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.

判断一个二叉树是否为平衡二叉树，只需判断就好了，所以递归求两支深度就好，代码如下：

/** * Definition for binary tree * struct TreeNode { *     int val; *     TreeNode *left; *     TreeNode *right; *     TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */class Solution {      bool balanced = true;      int height(TreeNode *root) {                if (root == NULL) {              return 0;          }          int lH = height(root->left) + 1;          int lL = height(root->right) + 1;          if (abs(lH - lL) > 1) {              balanced = false;          }          return lH > lL ? lH : lL;      }  public:      bool isBalanced(TreeNode *root) {          balanced = true;          height(root);          return balanced;      }  };