Data Structures & Algorithms Lec. 6: Queues

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Questions and Answers

What is the primary characteristic of a queue data structure?

Elements are added from the front and removed from the rear

Elements are added and removed from the same end

First in, first out (correct)

Last in, first out

In a queue, which operation is typically performed at the rear?

Check if queue is full

Initialize

Dequeue

Enqueue (correct)

What is the purpose of a queue in communication software?

To prioritize tasks

To hold information received over networks and dial-up connections (correct)

To allocate memory efficiently

To manage multiple user requests

What is the advantage of implementing a queue as a linked list?

It can expand or shrink with each enqueue or dequeue operation Signup and view all the answers

In a queue, which operation is performed when the queue is not full?

Enqueue Signup and view all the answers

What is the role of a queue in an operating system?

To handle multiple user requests simultaneously Signup and view all the answers

What is the primary drawback of implementing a linear queue?

It is expensive to use for a long queue Signup and view all the answers

What is the main purpose of the mod operator in circular queue representation?

To accomplish the 'wrap-around' effect Signup and view all the answers

In a linear queue implementation, where does the addition of an item to the queue occur?

One past the last currently occupied slot Signup and view all the answers

What operation does not remove an item from the queue?

Peek Signup and view all the answers

In a circular queue representation, where does the front of the queue point to?

The first occupied cell Signup and view all the answers

What is the first step in the EnQueue operation?

Check if the queue is full Signup and view all the answers

What is the purpose of the 'isFull' function in the Queue class?

To determine if the queue is full and produce an overflow error Signup and view all the answers

What happens when the 'front' pointer is incremented during the DeQueue operation?

The 'front' pointer points to the next accessible data Signup and view all the answers

What is the purpose of the 'isEmpty' function in the Queue class?

To check if the queue is empty Signup and view all the answers

What happens when the 'rear' pointer is incremented during the EnQueue operation?

An element is added to the queue Signup and view all the answers

What is the maximum size of the queue defined in the code?

5 Signup and view all the answers

Study Notes

Queue Data Structure

A queue is a collection of homogeneous elements, in which new elements are added from one end (the rear or back), and elements are removed from the other end (the front).
A queue is a FIFO (First-In-First-Out) structure.

Queue Operations

Enqueue: adds an item to the queue at the rear end.
Dequeue: removes an item from the queue from the front end.
Peek: gets an element at the front of the queue without removing it.

Queue Implementation

Linear Queue: implemented using an array, with a fixed size.
Circular Queue: implemented using a circular array, allowing the queue to "wrap-around" when it reaches the end of the array.

Circular Queue Representation

The "wrap-around" is accomplished using the modulo operator (%).
Rear = (rear + 1) % maxQue, front = (front + 1) % maxQue.

Enqueue Operation

Check if the queue is full.
If full, produce an overflow error and exit.
Else, increment the 'rear' and add an element to the location pointed by 'rear'.
Return success.

Dequeue Operation

Check if the queue is empty.
If empty, display an underflow error and exit.
Else, access the element pointed by 'front'.
Increment the 'front' to point to the next accessible data.
Return success.

Queue in Real Life

Applications: operating system multi-user/multitasking environments, communication software, air traffic control systems, and other applications where multiple tasks or requests need to be processed in a sequential order.

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Description

This quiz covers the concept of queues in data structures and algorithms, including the logical model and differences with stacks. Test your understanding of queue operations and properties.