<p>Given an integer <code>num</code>, return <em>a string of its <strong>base 7</strong> representation</em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<pre><strong>Input:</strong> num = 100
<strong>Output:</strong> "202"
</pre><p><strong class="example">Example 2:</strong></p>
<pre><strong>Input:</strong> num = -7
<strong>Output:</strong> "-10"
</pre>
<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>-10<sup>7</sup> &lt;= num &lt;= 10<sup>7</sup></code></li>
</ul>

class Solution:
    def convertToBase7(self, num: int) -> str:
        if num == 0:
            return "0"
        
        negative = num < 0
        num = abs(num)

        base = []
        while num > 0:
            base.append(str(num%7))
            num //= 7
        
        if negative:
            base.append("-")

        return "".join(base[::-1])

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