110. 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.
这道题的思路比较简单就是每次求出左右子树的高度，然后相减，看看它们之间是否相差1，如果相差大于1，则return false，否则继续递归下去
代码如下：

/** * Definition for a binary tree node. * struct TreeNode { *     int val; *     TreeNode *left; *     TreeNode *right; *     TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */class Solution {public:    int height(TreeNode *root){        if(root==NULL)return 0;        else{            int l=height(root->left);            int r=height(root->right);            return 1+((l>r)?l:r);        }    }    bool isBalanced(TreeNode* root) {        if(root==NULL)return true;        else{            int l,r;            l=height(root->left);            r=height(root->right);            if(l>r+1||r>l+1){                return false;            }            else{                return isBalanced(root->left)&&isBalanced(root->right);            }        }    }};