// 非递归的算法，借助了栈
			Node* removeKey2(Node* node , Key key)
			{
				stack<Node*> stacknode;

				Node* newnode = node;

				while(newnode->key != key)
				{
					stacknode.push(newnode);
					if (key < newnode->key)
					{
						newnode = newnode->left;
					}else 
					{
						newnode = newnode->right;
					}
				}

				if (newnode->left == NULL)
				{
					stacknode.top()->left = newnode->right;
					delete newnode;
					count--;
					return node;
				}else if (newnode->right == NULL)
				{
					stacknode.top()->left = newnode->left;
					delete newnode;
					count--;
					return node;
				}else
				{
					Node* sucessor = new Node(mininum(newnode->right));
					sucessor->left = newnode->left;
					sucessor->right = removeMin(newnode->right);
					stacknode.top()->left = sucessor;
					delete newnode;
					count--;
					return node;
				}
			}