average-of-levels-in-binary-tree.md

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

<p><b>Example 1:</b><br />
<pre>
<b>Input:</b>
    3
   / \
  9  20
    /  \
   15   7
<b>Output:</b> [3, 14.5, 11]
<b>Explanation:</b>
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].
</pre>
</p>

<p><b>Note:</b><br>
<ol>
<li>The range of node's value is in the range of 32-bit signed integer.</li>
</ol>
</p>