foo.cc: In function 'int main()':
foo.cc:10:18: warning: format '%lf' expects argument of type 'double', but argument 2 has type 'int' [-Wformat=]
  printf("%.2lf",c);
                  ^

自豪的采用jd5进行评测(github.com/masnn/jd5)

{"receive":"2020-02-16T08:39:21.323Z","handle":"2020-02-16T08:39:21.323Z","cache_start":"2020-02-16T08:39:21.324Z","read_cases":"2020-02-16T08:39:21.693Z","judge":"2020-02-16T08:39:21.694Z","done":"2020-02-16T08:39:22.210Z"}