简单粗暴，巧妙利用string的相关函数

#include<cstdio>
#include<iostream>
#include<regex>
using namespace std;
int main(){
    string s1,s2,s3;
    cin >>s1 >>s2;
    if (s1.size()<s2.size()) {
        s3=s2;
        s2=s1;
        s1=s3;
    }
    s1=s1+s1;

    if (s1.find(s2)!=s1.npos) {
        cout << "true" << endl;
    }
    else{
        cout << "false" << endl;
    }


    return 0;
}