Python TreeNode如何实现树的平衡

在Python中实现树的平衡可以通过实现平衡二叉树（AVL树）来实现。AVL树是一种自平衡二叉搜索树，即树的每个节点的左子树和右子树的高度差不超过1。

下面是一个简单的Python实现：

class TreeNode:
    def __init__(self, key):
        self.key = key
        self.left = None
        self.right = None
        self.height = 1

class AVLTree:
    def getHeight(self, node):
        if not node:
            return 0
        return node.height

    def getBalance(self, node):
        if not node:
            return 0
        return self.getHeight(node.left) - self.getHeight(node.right)

    def rotateRight(self, y):
        x = y.left
        T = x.right

        x.right = y
        y.left = T

        y.height = 1 + max(self.getHeight(y.left), self.getHeight(y.right))
        x.height = 1 + max(self.getHeight(x.left), self.getHeight(x.right))

        return x

    def rotateLeft(self, x):
        y = x.right
        T = y.left

        y.left = x
        x.right = T

        x.height = 1 + max(self.getHeight(x.left), self.getHeight(x.right))
        y.height = 1 + max(self.getHeight(y.left), self.getHeight(y.right))

        return y

    def insert(self, root, key):
        if not root:
            return TreeNode(key)
        elif key < root.key:
            root.left = self.insert(root.left, key)
        else:
            root.right = self.insert(root.right, key)

        root.height = 1 + max(self.getHeight(root.left), self.getHeight(root.right))

        balance = self.getBalance(root)

        if balance > 1 and key < root.left.key:
            return self.rotateRight(root)
        
        if balance < -1 and key > root.right.key:
            return self.rotateLeft(root)
        
        if balance > 1 and key > root.left.key:
            root.left = self.rotateLeft(root.left)
            return self.rotateRight(root)
        
        if balance < -1 and key < root.right.key:
            root.right = self.rotateRight(root.right)
            return self.rotateLeft(root)

        return root

使用上述代码可以创建一个AVL树，然后通过调用insert方法向树中插入新节点，保持树的平衡。