import java.util.List;

/**
 * This class contains a number of recursive methods for lists.
 *
 * @author Franck van Breugel
*/
public class MyList
{
    /**
     * Tests if the given list contains the given element.
     *
     * @param element the element.
     * @pre. element != null
     * @param list the list.
     * @pre. list != null
     * @return true if the given list contains the given element,
     *  false otherwise.
     */
    public static <T> boolean contains(T element, List<T> list)
    {
        boolean contains;
	if (list.size() == 0)
	{
	    contains = false;
	}
	else
	{
	    T first = list.remove(0);
	    if (element.equals(first))
	    {
		contains = true;
	    }
	    else
	    {
		contains = MyList.contains(element, list);
	    }
	}
	return contains;
    }

    /**
     * Tests if the given list is constant, that is, if all
     * elements are the same.
     *
     * @param list the list.
     * @pre. list != null and list does not contain null
     * @return true if the given list is constant, false otherwise.
    */
    public static <T> boolean isConstant(List<T> list)
    {
      boolean constant;
      if (list.size() <= 1)
      {
	  constant = true;
      }
      else
      {
	  if (!list.get(0).equals(list.get(1)))
	  {
	      constant = false;
	  }
	  else
	  {
	      list.remove(0);
	      constant = MyList.isConstant(list);
	  }
      }
      return constant;
    }

    /**
     * Returns the minimum element of the given list.
     *
     * @param list the list.
     * @pre. list != null and list.size() > 0 and list does not contain null
     * @return the minimum element of the given list.
    */
    public static int min(List<Integer> list)
    {
      int minimum;
      if (list.size() == 1)
      {
	  minimum = list.get(0);
      }
      else
      {
	  int first = list.remove(0);
	  minimum = Math.min(first, MyList.min(list));
      }
      return minimum;
    }

    /**
     * Tests if the given list consists of the powers of two,
     * that is, it is of the form [], [1, 2], [1, 2, 4] etc.
     *
     * @param list the list.
     * @return true if the given list consists of the powers of two,
     * false otherwise.
    */
    public static boolean isPowersOfTwo(List<Integer> list)
    {
      boolean valid;

      return valid;
    }
}