Greatest Common Divisor of Strings

🧠 Before you code — what pattern fits?

For two strings s and t, we say "t divides s" if s = t + t + … + t (t concatenated one or more times).

Given two strings str1 and str2, return the largest string x such that x divides both str1 and str2.

gcd("ABCABC","ABC") → "ABC"

gcd("ABABAB","ABAB") → "AB"

gcd("LEET","CODE") → ""

🎬 Video explanation · NeetCodeIO

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