foo.cc: In function 'void dfs(int, int)':
foo.cc:10:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i=0; i<t[x].size(); i++)
                ~^~~~~~~~~~~~
foo.cc: In function 'int hsh(int)':
foo.cc:21:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i=0; i<t[x].size(); i++)
                ~^~~~~~~~~~~~
foo.cc:28:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i=0; i<h.size(); i++) ansx = (ansx + (h[i]+1)*(i+1))%100000007;
                ~^~~~~~~~~
foo.cc: In function 'int main()':
foo.cc:52:6: warning: unused variable 'num' [-Wunused-variable]
  int num = 1;
      ^~~

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

{"receive":"2020-07-21T12:33:14.460Z","handle":"2020-07-21T12:33:14.460Z","cache_start":"2020-07-21T12:33:14.467Z","read_cases":"2020-07-21T12:33:14.593Z","judge":"2020-07-21T12:33:14.594Z","done":"2020-07-21T12:33:15.869Z"}