void pAOSOAutostepGradTree::get_is_leaf( VecInt& is_leaf )
{
  is_leaf.clear();
  is_leaf.resize(nodes_.size());

  std::list<pAOSOAutostepGradNode>::iterator it = nodes_.begin();
  for (int i = 0; it!=nodes_.end(); ++it, ++i) {
    if (it->left_==0 && it->right_==0)
      is_leaf[i] = 1;
    else
      is_leaf[i] = 0;
  } // for i
}