Front and back

Manage front and rear pointers.

In a queue, front is the next element to be removed, back is the last added. These two ends define FIFO.

Looking at front (peek) lets you see the next element without removing it. This is an O(1) operation.

Queue use cases

Queue is used in BFS, printer queues, task schedulers and message queues.

BFS uses a queue to traverse a graph layer by layer. Each node adds its neighbors to the queue.

Write queue_front(queue). Return the front element without removing. Print 8 with print(queue_front([8, 16, 24])).

Show example solution

def queue_front(queue):
    # Show front
    return queue[0]
print(queue_front([8, 16, 24]))

Front

The next element to remove is the ____.

Show answer

The next element to remove is the front.