Thousand Separator
<p>Given an integer <code>n</code>, add a dot (&quot;.&quot;) as the thousands separator and return it in string format.</p>

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

<pre>
<strong>Input:</strong> n = 987
<strong>Output:</strong> &quot;987&quot;
</pre>

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

<pre>
<strong>Input:</strong> n = 1234
<strong>Output:</strong> &quot;1.234&quot;
</pre>

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

<ul>
	<li><code>0 &lt;= n &lt;= 2<sup>31</sup> - 1</code></li>
</ul>
String
class Solution:
    def thousandSeparator(self, n: int) -> str:
        cnt = 0
        ans = []
        while 1:
            n, v = divmod(n, 10)
            ans.append(str(v))
            cnt += 1
            if n == 0:
                break
            if cnt == 3:
                ans.append('.')
                cnt = 0
        return ''.join(ans[::-1])
