How would you implement a queue using a linked list?

A queue can be implemented using a linked list by adding elements at the end and removing them from the beginning.

In more detail, a queue is a data structure that follows the First-In-First-Out (FIFO) principle. This means that the first element that is added to the queue is the first one to be removed. A linked list, on the other hand, is a linear data structure where each element is a separate object, each containing a reference (link) to the next object in the sequence.

To implement a queue using a linked list, we need to maintain two pointers, one to the head of the list and one to the tail. The head pointer points to the first element in the queue, while the tail pointer points to the last element. When a new element is added (enqueued), it is added at the end of the list, so the tail pointer is updated to point to this new element. When an element is removed (dequeued), it is removed from the head of the list, so the head pointer is updated to point to the next element.

Here is a simple implementation in Python:

```python
class Node:
def __init__(self, data=None):
self.data = data
self.next = None

class Queue:
def __init__(self):
self.head = None
self.tail = None

def enqueue(self, data):
new_node = Node(data)
if self.tail is None:
self.head = self.tail = new_node
return
self.tail.next = new_node
self.tail = new_node

def dequeue(self):
if self.head is None:
return
temp = self.head
self.head = temp.next
if self.head is None:
self.tail = None
return str(temp.data)
```

In this code, the `Node` class represents an element in the linked list, with a `data` attribute for the element's value and a `next` attribute for the reference to the next element. The `Queue` class represents the queue, with a `head` and a `tail` attribute for the pointers to the first and last elements in the queue, and `enqueue` and `dequeue` methods for adding and removing elements.