foo.cc: In function 'void dfs(int)':
foo.cc:30:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 0;i < mp[x].size();i++){
                   ~~^~~~~~~~~~~~~~

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

{"receive":"2020-08-12T08:39:18.955Z","handle":"2020-08-12T08:39:18.955Z","cache_start":"2020-08-12T08:39:18.964Z","read_cases":"2020-08-12T08:39:19.094Z","judge":"2020-08-12T08:39:19.095Z","done":"2020-08-12T08:39:21.646Z"}