ugly-number-ii.md

<p>Write a program to find the <code>n</code>-th ugly number.</p>

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

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

<pre>
<strong>Input:</strong> n = 10
<strong>Output:</strong> 12
<strong>Explanation: </strong><code>1, 2, 3, 4, 5, 6, 8, 9, 10, 12</code> is the sequence of the first <code>10</code> ugly numbers.</pre>

<p><strong>Note: </strong>&nbsp;</p>

<ol>
	<li><code>1</code> is typically treated as an ugly number.</li>
	<li><code>n</code> <b>does not exceed 1690</b>.</li>
</ol>