leetcode 637. 二叉树的层平均值 c++

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637. 二叉树的层平均值

分析

• 二叉树的层遍历

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