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637. Average of Levels in Binary Tree

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题目

原题在此

解析

标准的level order traversal, 没啥好讲的.

代码

c++

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/**
 * 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:
    vector<double> averageOfLevels(TreeNode* root) {
        if(!root) return {};
        vector<double> res;
        queue<TreeNode*> q;
        q.push(root);
        while(!q.empty()) {
            int n = q.size();
            long long sum = 0;
            for(int i = 0; i < n; ++i) {
                TreeNode* tmp = q.front();
                q.pop();
                sum += tmp->val;
                if(tmp->left) q.push(tmp->left);
                if(tmp->right) q.push(tmp->right);
            }
            res.push_back(double(sum) / double(n));
        }
        return res;
    }
};