Queues

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Contents

• Operations on a Queue
• Linear Queue
• Circular Queue
• Priority Queues

What are queues

A queue is a first in first out data structure. Any new items can only be added the end of the queue. Items may only be removed from the front of the queue.

Usages

• Printers
• CPU interrupts
• Keys pressed on a keyboard.

Operations on a Queue

Operations on a Queue

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Queues have operations on them that allow for items to be removed and added from the queue.

Basic operations

Here is a basic queue with its pointers

←A	B	C	D	←
front=0			rear=3

Adding (enqueue)

←A	B	C	D	E	←
front=0				rear=4

Removing (dequeue)

Note

The elements do not move.

	B	C	D	E	←
	front=1			rear=4

Other operations

• isEmpty - Checks if the array is empty or not
• isFull - Checks if the array is full or not

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