<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 {
public:
    string convertToBase7(int num) {
        if(num == 0)
        {
            return "0";
        }
        string ans = "";
        int flag = 0;
        if(num < 0)
        {
            num = num*(-1);
            flag = 1;
        }
        while(num != 0)
        {
            int modu = num%7;
            ans += (char)modu + '0';
            num -= modu;
            num /= 7;
        }
        reverse(ans.begin(), ans.end());
        if(flag == 1)
        {
            ans = '-'+ans;
        }
        return ans;
    }
};
7400