LeetCode637. 二叉树的层平均值

题目

 1 class Solution {
 2 public:
 3     vector<double>ans;
 4     vector<double> averageOfLevels(TreeNode* root) {
 5         if(!root) return ans;
 6         queue<TreeNode*>q;
 7         q.push(root);
 8         while(!q.empty()){
 9             int num = q.size();double sum = 0;
10             for(int i = 0;i < num;i++){
11                 TreeNode* node = q.front();q.pop();
12                 sum += node->val;
13                 if(node->left!=NULL) q.push(node->left);
14                 if(node->right!=NULL) q.push(node->right);
15             }
16             ans.push_back(sum/num);
17         }
18         return ans;
19     }
20 };