DATA STRUCTURES

Data Structures

• A way of organizing data so that it can be used efficiently.

• Choice of data structure determines how efficiently the program runs.

• Choosing a data structure depends on data operations and frequency.

• Each data structure requires space for storage, time for operations

Data Structure Examples - Stack

Data Structure Examples - Queue

Data Structure Examples – Linked Lists

NULLDATANEXTDATANEXTDATANEXTDATA

Linked List and Nodes

NULLDATANEXTDATANEXTDATANEXTDATA

NEXTDATA

A Node Object{Variable to hold data;Variable to hold next reference;}

VALUE REFERENCE

Adding to a list

NULLDATANEXTDATANEXTDATANEXTDATA

Last In First Out

NULLDATANEXTDATANEXTDATANEXTDATA

First In Last Out

ADDED FIRST

ADDED LAST

ADDED FIRST

ADDED LAST

Adding the first node

NULLDATA

1. Create an object of type Node which contains value for data and whose next reference value is null

NULLDATA

FIRST

2. Store the reference to this newly created object in a variable.

Adding subsequent nodes

NULLDATA

1. Create an object of type Node which contains value for data and whose next reference value is null

NEXTDATA

FIRST

2. Append this new node before or after the current node. Update the NEXT and FIRST references.

NULLDATA

Inserting node

NEXTDATA NEXTDATA

FIRST

NULLDATA

NULLDATA NEXT

Removing first node

NEXTDATA

FIRST

NEXTDATA NULLDATA

FIRST

Removing specific node

NEXTDATA NULLDATA

CURRENT

NEXTDATANEXTDATA

PREVIOUS

CURRENT CURRENT

PREVIOUS

Match? Match?FOUND!!Match?

What we talked about

• Data structures and why we need them

• How linked lists work

• Adding and removing from a linked list