1071. Greatest Common Divisor of Strings.cpp

// 1071. Greatest Common Divisor of Strings
// Easy
// Topics
// Companies
// Hint
// 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: ""
 

// Constraints:

// 1 <= str1.length, str2.length <= 1000
// str1 and str2 consist of English uppercase letters.


class Solution {
public:
    string gcdOfStrings(string str1, string str2) {
        int n1=str1.size();
        int n2=str2.size();
        if(str1+str2 != str2+str1){
            return "";
        }
            return str1.substr(0,gcd(n1,n2));        
    }
};