Page 176 - DCAP201_FUNDAMENTALS_OF_DATA_STRUCTURES

Unit 10: Queues

if (front->next==NULL) Notes
{
free(front);
queueptr = front = rear = NULL;
}
else
{
front=front->next;
free(queueptr);
queueptr = front;
}
}
}

Self Assessment

Fill in the blanks:
6. In a ..................... queue, front will point to one position less to the first element anti-clock
wise.
7. ..................... representation of a circular queue is more efficient as it uses space more
efficiently, of course with the extra cost of storing the pointers.
10.4 Priority Queue

A priority queue is a collection of elements where each element is assigned a priority and the
order in which elements are deleted and processed is determined from the following rules:
An element of higher priority is processed before any element of lower priority.
Two elements with the same priority are processed according to the order in which they are
added to the queue.

Example: An example of a priority queue can be time sharing system: programs of high
priority are processed first, and programs with the same priority form a standard queue.

10.4.1 Array Implementation of Priority Queue

One way to represent priority queue is through arrays.
If an array is used to store the elements of priority queue then insertion is easy but deletion of
elements would be difficult. This is because while inserting elements in the priority queue they
are not inserted in an order. As a result, deleting an element with the highest priority would
require examining the entire array to search for such an element.

Did u know? An element in a queue can be deleted from the front end only.

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