1.题目：
2思路：
3.代码：
struct TreeNode
{
int val;
TreeNode *left;
TreeNode *right;
}
class Solution
{
public:
void Mirror(TreeNode *pRoot)
{
if((pRoot == NULL)||(pRoot->left==NULL)||(pRoot->right==NULL))
return;
//交换根节点 的左右节点
TreeNode *pTemp = pRoot->left;
pRoot->left = pRoot->right;
pRoot->right = pTemp;
//递归左子树
if(pRoot->left)
Mirror(pRoot->left);
//递归右子树
if(pRoot->right)
Mirror(pRoot->right);
}
};