combo.cpp: In function 'std::string guess_sequence(int)':
combo.cpp:8:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
8 | for(int k=0;k<a.size();k++)
| ~^~~~~~~~~
combo.cpp:9:14: error: could not convert 'a.std::__cxx11::basic_string<char>::operator[](((std::__cxx11::basic_string<char>::size_type)k))' from '__gnu_cxx::__alloc_traits<std::allocator<char>, char>::value_type' {aka 'char'} to 'std::string' {aka 'std::__cxx11::basic_string<char>'}
9 | if(press(a[k])==1){
| ^
| |
| __gnu_cxx::__alloc_traits<std::allocator<char>, char>::value_type {aka char}
combo.cpp:13:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
13 | for(int k=0;k<a.size();k++){
| ~^~~~~~~~~
combo.cpp:20:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
20 | for(int k=0;k<a.size();k++){
| ~^~~~~~~~~