foo.cc: In function 'std::__cxx11::string dfs(int)':
foo.cc:13:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<e[x].size();i++)
              ~^~~~~~~~~~~~
foo.cc:19:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<st.size();i++)
              ~^~~~~~~~~~

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

{"receive":"2020-07-21T02:52:33.487Z","handle":"2020-07-21T02:52:33.487Z","cache_start":"2020-07-21T02:52:33.493Z","read_cases":"2020-07-21T02:52:33.625Z","judge":"2020-07-21T02:52:33.626Z","done":"2020-07-21T02:52:34.344Z"}