获取玫瑰树中节点的父节点

class TreeNode:
    def __init__(self, value):
        self.value = value
        self.left = None
        self.right = None
        self.parent = None  # 指向父节点的引用

class BinaryTree:
    def __init__(self):
        self.root = None

    def add_node(self, value, parent_value=None):
        new_node = TreeNode(value)
        if parent_value is None:
            self.root = new_node
        else:
            parent_node = self._find_node(parent_value, self.root)
            if parent_node:
                if parent_node.left is None:
                    parent_node.left = new_node
                elif parent_node.right is None:
                    parent_node.right = new_node
                new_node.parent = parent_node  # 设置新节点的父节点引用
            else:
                raise ValueError("Parent node not found.")

    def _find_node(self, value, current_node):
        if current_node is None or current_node.value == value:
            return current_node
        left_result = self._find_node(value, current_node.left)
        if left_result:
            return left_result
        return self._find_node(value, current_node.right)

    def get_parent(self, value):
        node = self._find_node(value, self.root)
        if node and node.parent:
            return node.parent.value
        return None

# 使用示例
tree = BinaryTree()
tree.add_node(1)  # 添加根节点
tree.add_node(2, 1)  # 添加值为2的节点，父节点为1
tree.add_node(3, 1)  # 添加值为3的节点，父节点为1
print(tree.get_parent(2))  # 输出: 1