504. Base 7

Given an integer, return its base 7 string representation.

Example 1:

Input: 100
Output: "202"

Example 2:

Input: -7
Output: "-10"

Note: The input will be in range of [-1e7, 1e7].

class Solution {
public:
    string convertToBase7(int num) {
        if (num == 0) 
return "0";
        string sign = "";
        if (num < 0) {
            num = abs(num);
            sign = "-";
        }
        string result = "";


        while (num != 0) {
            result = to_string(num%7) + result;


            num = num / 7;
        }
        return sign + result;
    }
};