public class LinkedSimpleCollection<E> implements SimpleCollection<E> {
  Node<E> first = null;

  public boolean add(E element) {
    Node<E> newnode = new Node<E>(element, first);
    first = newnode;
    return true;
  }

  public boolean contains(Object o) {
    for (Node<E> current = first; current != null; current = current.next) {
      if ( (current.element == null && o == null)
          || current.element.equals(o)) {
        return true;
      }
    }
    return false;
  }

  public SimpleIterator<E> iterator() {
    return new LinkedSimpleIterator<E>(this);
  }

  public void rotate(){
    if (first == null || first.next == null)
      return;
    Node<E> f = first;
    first = first.next;
    Node<E> curr = first;
    while (curr.next != null) 
      curr = curr.next;
    curr.next = f;
    f.next = null; 
  }

  public void reverse(){
    Node<E> current = first;
    first = null;
    while (current != null) {
        Node<E> save = current;
        current = current.next;
        save.next = first;
        first = save;
    }
  }

  public void removeAll(E toRemove){
    while(first != null && first.element.equals(toRemove))
      first = first.next;
    
    if(first == null)
      return;
    
    Node<E> current = first.next;
    Node<E> previous = first;
    
    while(current != null){
      if (current.element.equals(toRemove)) {
        if (previous == null) 
            throw new IllegalStateException(); 
        else 
            previous.next = current.next;
      } else {
          previous = current;
      }
      
      current = current.next;
    }
  }
}