foo.cc: In function 'int main()':
foo.cc:24:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<vec.size();i++){
                 ~^~~~~~~~~~~
foo.cc:25:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int j=i+1;j<vec.size();j++){
                       ~^~~~~~~~~~~

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

{"receive":"2020-07-18T14:41:16.804Z","handle":"2020-07-18T14:41:16.804Z","cache_start":"2020-07-18T14:41:16.813Z","read_cases":"2020-07-18T14:41:17.006Z","judge":"2020-07-18T14:41:17.009Z","done":"2020-07-18T14:41:17.491Z"}