foo.cc: In function 'ULL Hash(const Tree&, int)':
foo.cc:38:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < v.size(); ++i)
                  ~~^~~~~~~~~~
foo.cc: In function 'int main()':
foo.cc:68:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int j = 1; j < ans[i].size(); ++j)
                   ~~^~~~~~~~~~~~~~~

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

{"receive":"2020-07-24T14:31:28.015Z","handle":"2020-07-24T14:31:28.015Z","cache_start":"2020-07-24T14:31:28.021Z","read_cases":"2020-07-24T14:31:28.150Z","judge":"2020-07-24T14:31:28.150Z","done":"2020-07-24T14:31:29.077Z"}