Given a non-empty binary tree, return the average value of the nodes on each level in the form of an array.

**Example 1:**

Input:3 / \ 9 20 / \ 15 7Output:[3, 14.5, 11]Explanation:The average value of nodes on level 0 is 3, on level 1 is 14.5, and on level 2 is 11. Hence return [3, 14.5, 11].

**Note:**

- The range of node’s value is in the range of 32-bit signed integer.

### Solution (Runtime: 6 ms)

```
/**
* 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> rst = new ArrayList<>();
if(root == null) {
return rst;
}
Queue<TreeNode> queue = new LinkedList<>();
queue.offer(root);
while(!queue.isEmpty()) {
int size = queue.size();
double sum = 0;
for(int i = 0; i < size; i++) {
TreeNode curr = queue.poll();
sum += curr.val;
if(curr.left != null) {
queue.offer(curr.left);
}
if(curr.right != null) {
queue.offer(curr.right);
}
}
rst.add(sum / size);
}
return rst;
}
}
```

Thanks for reading. I hope you learned something interesting about React!

If you found this article useful, please share it with others. Donâ€™t forget to subscribe to get notified for the upcoming articles.