foo.cc: In function 'void solve()':
foo.cc:7:6: warning: unused variable 'flag' [-Wunused-variable]
  int flag=0;
      ^~~~
foo.cc:11:9: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    scanf("%d",&a[i*9+j]);
    ~~~~~^~~~~~~~~~~~~~~~
foo.cc: In function 'int main()':
foo.cc:47:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
  ~~~~~^~~~~~~~~

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

{"receive":"2020-07-14T07:09:06.877Z","handle":"2020-07-14T07:09:06.877Z","cache_start":"2020-07-14T07:09:06.885Z","read_cases":"2020-07-14T07:09:07.071Z","judge":"2020-07-14T07:09:07.073Z","done":"2020-07-14T07:09:07.493Z"}