110. 平衡二叉树

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def isBalanced(self, root: Optional[TreeNode]) -> bool:
        if self.calheight(root) != -1:
            return True
        else:
            return False

    def calheight(self, root):
        if not root:
            return 0
        if (left_height := self.calheight(root.left)) == -1:
            return -1
        if (right_height := self.calheight(root.right)) == -1:
            return -1
        if abs(left_height - right_height) > 1:
            return -1
        else:
            return max(left_height, right_height) + 1