root.left = root.right;

         root.right = pTemp;

         Mirror(root.left);

         Mirror(root.right);

     }

 }