1071-greatest-common-divisor-of-strings

1071. Greatest Common Divisor of Strings (Easy) (https://leetcode.com/problems/greatest-common-divisor-of-strings/)

For two strings s and t, we say “t divides s” if and only if s = 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. Constraints: 1 <= str1.length, str2.length <= 1000 str1 and str2 consist of English uppercase letters.

function gcdOfStrings(str1: string, str2: string): string {
  if (str1 + str2 !== str2 + str1)
    return ''
  return str1.slice(0, gcd(str1.length, str2.length))
}
 
// Алгоритм Евклида
function gcd(a: number, b: number) {
  if (b === 0) {
    return a
  }
  return gcd(b, a % b)
}
 
// Local check:
console.log(gcdOfStrings('ABCABC', 'ABC'))
console.log(gcdOfStrings('ABABAB', 'ABAB'))
console.log(gcdOfStrings('LEET', 'CODE'))

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: ""

string