combo.cpp: In function 'void shuffle(std::string&)':
combo.cpp:9:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
9 | for (int i = 1; i < s.size(); i++) swap(s[rand() % (i + 1)], s[i]);
| ~~^~~~~~~~~~
combo.cpp: In function 'std::string guess_sequence(int)':
combo.cpp:29:20: warning: comparison of integer expressions of different signedness: 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
29 | if (ans.size() != ln) ans += s.back();
| ~~~~~~~~~~~^~~~~