foo.cc: In function 'bool cmp(std::__cxx11::string, std::__cxx11::string)':
foo.cc:10:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < a.size(); i ++ )
                  ~~^~~~~~~~~~
foo.cc: In function 'std::vector<int> sup(std::vector<int>&, std::vector<int>&)':
foo.cc:20:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < a.size(); i ++ )
                  ~~^~~~~~~~~~
foo.cc:24:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if (i < b.size())
       ~~^~~~~~~~~~

自豪的采用 HydroJudge 进行评测(github.com/hydro-dev/HydroJudge)

{"receive":"2020-08-17T02:55:40.657Z","handle":"2020-08-17T02:55:40.657Z","cache_start":"2020-08-17T02:55:40.664Z","read_cases":"2020-08-17T02:55:40.859Z","judge":"2020-08-17T02:55:40.862Z","done":"2020-08-17T02:55:41.336Z"}