Homework: Stack and Sequence Flip

  1. Implement the Stack family instance method flip declared as follows (this is a Stack<T>): 

        /**
     * Reverses ("flips") {@code this}.
     * 
     * @updates this
     * @ensures this = rev(#this)
     */
    public void flip();

  2. Implement the Sequence family instance method flip declared as follows (this is a Sequence<T>): 

        /**
     * Reverses ("flips") {@code this}.
     * 
     * @updates this
     * @ensures this = rev(#this)
     */
    public void flip();

  3. Provide a second, different implementation of the instance method flip for Sequence<T>. If your first implementation is iterative (i.e., uses a loop), your second one should be recursive and vice versa.