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 res;
        
        int abs_num = abs(num);
        while(abs_num > 0){
            string temp = to_string(abs_num % 7);
            res = temp + res;
            abs_num /= 7;
        }
        return num >= 0 ? res : '-' + res;
    }
};