foo.cc: In function 'int main()':
foo.cc:47:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<s.size();i++)
              ~^~~~~~~~~
foo.cc:49:13: warning: array subscript has type 'char' [-Wchar-subscripts]
   if(bd[s[i]])
             ^
foo.cc:51:17: warning: array subscript has type 'char' [-Wchar-subscripts]
    if(!bd[s[i-1]])hz+='.';
                 ^
foo.cc:52:14: warning: array subscript has type 'char' [-Wchar-subscripts]
    if(bd[s[i]]==1)
              ^
foo.cc:56:19: warning: array subscript has type 'char' [-Wchar-subscripts]
    else if(bd[s[i]]==5)
                   ^
foo.cc:70:39: warning: array subscript has type 'char' [-Wchar-subscripts]
      while(!st2.empty()&&(bd[st2.top()]>=bd[s[i]]))
                                       ^
foo.cc:70:49: warning: array subscript has type 'char' [-Wchar-subscripts]
      while(!st2.empty()&&(bd[st2.top()]>=bd[s[i]]))
                                                 ^
foo.cc:84:22: warning: array subscript has type 'char' [-Wchar-subscripts]
  if(!bd[s[s.size()-1]])hz+='.';
                      ^
foo.cc:91:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<hz.size();i++)
              ~^~~~~~~~~~

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