Base 7

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

        sign = "-" if num < 0 else ""
        num = abs(num)
        digits = []
        while num > 0:
            digits.append(str(num % 7))
            num //= 7
        return sign + "".join(reversed(digits))

class Solution {
public:
    string convertToBase7(int num) {
        if (num == 0) {
            return "0";
        }

        string sign = num < 0 ? "-" : "";
        int value = abs(num);
        string digits;
        while (value > 0) {
            digits.push_back(static_cast<char>('0' + value % 7));
            value /= 7;
        }
        reverse(digits.begin(), digits.end());
        return sign + digits;
    }
};

function convertToBase7(num: number): string {
    if (num === 0) {
        return "0";
    }

    const sign = num < 0 ? "-" : "";
    let value = Math.abs(num);
    const digits: string[] = [];
    while (value > 0) {
        digits.push(String(value % 7));
        value = Math.floor(value / 7);
    }
    digits.reverse();
    return sign + digits.join("");
}