2. 1071. Greatest Common Divisor of Strings

class Solution {
    public String gcdOfStrings(String str1, String str2) {
        if((str1+str2).equals(str2+str1)){
            int len1 = str1.length();
            int len2 = str2.length();
            int gcdOfNum = gcd(len1,len2);
            String ans = str1.substring(0,gcdOfNum);
            return ans;
        }
        return "";
        
    }

    private int gcd(int a,int b){
        if(b==0){
            return a;
        }

        return gcd(b,a%b);
    }
}