foo.cc: In function 'int dfs(int)':
foo.cc:20:8: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if(x > result)
      ~~^~~~~~~~
foo.cc: In function 'int main()':
foo.cc:31:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i = 0; i < t; i++)
                 ~~^~~

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