1071. Greatest Common Divisor of Strings

For two strings s and t, we say "t divides s" if and only if s = t + t + t + ... + 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: ""

Solution:

class Solution:

def gcdOfStrings(self, str1: str, str2: str) -> str:

l1, l2 = len(str1), len(str2)

  

def findGCD(l):

if l1 % l or l2 % l:

return False

f1, f2 = l1 // l, l2 // l

return str1==f1 * str1[:l] and str2 == f2 * str1[:l]

for l in range(min(l1, l2), 0, -1):

if findGCD(l):

return str1[:l]

return ""

Notes

assign and do multiple calculations using comma separated assignments % operator can be used without. == 0. as that is equivalent to False in an if condition

range() in python range(start, stop, step)