version 1 手动实现全部

#include <iostream>

using namespace std;

int main()
{
    string s1, s2, tp;
    cin >> s1 >> s2;

    if(s1.size()<s2.size())
    {
        tp = s1;
        s1 = s2;
        s2 = tp;
    }

    int q, i, j, k, t;
    for(q = 0; q < s1.size(); q ++)
    {
        auto c = s1.back();
        for(i = s1.size()-1; i >= 0; i --) s1[i] = s1[i - 1];
        s1[0] = c;
        for(j=0; j<s1.size(); j++)
        {
            k = j;
            t = 0;
            while(s1[k] == s2[t] && t < s2.size())
            {
                k ++;
                t ++;
            }
            if(t == s2.size())
            {
                cout << "true";
                return 0;
            }
        }
    }
    cout << "false";
    return 0;
}

version 2 优化循环过程，优化比较过程

#include <iostream>

using namespace std;

int main()
{
    string s1, s2, tp;
    cin >> s1 >> s2;

    if(s1.size()<s2.size())
    {
        tp = s1;
        s1 = s2;
        s2 = tp;
    }

    for(int i = 0; i < s1.size(); i++)
    {
        s1 = s1.substr(1) + s1[0];

        for(int j = 0; j + s2.size() <= s1.size(); j ++)
        {
            int k;
            for(k = 0; k < s2.size(); k ++)
                if(s1[j + k] != s2[k]) 
                    break;

            if(k == s2.size())
            {
                puts("true");
                return 0;
            }
        }
    }

    puts("false");
    return 0;
}