LeetCode in Kotlin
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 <= 1000str1andstr2consist of English uppercase letters.
Solution
class Solution {
fun gcdOfStrings(str1: String?, str2: String?): String {
if (str1 == null || str2 == null) {
return ""
}
if (str1 == str2) {
return str1
}
val m = str1.length
val n = str2.length
if (m > n && str1.substring(0, n) == str2) {
return gcdOfStrings(str1.substring(n), str2)
}
return if (n > m && str2.substring(0, m) == str1) {
gcdOfStrings(str2.substring(m), str1)
} else ""
}
}