1. Doubly Linked Lists or Two-way Linked Lists
12/8/2018
Doubly Linked Lists or Two-way Linked Lists
© 2014 Goodrich, Tamassia, Goldwasser
Doubly Linked Lists

2. Doubly Linked List (or Two-way 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 (don’t forget to deallocate the deleted node)
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. == (equality) struct Person person1, person2;
What is the difference between
person1 == person2
Person3 == person4
© 2014 Goodrich, Tamassia, Goldwasser
Doubly Linked Lists