2025-07-29 17:50:01 +0000 UTC

class Solution:
    def convertToBase7(self, num: int) -> str:
        if num > -7 and num < 7:
            return str(num)
        res_arr = []
        sign = ""
        if num < 0:
            sign = "-"
            num = -num
        while num:
            res_arr.append(str(num % 7))
            num //= 7
        res = sign + "".join(reversed(res_arr))
        return res