LeetCode 110. Balanced Binary Tree

题目

思路

递归遍历左右子树，找到高度。

代码

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution:
    def balance(self, root):
        if not root:
            return True, 0
        leftFlag, leftHigh = self.balance(root.left)
        rightFlag, rightHigh = self.balance(root.right)
        if not leftFlag or not rightFlag: return False, 0
        if abs(leftHigh - rightHigh) > 1: return False, 0
        return True, max(leftHigh, rightHigh) + 1
    def isBalanced(self, root):
        """
        :type root: TreeNode
        :rtype: bool
        """
        return self.balance(root)[0]