# Pending...

# Definition for a binary tree node.

# class TreeNode(object):

# def __init__(self, x):

# self.val = x

# self.left = None

# self.right = None

class Solution(object):

def isBalanced(self, root):

"""

:type root: TreeNode

:rtype: bool

"""

def height(node):

if node is None:

return 0

else:

return 1+max(height(node.left), height(node.right))

def balance(node):

if node is None:

return result

else:

if node.left:

balance(node.left)

if node.right:

balance(node.right)

if abs(height(node.left)-height(node.right)) <= 1:

return True

else:

return False

if not root:

return True

return balance(root)