# 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 a bit trickier than the previous one, but still simple.

• We need to keep track of the last element of the list.
• Whenever we ENQUEUE, we should be inserting the element after it and marking the new last element of the list.
• Whenever we DEQUEUE, we should pop the first element of the list.