1. CISC220 Fall 2009 James Atlas Lecture 11: Queues

2. Objectives for Today Queues Deques Array based implementation Reading - K+W Chap 6

3. Queue

4. Queue using an Array (Vector) Linked lists require extra storage of pointers for next front() = get(0) dequeue() = remove(0) queue(x) = insert(x, length) Time complexity? How can we reduce this?

5. Circular Array

6. Implementing Queue With Circular Array

7. Implementing Queue With Circular Array (2)

8. Implementing Queue With Circular Array (3)

9. Reallocating a Circular Array

10. Deque

11. Deque ADT back() front() pushBack(x) pushFront(x) popBack() popFront()

12. Doubly-linked list

13. Inserting into a Double-Linked List DNode* sharon = new DNode("Sharon"); // Link new DNode to its neighbors sharon->next = sam; // Step 1 sharon->prev = sam->prev; // Step 2

14. Inserting into a Double-Linked List (2) // Link old predicessor of sam to new predicessor. sam->prev->next = sharon; // Step 3 // Link to new predicessor. sam->prev = sharon; // Step 4

15. Removal from a Double-Linked List harry->prev->next = harry->next; // Step 1 harry->next->prev = harry->prev; // Step 2 delete harry;

17. Priority Queue ADT front() - returns the highest priority element of the queue without removing it dequeue() - removes (and returns) the highest priority element of the queue queue(x, int) - queues x at the given priority in the queue FIFO structure??

18. Brainstorm Come up with several ways to use our LinkedList to implement a Priority Queue Record the order of operations for each ADT function –front() –dequeue() –queue(x, int)

19. Trees Nonlinear data structure