foo.cc: In function 'void dfs(int)':
foo.cc:16:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 0;i < mp[x].size();i++){
                   ~~^~~~~~~~~~~~~~
foo.cc: In function 'int main()':
foo.cc:28:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d%d",&n,&s,&m);
     ~~~~~^~~~~~~~~~~~~~~~~~~
foo.cc:31:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d%d",&x,&y,&z);
         ~~~~~^~~~~~~~~~~~~~~~~~~

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

{"receive":"2020-08-12T08:16:23.359Z","handle":"2020-08-12T08:16:23.359Z","cache_start":"2020-08-12T08:16:23.367Z","read_cases":"2020-08-12T08:16:23.494Z","judge":"2020-08-12T08:16:23.495Z","done":"2020-08-12T08:16:26.278Z"}