110. Balanced Binary Tree

[chengchengxu15]

https://leetcode.com/problems/balanced-binary-tree/

Given a binary tree, determine if it is height-balanced.

For this problem, a height-balanced binary tree is defined as:

a binary tree in which the left and right subtrees of every node differ in height by no more than 1.

[chengchengxu15]

方法一： 递归 recursive: 检测每次左右两边是否是Binary Tree，是的话返回高度+1

class Solution:
    def isBalanced(self, root: Optional[TreeNode]) -> bool:
        def isbalanced_height(root):
            if root == None:
                return 0
            left_height = isbalanced_height(root.left)
            right_height = isbalanced_height(root.right)
            if left_height == -1 or right_height == -1 or abs(left_height - right_height)>1:
                return -1
            return max(left_height,right_height) +1 

        return isbalanced_height(root)>=0 

[chengchengxu15]

方法二： 检查每一个检点左右两个的高度是否满足条件。有点蠢。。。