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：用递归的方法来判断，如果左子树和右子树均为平衡二叉树且左子树和右子树的高度差小于等于1，那么该树是平衡二叉树。代码如下：
class Solution { public: bool isBalanced(TreeNode *root) { if(root == NULL) return true; return isBalanced(root->left) && isBalanced(root->right) && abs(get_depth(root->left) - get_depth(root->right)) <= 1; } int get_depth(TreeNode *root){ if(root == NULL) return 0; return max(get_depth(root->left), get_depth(root->right)) + 1; } };
原文：http://www.cnblogs.com/Kai-Xing/p/4191411.html