Python - 递归查找父树

Question

我有一个二叉树，只有self._root和self._nodes。无论如何我可以弄清楚如何通过构造函数找到当前树的父树？

class BinaryTree:
    """
    - If _root is None, then _nodes is empty and _parent_tree is None
    - nodes is allowed to contain empty nodes
    - if _parent_tree is not empty, then self is in _parent_tree._nodes
    """
    def __init__(self, root, nodes):
        """Initialize a new BinaryTree.
        @type self: BinaryTree
        @type root: object
        @type nodes: list[BinaryTree]
        @rtype: None
        """
        self._root = root
        self._nodes = nodes
        self._parent_tree = None


        """Implement _parent_tree"""

        if self._root is not None:
            """implement"""
        else:
            pass

说实话，我不知道如何开始这个。如何在不构造此对象的情况下知道任何其他BinaryTree对象。我会以递归方式查看什么？我不太可能透过这个BinaryTree

Answer 1

以下应该对你有用：

class BinaryTree:
  def __init__(self, root, nodes):
    self._root = root
    self._nodes = nodes
    self._parent_tree = None

    if self._root is not None:
        for node in self._nodes:
            if node is not None:
                node._parent_tree = self
    else:
        pass