Variations of Linked Lists CS 302 – Data Structures Sections 6.2, 6.3 and 6.4

Circular Linked Lists Extending a linear linked list to a circular linked list –Make the last node point back to the first node

–To have access to both the first and last nodes of the list, make listData point to the last node Circular Linked Lists (cont’d)

Doubly-Linked Lists: Node structure info: the user's data next, back: the address of the next and previous node in the list.back.next.info

Node structure (cont’d) template struct NodeType { ItemType info; NodeType * next; NodeType * back; };

Inserting an item We no longer need to use prevLocation (we can get the predecessor of a node using its back member). prevLocation location

Inserting into a Doubly Linked List 1. newNode->back = location->back; 3. location->back->next=newNode; 2. newNode->next = location 4. location->back = newNode;

Headers and Trailers Special cases arise when we are dealing with the first or last nodes. Idea: make sure that we never insert or delete the ends of the list! How? Set up dummy nodes with values outside the range of possible values.

Headers and Trailers (cont.) Header Node: contains a value smaller than any possible list element. Trailer Node: contains a value larger than any possible list element.

Implement a linked list using arrays struct NodeType { ItemType info; NodeType* next; }; David Joshua Leah Miriam Robert

A linked list as an array of records: struct NodeType { ItemType info; int next; }; David Joshua Leah Miriam Robert

A linked list as an array of records: How would you Insert/Delete items? David Joshua Leah Miriam Robert Can you implement Binary Search efficiently?

Why would one implement a linked list using arrays? Integer indices take up less memory than pointers. Store/Read lists to/from files more efficiently.

Case Study: Implementing a large integer ADT The range of integer values varies from one computer to another. For long integers, the range is typically [-2,147,483,648 to 2,147,483,647] How can we manipulate larger integers?

Case Study: Implementing a large integer ADT (cont.)