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.
关键点:1)树主要就是根节点为空,叶子节点,一条边为空的情况需要讨论。
2)平衡树需要多讨论两个子节点的高度差是否大于1,以及子节点是否是平衡树。
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* Definition for binary tree原文地址:http://blog.csdn.net/shahongzhou/article/details/40357833