How can I implement queues and stacks in my code?

How can I implement queues and stacks in my code?

You can implement queues and stacks using arrays or linked lists. Would you like a code example for one of these?

Yes, please provide a code example for a stack using an array.

Sure! Here's a simple implementation of a stack using an array in Python:

class Stack:
    def __init__(self):
        self.items = []

    def push(self, item):
        self.items.append(item)

    def pop(self):
        return self.items.pop() if not self.is_empty() else None

    def is_empty(self):
        return len(self.items) == 0

    def peek(self):
        return self.items[-1] if not self.is_empty() else None

    def size(self):
        return len(self.items)

What about implementing a queue using a linked list?

Here's a simple implementation of a queue using a linked list in Python:

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

class Queue:
    def __init__(self):
        self.front = None
        self.rear = None

    def enqueue(self, item):
        new_node = Node(item)
        if self.rear:
            self.rear.next = new_node
        self.rear = new_node
        if not self.front:
            self.front = new_node

    def dequeue(self):
        if self.front:
            data = self.front.data
            self.front = self.front.next
            if not self.front:
                self.rear = None
            return data
        return None

    def is_empty(self):
        return self.front is None