Author: Stan Eisenstat
Subject: Re: [Cs223] remD
Date: Wednesday, 25 Mar 2020, 17:19:16

    > Message Posted By: Unknown
    >
    > Hi, for remD,
    >
    > do we need to move the last element in the Tail linked list to the end of
    > the Head linked list each time when we call remD?
    >
    > Or do we only need to do that when the Head linked list is empty?

As stated in the specification:

   To remove an item from the head of the Deque, pop it
   off the top of the H stack (but if the H stack is
   empty, first move items one at a time from the top of
   the T stack to the top of the H stack until the T
   stack is empty).

Thus means that when (and only when) the H stack is
empty but the T stack is not, both remD() and headD()
should start by repeatedly moving the top of the T stack
to the top of the H stack until the T stack is empty.

They should never move the last element of the T stack
unless it is the only one.

--Stan-