foo.cc: In function 'void TreeDP(int, int)':
foo.cc:42:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int z = 0; z < edge[x].size(); z++)
                  ~~^~~~~~~~~~~~~~~~
foo.cc:48:17: warning: unused variable 'tmp2' [-Wunused-variable]
    ll tmp1 = 0, tmp2 = 0;
                 ^~~~
foo.cc:70:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int z = 0; z < edge[x].size(); z++) if (edge[x][z] != st) num[++len] = edge[x][z];
                  ~~^~~~~~~~~~~~~~~~

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