unique example

 int  main()  {
     int  a[ ]  =  {1,1,2,1,2,3,1,1,1,2,3,2,2};
     const  int  N  =  13;
     int  *i  =  unique(a,  a + N);
     copy(a,  i,
                 ostream_iterator<int>(cout, "  "));
     cout  <<  endl;
     copy(i,  a + N,
                 ostream_iterator<int>(cout, "  "));
     cout  <<  endl;
 }