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Data Structures - Queues. Introducing the Queue. FIFO ~ First In First Out How does a queue (line) work? First person gets in line Second person gets in line after first person etc. The first person to get out of the line is the first person in line
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Introducing the Queue • FIFO ~ First In First Out • How does a queue (line) work? • First person gets in line • Second person gets in line after first person • etc. • The first person to get out of the line is the first person in line • enqueue – data is added to the end (tail) of the queue • dequeue – data is removed from the beginning (head) of the queue • isEmpty – returns True if queue is empty
Queue Example ENQUEUE D ENQUEUE E ENQUEUE A #What is at the head of the line? and the tail? DEQUEUE DEQUEUE #What is at the head of the line? and the tail?
Why do we use queues? • Used to ensure the first-come-first-serve concept • The first things added are the first things to be removed • Where do we see queues in real life? • Where do you think we see queues in technology?
Queue Implementation • How do we implement a queue? • class • Static size vs. Dynamic size • Let’s draw a queue... • Try out some queue operations (enqueue, dequeue, etc.) • What pieces of information do we need to track?
