Solution: Greatest Common Divisor of Strings

Statement

For two strings s and t, we say that t divides s if and only if s can be formed by concatenating one or more copies of t together (i.e., s = t + t + ... + t).

Given two strings str1 and str2, return the largest string x such that x divides both str1 and str2. If no such string exists, return an empty string.

Constraints:

• $1 \leq$ str1.length, str2.length $\leq 1000$

• str1 and str2 consist of English uppercase letters. ...

Solution