ugly-number.md

<p>Write a program to check whether a given number is an ugly number.</p>

<p>Ugly numbers are <strong>positive numbers</strong> whose prime factors only include <code>2, 3, 5</code>.</p>

<p><strong>Example 1:</strong></p>

<pre>
<strong>Input:</strong> 6
<strong>Output:</strong> true
<strong>Explanation: </strong>6 = 2 &times;&nbsp;3</pre>

<p><strong>Example 2:</strong></p>

<pre>
<strong>Input:</strong> 8
<strong>Output:</strong> true
<strong>Explanation: </strong>8 = 2 &times; 2 &times;&nbsp;2
</pre>

<p><strong>Example 3:</strong></p>

<pre>
<strong>Input:</strong> 14
<strong>Output:</strong> false 
<strong>Explanation: </strong><code>14</code> is not ugly since it includes another prime factor <code>7</code>.
</pre>

<p><strong>Note:</strong></p>

<ol>
	<li><code>1</code> is typically treated as an ugly number.</li>
	<li>Input is within the 32-bit signed integer range:&nbsp;[&minus;2<sup>31</sup>,&nbsp; 2<sup>31&nbsp;</sup>&minus; 1].</li>
</ol>