# Exercise 10.2.3

Implement a queue by using a singly linked list L. The operations ENQUEUE and DEQUEUE should still take $\O(1)$ time.

This is also too simple to be worth implementing.

The ENQUEUE operation inserts an element in the beginning of the list and the DEQUEUE operation removes an element from the end of the list. In this case we need to keep track of the last element of the list. We can do that with a sentinel.