【leetcode】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.

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题解：一A的题，写一个递归函数height计算树的高度，然后递归实现isBalance函数即可。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 {
public:
    bool isBalanced(TreeNode *root) {
        if(root == NULL)
            return true;
        if(abs(height(root->left)-height(root->right)) > 1)
            return false;
        return isBalanced(root->left) && isBalanced(root->right);
    }
    int height(TreeNode *root){
        if(root == NULL)
            return 0;
        int left = height(root->left);
        int right = height(root->right);
        return 1+(left>right?left:right);
    }
};