1. Chapter 4 Link Based Implementations
CS Data Structures
Mehmet H Gunes
Modified from authors’ slides

2. Figure 4-1 A freight train
Preliminaries
Another way to organize data items
Place them within objects—usually called nodes
Linked together into a “chain,” one after the other
Figure 4-1 A freight train
Data Structures and Problem Solving with C++: Walls and Mirrors, Carrano and Henry, © 2017

3. Preliminaries Components that can be linked A node
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4. Preliminaries Several nodes linked together
Data Structures and Problem Solving with C++: Walls and Mirrors, Carrano and Henry, © 2017

5. Preliminaries A head pointer to the first of several linked nodes
Data Structures and Problem Solving with C++: Walls and Mirrors, Carrano and Henry, © 2017

6. Preliminaries A lost node
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7. The Class Node
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8. The Class Node
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9. The Class Node
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10. Link-Based Implementation of ADT Bag
A link-based implementation of the ADT bag
Bag operations, given in UML notation
Data Structures and Problem Solving with C++: Walls and Mirrors, Carrano and Henry, © 2017

11. The header file for the class LinkedBag
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12. The header file for the class LinkedBag
Data Structures and Problem Solving with C++: Walls and Mirrors, Carrano and Henry, © 2017

13. Defining the Core Methods
Default Constructor
Inserting at the beginning of a linked chain
Data Structures and Problem Solving with C++: Walls and Mirrors, Carrano and Henry, © 2017

14. Link-Based Implementation of ADT Bag
Inserting at the beginning of a linked chain
Data Structures and Problem Solving with C++: Walls and Mirrors, Carrano and Henry, © 2017

15. Defining the Core Methods
Traverse operation visits each node in linked chain
Must move from node to node
High-level pseudocode for this loop
Data Structures and Problem Solving with C++: Walls and Mirrors, Carrano and Henry, © 2017

16. Link-Based Implementation of ADT Bag
The effect of the assignment curPtr = curPtr->getNext()
Data Structures and Problem Solving with C++: Walls and Mirrors, Carrano and Henry, © 2017

17. Defining the Core Methods
Definition of toVector
Data Structures and Problem Solving with C++: Walls and Mirrors, Carrano and Henry, © 2017

18. Defining the Core Methods
Methods isEmpty and getCurrentSize
Data Structures and Problem Solving with C++: Walls and Mirrors, Carrano and Henry, © 2017

19. Implementing More Methods
Method getFrequencyOf
Data Structures and Problem Solving with C++: Walls and Mirrors, Carrano and Henry, © 2017

20. Implementing More Methods
Search for a specific entry.
To avoid duplicate code, we perform this search in a private method
Data Structures and Problem Solving with C++: Walls and Mirrors, Carrano and Henry, © 2017

21. Implementing More Methods
Note: definition of the method contains calls getPointerTo
Data Structures and Problem Solving with C++: Walls and Mirrors, Carrano and Henry, © 2017

22. Implementing More Methods
Method remove also calls getPointerTo
Data Structures and Problem Solving with C++: Walls and Mirrors, Carrano and Henry, © 2017

23. Implementing More Methods
Method clear deallocates all nodes in the chain
Data Structures and Problem Solving with C++: Walls and Mirrors, Carrano and Henry, © 2017

24. Implementing More Methods
Destructor calls clear, destroys instance of a class
Data Structures and Problem Solving with C++: Walls and Mirrors, Carrano and Henry, © 2017

25. Link-Based Implementation of ADT Bag
(a) A linked chain and its shallow copy;
Data Structures and Problem Solving with C++: Walls and Mirrors, Carrano and Henry, © 2017

26. Testing Multiple ADT Implementations
(b) a linked chain and its deep copy
Data Structures and Problem Solving with C++: Walls and Mirrors, Carrano and Henry, © 2017

27. Implementing More Methods
Copy constructor to accomplish deep copy.
Data Structures and Problem Solving with C++: Walls and Mirrors, Carrano and Henry, © 2017

28. Implementing More Methods
Copy constructor to accomplish deep copy.
Data Structures and Problem Solving with C++: Walls and Mirrors, Carrano and Henry, © 2017

29. Testing Multiple ADT implementations
Used ADT bag methods when we tested our implementation
test program of Listing 3-2
Can use the same code—with a few changes
Change each occurrence of ArrayBag to LinkedBag and recompile the program
Data Structures and Problem Solving with C++: Walls and Mirrors, Carrano and Henry, © 2017

30. Testing Multiple ADT Implementations
A program that tests the core methods of classes that are derived from the abstract class BagInterface
Data Structures and Problem Solving with C++: Walls and Mirrors, Carrano and Henry, © 2017

31. Testing Multiple ADT Implementations
A program that tests the core methods of classes that are derived from the abstract class BagInterface
Data Structures and Problem Solving with C++: Walls and Mirrors, Carrano and Henry, © 2017

32. Testing Multiple ADT Implementations
A program that tests the core methods of classes that are derived from the abstract class BagInterface
Data Structures and Problem Solving with C++: Walls and Mirrors, Carrano and Henry, © 2017

33. Testing Multiple ADT Implementations
A program that tests the core methods of classes that are derived from the abstract class BagInterface
Data Structures and Problem Solving with C++: Walls and Mirrors, Carrano and Henry, © 2017

34. Testing Multiple ADT Implementations
Sample output 1 of test program
Data Structures and Problem Solving with C++: Walls and Mirrors, Carrano and Henry, © 2017

35. Testing Multiple ADT Implementations
Sample output 2 of test program
Data Structures and Problem Solving with C++: Walls and Mirrors, Carrano and Henry, © 2017

36. Comparing Array-Based and Link-Based Implementations
Arrays easy to use, but have fixed size
Not always easy to predict number of items in ADT
Array could waste space
Can be dynamically resized
Increasing size of dynamically allocated array can waste storage and time
Can access array items directly with equal access time
Dynamic arrays are better when direct access of items is frequent
Data Structures and Problem Solving with C++: Walls and Mirrors, Carrano and Henry, © 2017

37. Comparing Array-Based and Link-Based Implementations
Linked chains do not have fixed size
In a chain of linked nodes, an item points explicitly to the next item
Link-based implementation requires more memory
Array items accessed directly, equal access time
Must traverse linked chain for ith item
access time varies
Data Structures and Problem Solving with C++: Walls and Mirrors, Carrano and Henry, © 2017

38. What is a Circular Linked List?
A circular linked list is a list in which every node has a successor; the “last” element is succeeded by the “first” element.

39. External Pointer to the Last Node

40. What is a Doubly Linked List?
A doubly linked list is a list in which each node is linked to both its successor and its predecessor.

41. Insert Item algorithm for Sorted Linked List
Find proper position for the new element in the sorted list using two pointers predLoc and location, where predLoc trails behind location.
Obtain a node for insertion and place item in it.
Insert the node by adjusting pointers.
Increment length. 49

42. The Inchworm Effect 50

43. Linking the New Node into the List

44. Deleting from a Doubly Linked List
What are the advantages of a circular doubly linked list?

45. A linked list in static storage ?
A Linked List as an Array of Records

46. A Sorted list Stored in an Array of Nodes

47. An Array with Linked List of Values and Free Space

48. An Array with Three Lists (Including the Free List)