Leetcode: Balanced Binary Tree

Get idea from Code Ganker′s Solution

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Question

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.

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Analysis

We need to return the depth of each node and whether it is balanced.

The tricky here is to set -1 if subtree is not balanced, otherwise return depth of root of subtree.

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Other′s Solution

# Definition for a binary tree node.# class TreeNode:#     def __init__(self, x):#         self.val = x#         self.left = None#         self.right = Noneclass Solution:    # @param {TreeNode} root    # @return {boolean}    def isBalanced(self, root):        return self.search(root)>=0    def search(self,root):        if root==None:            return 0        hl = self.search(root.left)        hr = self.search(root.right)        if hl>=0 and hr>=0 and abs(hl-hr)<=1:            return 1 + max(hl,hr)        else:            return -1