Ugly Number
<p>An <strong>ugly number</strong> is a <em>positive</em> integer which does not have a prime factor other than 2, 3, and 5.</p>

<p>Given an integer <code>n</code>, return <code>true</code> <em>if</em> <code>n</code> <em>is an <strong>ugly number</strong></em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

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

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> n = 1
<strong>Output:</strong> true
<strong>Explanation:</strong> 1 has no prime factors.
</pre>

<p><strong class="example">Example 3:</strong></p>

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

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

<ul>
	<li><code>-2<sup>31</sup> &lt;= n &lt;= 2<sup>31</sup> - 1</code></li>
</ul>
Math
class Solution {
public:
    bool isUgly(int n) {
        if (n < 1) return false;
        while (n % 2 == 0) {
            n /= 2;
        }
        while (n % 3 == 0) {
            n /= 3;
        }
        while (n % 5 == 0) {
            n /= 5;
        }
        return n == 1;
    }
};