二叉树的镜像定义：源二叉树 
    	    8
    	   /  \
    	  6   10
    	 / \  / \
    	5  7 9 11
    	镜像二叉树
    	    8
    	   /  \
    	  10   6
    	 / \  / \
    	11 9 7  5

 1 /*
 2 struct TreeNode {
 3     int val;
 4     struct TreeNode *left;
 5     struct TreeNode *right;
 6     TreeNode(int x) :
 7             val(x), left(NULL), right(NULL) {
 8     }
 9 };*/
10 class Solution {
11 public:
12     void Mirror(TreeNode *pRoot) {
13         if (pRoot == nullptr) {
14             return;
15         }
16         TreeNode *tmp = pRoot->left;
17         pRoot->left = pRoot->right;
18         pRoot->right = tmp;
19         Mirror(pRoot->left);
20         Mirror(pRoot->right);
21     }
22 };