1. Doubly Linked Lists
6/3/2018
Presentation for use with the textbook Data Structures and Algorithms in Java, 6th edition, by M. T. Goodrich, R. Tamassia, and M. H. Goldwasser, Wiley, 2014
Doubly Linked Lists
© 2014 Goodrich, Tamassia, Goldwasser
Doubly Linked Lists

2. Doubly Linked List
A doubly linked list can be traversed forward and backward
Nodes store:
element
link to the previous node
link to the next node
Special trailer and header nodes
prev
next
element
node
trailer
header
nodes/positions
elements
© 2014 Goodrich, Tamassia, Goldwasser
Doubly Linked Lists

3. Header and trailer Make implementation easier
Every insertion/deletion is between two nodes
Can be implemented without them
Save space
Need to consider special cases at the beginning and at the end
© 2014 Goodrich, Tamassia, Goldwasser
Doubly Linked Lists

4. Insertion p A B C p q A B C What are the instructions? X p q A B X C
Insert a new node, q, between p and its successor. p A B C p q A B C
What are the instructions? X p q A B X C
© 2014 Goodrich, Tamassia, Goldwasser
Doubly Linked Lists

5. Deletion A B C D p A B C p What are the instructions? D A B C
Remove a node, p, from a doubly linked list. A B C D p A B C p
What are the instructions? D A B C
© 2014 Goodrich, Tamassia, Goldwasser
Doubly Linked Lists

6. Doubly-Linked List in Java
© 2014 Goodrich, Tamassia, Goldwasser
Doubly Linked Lists

7. Doubly-Linked List in Java, 2
Lines 26-27:
Why are the parameters
different?
Why do we need line 28?
© 2014 Goodrich, Tamassia, Goldwasser
Doubly Linked Lists

8. Doubly-Linked List in Java, 3
© 2014 Goodrich, Tamassia, Goldwasser
Doubly Linked Lists

9. Doubly-Linked List in Java, 4
Do we want to put lines 69 and 70
before line 68?
Why?
© 2014 Goodrich, Tamassia, Goldwasser
Doubly Linked Lists

10. Doubly-Linked List in Java, 4
© 2014 Goodrich, Tamassia, Goldwasser
Doubly Linked Lists

11. == vs equals() Person person1, person2 What is the difference between
person1.equals(person2)
© 2014 Goodrich, Tamassia, Goldwasser
Doubly Linked Lists