637. 二叉树的层平均值

川长思鸟来 2023-02-18 08:11 18阅读 0赞

# 题目来源 #

[637. 二叉树的层平均值][637.]

# 题目描述 #

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poaXpoZW5nZ3Vhbg_size_16_color_FFFFFF_t_70]

# 题目解析 #

## 层次遍历 ##

/**
     * Definition for a binary tree node.
     * public class TreeNode {
     *     int val;
     *     TreeNode left;
     *     TreeNode right;
     *     TreeNode(int x) { val = x; }
     * }
     */
    class Solution {
        
        public List<Double> averageOfLevels(TreeNode root) {
        
            List<Double> list = new LinkedList<>();
            if (root == null){
        
                return list;
            }
    
            LinkedList<TreeNode> queue = new LinkedList<>();
            queue.offer(root);
            while (!queue.isEmpty()){
        
                int size = queue.size();
                double sum = 0;
                int count = 0;
                for (int i = 0; i < size; i++){
        
                    TreeNode pop = queue.pop();
                    sum += pop.val;
                    count++;
                    if (pop.left != null){
        
                        queue.offer(pop.left);
                    }
                    if (pop.right != null){
        
                        queue.offer(pop.right);
                    }
                }
    
                if (count != 0){
        
                    list.add(sum / count);
                }
            }
    
            return list;
        }
    }

![在这里插入图片描述][20200616155553648.png]

[637.]: https://leetcode-cn.com/problems/average-of-levels-in-binary-tree/
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poaXpoZW5nZ3Vhbg_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20200616155457960.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poaXpoZW5nZ3Vhbg==,size_16,color_FFFFFF,t_70
[20200616155553648.png]: https://img-blog.csdnimg.cn/20200616155553648.png