power-of-three.md

<p>Given an integer, write a function to determine if it is a power of three.</p>

<p><b>Example 1:</b></p>

<pre>
<strong>Input:</strong> 27
<strong>Output:</strong> true
</pre>

<p><b>Example 2:</b></p>

<pre>
<strong>Input:</strong> 0
<strong>Output:</strong> false</pre>

<p><b>Example 3:</b></p>

<pre>
<strong>Input:</strong> 9
<strong>Output:</strong> true</pre>

<p><b>Example 4:</b></p>

<pre>
<strong>Input:</strong> 45
<strong>Output:</strong> false</pre>

<p><b>Follow up:</b><br />
Could you do it without using any loop / recursion?</p>