void Exchange(TreeNode*& T)
{
    TreeNode* temp;
    if(T)
    {
        temp=T->left;
        T->left=T->right;
        T->right=temp;
        Exchange(T->left);
        Exchange(T->right);
    }
}
class Solution {
public:
 
    TreeNode* Mirror(TreeNode* pRoot) {
        Exchange(pRoot);
        return pRoot;
    }
};