template<class T> 
void MirroTree(TreeNode<T> * root) 
{ 
  if (root == NULL) 
    return; 
  if (root->_left == NULL && root->_right == NULL) 
    return; 
  else 
  { 
    TreeNode<T>* temp = root->_left; 
    root->_left = root->_right; 
    root->_right = temp; 
  } 
  MirroTree(root->_left); 
  MirroTree(root->_right); 
} 

template<class T> 
void MirroTree_NoR(TreeNode<T>* root) 
{ 
  stack<TreeNode<T>*> s; 
  s.push(root); 
  while (s.size()) 
  { 
    TreeNode<T>* Top = s.top(); 
    if (Top->_left != NULL || Top->_right != NULL) 
    { 
      TreeNode<T>* temp = Top->_left; 
      Top->_left = Top->_right; 
      Top->_right = temp; 
    } 
    if (Top->_left != NULL) 
      s.push(Top->_left); 
    if (Top->_right != NULL) 
      s.push(Top->_right); 
  } 
}