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Queue

Goal​

What if we need a List with a very specific access policy?

Mechanics​

Once again a queue is an implementation of a List, but with a FIFO policy. This means that the first element that is added to the queue is the first one to be removed.

Analogy​

A queue can be visualized as a line of people waiting to buy tickets. The first person in line is the first person to be served.

Complexity of Operations​

OperationComplexityDescription
enqueue()O(1)Adds an element to the back of the queue
dequeue()O(1)Removes and returns the element at the front of the queue
peek()O(1)Returns the element at the front of the queue without removing it

Use Cases​

Queues are used in many applications such as:

  • Task scheduling in operating systems.
  • Kafka streams in distributed systems.
  • CI/CD pipelines in software development.