public class Solution
extends Object
1071 - Greatest Common Divisor of Strings\.
Easy
For two strings `s` and `t`, we say "`t` divides `s`" if and only if `s = t + ... + t` (i.e., `t` is concatenated with itself one 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:** ""
**Constraints:**
* `1 <= str1.length, str2.length <= 1000`
* `str1` and `str2` consist of English uppercase letters.