1. G64ADS Advanced Data Structures
Guoping Qiu
Room C34, CS Building

2. Abstract Data Type (ADT)
In Object Oriented Programming data and the operations that manipulate that data are grouped together in classes
Abstract Data Types (ADTs) or data structures or collections store data and allow various operations on the data to access and change it

3. Why Abstraction
Specify the operations of the data structure and leave implementation details to later
Java uses an interface to specify operations
Many, many different ADTs
Picking the right one for the job is an important step in design
High level languages often provide built in ADTs,
The C++ STL, the Java standard library

4. The List ADT List of size N: A0, A1, …, AN-1
Each element Ak has a unique position in the list
Elements can be arbitrarily complex
Operations
insert(X, k), remove(k), find(X), findKth(k), printList()

5. Lists Using Arrays Operations insert(X,k) – O(N) remove(k) – O(N)
find(X) – O(N)
findKth(k) – O(1)
printList() – O(N)

6. Linked Lists Elements not stored in contiguous memory
Nodes in list consist of data element and next pointer

7. Linked Lists
Operation – insertion
Insert (X, A) – O(1)

8. Linked Lists
Operation – deletion
delete (A) – O(1)

9. Linked Lists Operations find(X) – O(N) findKth(k) – O(N)
printList() – O(N)

10. Linked Lists
Doubly-linked list

11. List Implementation
In Java

12. List Implementation Example: Using remove on a linkedlist
Quadratic time on all list

13. List Implementation Example: Using remove on a linkedlist
Quadratic time on arraylist, linear time on linkedlist

14. Stack
Stack is a list where insert and remove take place only at the “top”
Operations
Push (insert) element on top of stack
Pop (remove) element from top of stack
Top: return element at top of stack
LIFO (Last In First Out)

15. Stack Implementation Stack is a list, any list implementation will do
Linked list implementation
Array implementation

16. Stack Applications
Balancing Symbols

17. Stack Applications
Balancing Symbols

18. Stack Applications
Postfix Expressions

19. Stack Applications
Infix to Postfix Conversion

20. Stack Applications
Method Calls

21. Queue
Queue is a list where insert takes place at back, but remove takes place at the front
Operations
Enqueue (insert) element at the back of the queue
Dequeue (remove and return) element from the front of the queue
FIFO (First In First Out)

22. Queue

23. Queue Implementation
Array implementation of Queue

24. Queue Application Job Scheduling Priority queues Graph traversals
Queuing theory