Worksheet 10: Linked list Queue Name:
Worksheet 10: Linked List Queue, pointer to Tail
One problem with the linked list stack is that it only permits rapid access to the
front of the collection. This was no problem for the stack operations described in
the last lesson, but would present a difficulty if we tried to implement a queue,
where elements were inserted at one end and removed from the other.
A solution to this problem is to maintain two references into the collection of links.
As before, the data field firstLink refers to the first link in the sequence. But now a
second data field named lastLink will refer to the final link in the sequence:
(To reduce the size of the image the fields in the links have been omitted,
replaced with the graphic arrow). Both the firstLink and lastLink fields can be null
if a list is empty. Removing a data field from the front is the same as before, with
the additional requirement that when the last value is removed and the list
becomes empty the variable lastLink must also be set to null.
Because we have a link to the back, it is easy to add a new value to the end of
the list.
An Active Learning Approach to Data Structures using C 1
