力扣-637题二叉树的层平均值（C++）- 层序遍历

偏执的太偏执、 2022-09-02 03:54 129阅读 0赞

题目链接：[https://leetcode-cn.com/problems/average-of-levels-in-binary-tree/][https_leetcode-cn.com_problems_average-of-levels-in-binary-tree]  
题目如下：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwNDY3Njcw_size_16_color_FFFFFF_t_70]

/**
     * 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) {
        
        	//tip:
        	//但凡要对数字求和，使用长整型long，避免超出最大值
            vector<double> result;
            queue<TreeNode*> que;
            que.push(root);
    
            while(!que.empty()){
        
                long count=0;
                long sum=0;
                int size=que.size();
    
                while(size--){
        
                    TreeNode* node=que.front();
                    que.pop();
    
                    sum+=node->val;
                    count++;
    
                    if(node->left) que.push(node->left);
                    if(node->right) que.push(node->right);
                }
                result.push_back(sum*1.0/count);
            }
    
            return result;
        }
    };

[https_leetcode-cn.com_problems_average-of-levels-in-binary-tree]: https://leetcode-cn.com/problems/average-of-levels-in-binary-tree/
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwNDY3Njcw_size_16_color_FFFFFF_t_70]: /images/20220829/dfb75c7cfa2d4e399214effe36958a86.png