struct TreeNode* Mirror(struct TreeNode* pRoot ) {
    if(!pRoot) return pRoot;
    struct TreeNode* temp=pRoot->left;
    pRoot->left=pRoot->right;
    pRoot->right=temp;
    if(pRoot->left)Mirror(pRoot->left);
    if(pRoot->right)Mirror(pRoot->right);
    return pRoot;
}