vector
      
        v1;// remove A *a1for (vector
       
        ::iterator it = v1.begin(); it != v1.end(); ++it) {    if (*it == a1) v1.erase(it);}unordered_map
        
          m;// remove B *b1for (unordered_map
         
          ::iterator it = m.begin(); it != m.end(); ++it) {    if (it->second == b1) m.erase(it);}