count-complete-tree-nodes.md

<p>Given a <b>complete</b> binary tree, count the number of nodes.</p>

<p><b>Note: </b></p>

<p><b><u>Definition of a complete binary tree from <a href="http://en.wikipedia.org/wiki/Binary_tree#Types_of_binary_trees" target="_blank">Wikipedia</a>:</u></b><br />
In a complete binary tree every level, except possibly the last, is completely filled, and all nodes in the last level are as far left as possible. It can have between 1 and 2<sup>h</sup> nodes inclusive at the last level h.</p>

<p><strong>Example:</strong></p>

<pre>
<strong>Input:</strong> 
    1
   / \
  2   3
 / \  /
4  5 6

<strong>Output:</strong> 6</pre>