LeetCode----Balanced Binary Tree

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 depth of the two subtrees of every node never differ by more than 1.

分析：

判断一棵树是否是平衡二叉树。

使用递归判断，在递归中需要做到两点，第一点，如果当前子树不满足平衡二叉树的性质，而返回False；第二点，如果当前子树满足平衡二叉树，则返回当前子树的高度。

另外，如果树为空，也是平衡二叉树。

代码：

# 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
"""
isAVL = self.traverse(root)
return True if isAVL else False

def traverse(self, root):
if root:
l_high = self.traverse(root.left)
r_high = self.traverse(root.right)
if not l_high or not r_high:
return False
if abs(l_high - r_high) > 1:
return False
return max(l_high, r_high) + 1
return 1