queue - QUEUES A queue is a list from which items may be...

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1 QUEUES A queue is a list from which items may be deleted at one end (front) and into which items may be inserted at the other end (rear) Similar to checkout line in a grocery store - first come first served. It is referred to as a first-in-first-out (FIFO) data structure. Queues have many applications in computer systems: - jobs in a single processor computer - print spooling - information packets in computer networks. Primitive operations enqueue (q, x): inserts item x at the rear of the queue q x = dequeue (q): removes the front element from q and returns its value. isEmpty(q) : true if the queue is empty, otherwise false. front rear 2 Example enqueue(q, ‘A’); enqueue(q, ‘B’); enqueue(q, ‘C’); x = dequeue(q); enqueue(q, ‘D’); enqueue(q, ‘E’); x= dequeue (q) -> x= ‘A’ front rear A B C front rear B C D E
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3 Linked List Implementation We need to keep two pointers: front and rear struct queueNode{ char data; struct queueNode * next; }; struct queue{ struct queueNode *front;
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queue - QUEUES A queue is a list from which items may be...

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