0637. Average of Levels in Binary Tree

https://leetcode.com/problems/average-of-levels-in-binary-tree

Description

Given the root of a binary tree, return the average value of the nodes on each level in the form of an array. Answers within 10-5 of the actual answer will be accepted. Example 1:

**Input:** root = [3,9,20,null,null,15,7]
**Output:** [3.00000,14.50000,11.00000]
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].

Example 2:

**Input:** root = [3,9,20,15,7]
**Output:** [3.00000,14.50000,11.00000]

Constraints:

• The number of nodes in the tree is in the range [1, 104].

• -231 <= Node.val <= 231 - 1

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