LeetCode 110. 平衡二叉树

LeetCode 110. 平衡二叉树

思路：
dfs

代码：

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    bool ans=true;
    bool isBalanced(TreeNode* root) {
        if(!root) return true;
        dfs(root);
        return ans; 
    }
    //返回深度
    int dfs(TreeNode* root){
        if (!root) return 0;
        int l=dfs(root->left), r=dfs(root->right);
        if(abs(l - r) > 1) ans=false;
        return max(l,r) + 1;
    }
};