Data Structures

Lecturer slide on Data Structures

Transcript

1. Data Structures Dasar-dasar Pemrograman
2. Agenda • Data Structures • Linked List • Abstract Data Types • Stack • Queue
3. Data Structures
4. Data Structures • Static Data Structures • Array • Fixed Length • Fast speed for read-write operation • Not flexible enough
5. Data Structures • Dynamic Data Structures • Linear: Linked List, Stack, Queue, etc. • Binary Trees • Size can grow easily • Dynamic Memory Allocation • Slow in read-write operations
6. Linked List and its implementation
7. Linked List • Linear collection of “Node” • Node • Can contain data of any type • Contain reference to next Node
8. Linked List • A linked list object usually contains only reference to first object • Accessing each subsequent node via the link reference stored in previous node
9. Linked List • Fast in adding and removing elements • Visiting in a sequential order is efficient • Random Access is inefficient
10. Linked List • Single Linked List • Each node contains one reference to the next node in the list • Double Linked List • Each node contains reference to next and previous node in the list
11. Linked List
12. Linked List • Java implementation located in java.util.LinkedList • Generic class • Can not contain primitive • Must used Wrapper class
13. Linked List
14. Linked List • Accessing Node inside a linked list • Encapsulate a position inside a linked list • Protects the linked list whilst giving acccess • Solution in Java: ListIterator interface
15. ListIterator
16. ListIterator
17. ListIterator • Initially, iterator points before first element • iterator: like a cursor between 2 letters • Move the iterator: next() method • Throws NoSuchElementException if pass the end of the list
18. ListIterator • Checking for next element in a list: hasNext() method • Other methods available: • previous() • hasPrevious()
19. ListIterator
20. ListIterator • Supported operations: • Adding new element • Removing element from Linked List
21. ListIterator • Removing element • Remove element from Linked List • Returns the object
22. ListIterator • Removing element • Can call remove() once after next() or previous() • Can not remove() after add() • Throws IllegalStateException
23. ListIterator • Adding new element • Using add() method • Add an object after iterator position • Moves iterator pass new object
24. ListIterator
25. Linked List • Implementing our own LinkedList • Simplified version • Singly Linked List • Use Object, not Type parameter • Only provide access to first element
26. Linked List • Node • Store data as Object • Link (reference) to next Node • Make Node as private inner class for LinkedList
27. Linked List • Linked List • Hold reference to first Node • Has methods: • getFirst() • addFirst() • removeFirst()
28. Linked List • Adding new Node to the list • New Node becomes head of the list • The old ‘head’ becomes its next Node
29. Linked List
30. Linked List • Remove first Node • Save data for later being returned • The successor becomes the first Node
31. Linked List
32. Linked List • Implements ListIterator interface as inner class • LinkedListIterator • Has access to Node class and first Node
33. Linked List Iterator • Implementing next() method • Store last visited node as position • Store before last position as previous • next() called, position is advanced to position.next • The old position stored in previous
34. LinkedListIterator • Implementing remove() method • If the element is the head of list, call removeFirst() method • Otherwise, update the reference in preceding Node to skip the removed element • It is illegal to call remove() twice in a row
35. LinkedListIterator
36. LinkedListIterator • Implement set() method • Change data stored in previous visited element
37. LinkedListIterator • Implement add() method • The most complex operation • Inserting new Node after current position • Update next Node reference in current position and new Node
38. LinkedListIterator
39. Demo
40. Abstract Data Types
41. Abstract Data Types • Define the fundamental operation • Do not specify the implementation • Example • Linked List and Array List • List • Array
42. Stack
43. Stack • Last In, First Out • Allows insertion and removal at one end • Top of the stack • Using push() and pop() • Stack of Books
44. Stack
45. Stack • Stack usually used by: • Virtual machine to trace program execution • Compiler to evaluate arithmetic expression
46. Queue
47. Queue • First In, First Out • Adding items to the end of the queue • Tail of a Queue • Removing items from the start of the queue • Head of a Queue
48. Queue • Items are removed in the same order which they have been added • People lining up
49. Queue
50. Queue • Example: • Queue of Print Spool • GUI Events
51. Stack and Queue
52. Questions?