word breaking --- DP

Given a dictionary and a URL, break URL into several keywords, if possible.
e.g., bedbathandbeyond into bed bath and beyond, also bed bat hand beyond

Classical DP:
actually very simple DP, only need to check if T[j] is one, then S[j+1...i] is a word or not

Code:
vector word_breaking(const string &s, const unordered_set &dict)
{
   vector T(s.size(), 0);
   for (int i=0; i   {
       // set T[i] if s(0,i) is a valid word
       if (dict.find(s.substr(0, i+1)) != dict.cend() ) T[i] = i+1;
     // set T[i] if T[j]!=0 and s(j+1, i) is a valid word
       for (int j=0; j          if (T[j]!=0 && dict.find( s.substr(j+1, i-j))!=dict.cend() )
               T[i] = i-j;
   }

   vector ret;
   if ( T.back() )
   {
       int idx = s.size() - 1;
       while(idx >=0)
       {
           ret.emplace_back(s.substr(idx - T[idx] +1 , T[idx]) );
           idx  -= T[idx];
       }
       reverse(ret.begin(), ret.end());
   }
return ret;
}