Leetcode 504. Base 7

Problem

Given an integer num, return a string of its base 7 representation.

Algorithm

Distinguish between positive and negative values, then store the remainders in reverse order after dividing by 7.

Code

class Solution:
    def convertToBase7(self, num: int) -> str:
        if not num:
            return "0"

        sign = 0
        if num < 0:
            num = -num
            sign = -1
        
        ans = ""
        while num:
            ans = str(num % 7) + ans 
            num //= 7
        
        if sign < 0:
            ans = "-" + ans

        return ans