text: #include <ext/hash_set>
  #include <iostream>
  using namespace std;
  
  int main() {
      typedef __gnu_cxx::hash_set<int> TyHash;
      int data[] = {1, 2, 3, 2, 3, 4};
  
      TyHash unique_set(data, data + 6);
  
      cout << "Set items:" << endl;
      for (TyHash::iterator iter = unique_set.begin(); iter != unique_set.end(); iter++)
            cout << *iter << " ";
      cout << endl;
  }
  