平衡二叉树

一、题目描述

　给定一个二叉树，判断它是否是高度平衡的二叉树

　本题中，一棵高度平衡二叉树定义为：一个二叉树每个节点 的左右两个子树的高度差的绝对值不超过1

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

class Solution:
    def isBalanced(self, root):
        """
        :type root: TreeNode
        :rtype: bool
        """
        if root == None:
            return True
        if abs(self.count(root.left)-self.count(root.right)) > 1:
            return False
        else:
            if self.isBalanced(root.left) and self.isBalanced(root.right):
                return True
            else:
                return False
        
    def count(self,tree):
            if tree == None:
                return 0
            else:
                return max(self.count(tree.left),self.count(tree.right))+1