Leetcode-5076 Greatest Common Divisor of Strings(字符串的最大公因子)

#define _for(i,a,b) for(int i = (a);i < b;i ++)

class Solution
{
    public:
        bool judge(string s1,string s2)
        {
            if(s2.size()%s1.size()!=0)
                return false;
            for(int i = 0;i < s2.size();i ++)
            {
                if(s1[i%s1.size()]!=s2[i])
                    return false;
            }
            return true;
        }
        string gcdOfStrings(string str1, string str2)
        {
            string rnt = "";
            string tmp;
            if(str1.size()<str2.size())
            {
                string t = str1;
                str1 = str2;
                str2 = t;
            }
            for(int i = 0;i < str2.size();i ++)
            {
                tmp += str2[i];
                if(judge(tmp,str1)&&judge(tmp,str2))
                {
                    rnt = tmp;
                }
            } 
            return rnt;
        }
};