110. Balanced Binary Tree验证平衡二叉树

class Solution(object):
    def isBalanced(self, root):
        """
        :type root: TreeNode
        :rtype: bool
        """
        if not root:
            return True
        left = self.getHight(root.left)
        right = self.getHight(root.right)
        return abs(left-right) <= 1 and self.isBalanced(root.left) and self.isBalanced(root.right)
    def getHight(self,node):
        if not node:
            return 0
        return max(self.getHight(node.left),self.getHight(node.right))+1