CIS3023: Programming Fundamentals for CIS Majors II Summer 2010

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# CIS3023: Programming Fundamentals for CIS Majors II Summer 2010 - PowerPoint PPT Presentation

CIS3023: Programming Fundamentals for CIS Majors II Summer 2010. Linked Lists. “ A list is only as strong as its weakest link .” --Donald Knuth. Course Lecture Slides 23 July 2010. Ganesh Viswanathan. [News] Tropical storm Bonnie hit Biscayne Bay, FL this morning!. Credits: NOAA.

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Presentation Transcript

“A list is only as strong as its weakest link.” --Donald Knuth

Course Lecture Slides

23 July 2010

GaneshViswanathan

Credits: NOAA

Data structure
• A way of structuring, storing and organizing data in computers that facilitates efficient operations on the data.
• Data structures help to devise algorithms for solving complex operations on the data in an efficient manner.
Data structures

And many more!

ArrayList
• To insert (remove) an element in (from) the interior of an ArrayList requires shifting of data and is a linear-time O(n) operation!
• Is a collection of linked nodes (think of a chain!)
• Memory allocation for nodes is non-contiguous
• Sports constant time O(1) insertion and updates
• Unrolled Linked Lists (multiple elements in each node)
• Lists with only head pointer nodes
• With head and tail nodes
• With head, tail and cursor (currently requested) nodes

And many more!

• A set of nodes, each containing some data and a link to the next node.
• Dynamic data-structure.
• A set of nodes, each containing some data and a link to the next node.
• Dynamic data-structure.
• Simple implementation,
• Efficient, constant time O(1) insertion and removal operation.
• Node : self-referencing structure
• Link : reference to a node
• Has dedicatedhead and tail indicators
• Create list
• Add node at index i
• Remove node
• Remove node at tail
• Remove node at index i
• Iterate (traverse)the list
• Find node at index
• Find previous node to the one at index i
• Set node at index ito new node
• Size of list
• Clear list
Create (Node)
• public class Node<T>
• {
• // data held by the node
• public T nodeValue;
• // next node in the list
• public Node<T> next;
• // default constructor with no initial value
• public Node()
• {
• nodeValue = null;
• next = null;
• }...
• }

Empty List

If list is empty (head == null) Set both head and tail to point to new node

Insert new node before current head node

Two-step process

1. Update the next link of a new node, to point to the current head node.

Insert new node after current tail node

Two-step process

1. Update the next link of the current tail node, to point to the new node.

2. Update tail link to point to the new node.

If node at index i represents head or tail node, Refer previous pseudo-code for “add node at head/ tail”

Else

Two-step process

1. Update link of the new node, to point to the "next" node.

2. Update link of the "previous" node, to point to the new node.

Remove node from list with only one node

• Both head and tail point to the (same node) only existing node.
• Remove link to the node from both the head and tail, by setting both to null.
• Dispose off the node (set to null)

• Remove the node pointed to by head.
• Two-step process

2. Dispose removed node.

Remove node from tail

• Remove the node pointed to by tail.
• Three-step process

Remove node from tail

1. Update tail link to point to the node, before the tail. In order to find it, list should be traversed first, beginning from the head.

3. Dispose removed node.

2. Set next link of the new tail to NULL.

Remove node at index i

• If index i is not 0 or n-1, this operation removes the node between two nodes.
• Two-step process

Remove node at index i

1. Update next link of the previous node, to point to the next node, relative to the removed node.

2. Dispose removed node.