For two strings s and t, we say "t divides s" if and only if s = t + ... + t (t concatenated with itself 1 or more times)
Given two strings str1 and str2, return the largest string x such that x divides both str1 and str2.
Example 1:
Input: str1 = "ABCABC", str2 = "ABC" Output: "ABC"
Example 2:
Input: str1 = "ABABAB", str2 = "ABAB" Output: "AB"
Example 3:
Input: str1 = "LEET", str2 = "CODE" Output: ""
Example 4:
Input: str1 = "ABCDEF", str2 = "ABC" Output: ""
Constraints:
1 <= str1.length <= 10001 <= str2.length <= 1000str1andstr2consist of English uppercase letters.