greatest_common_divisor_of_strings.py

import math
class Solution:
    def gcdOfStrings(self, str1: str, str2: str) -> str:
        
        if str1 + str2 != str2 + str1:
            return ""
        
        gcd_length = math.gcd(len(str1), len(str2))
        return str1[:gcd_length]