Data Structures and Algorithms
with Object-Oriented Design Patterns in Java 
Program 
defines the methods
enqueueHead and dequeueHead.
The latter is trivial to implement--it simply calls the dequeue
method inherited from the QueueAsLinkedList class.
The enqueueHead method takes a single argument--the object to be added to the head of the deque. The method simply calls the LinkedList.prepend method. Since the running time for prepend is O(1), the running time of enqueueHead is also O(1).
Copyright © 1998 by Bruno R. Preiss, P.Eng. All rights reserved.