When working with Python, there may be times when you need to implement a push back-like function. This function allows you to add elements to a collection and retrieve them in reverse order. In this article, we will explore three different ways to solve this problem using Python.

Option 1: Using a List

One way to implement a push back-like function in Python is by using a list. Lists in Python are mutable and allow you to add elements to the end using the append() method. To retrieve elements in reverse order, you can use the pop() method with a negative index.

class PushBack:
    def __init__(self):
        self.collection = []

    def push(self, element):
        self.collection.append(element)

    def pop_back(self):
        if self.collection:
            return self.collection.pop(-1)
        else:
            return None

In this implementation, we define a class called PushBack with two methods: push() to add elements to the collection and pop_back() to retrieve elements in reverse order. The pop_back() method checks if the collection is empty before popping the last element. If the collection is empty, it returns None.

Option 2: Using a Deque

Another way to solve this problem is by using a deque (double-ended queue) from the collections module. A deque is similar to a list but provides efficient append and pop operations on both ends.

from collections import deque

class PushBack:
    def __init__(self):
        self.collection = deque()

    def push(self, element):
        self.collection.append(element)

    def pop_back(self):
        if self.collection:
            return self.collection.pop()
        else:
            return None

In this implementation, we import the deque class from the collections module. The PushBack class uses a deque instead of a list for the collection. The pop_back() method now uses the pop() method without any arguments to retrieve elements from the end of the deque.

Option 3: Using a Stack

A third option to solve this problem is by using a stack data structure. A stack follows the Last-In-First-Out (LIFO) principle, which makes it suitable for implementing a push back-like function.

class PushBack:
    def __init__(self):
        self.collection = []

    def push(self, element):
        self.collection.append(element)

    def pop_back(self):
        if self.collection:
            return self.collection.pop()
        else:
            return None

In this implementation, we use a list as the underlying data structure for the stack. The push() method adds elements to the end of the list, and the pop_back() method retrieves elements from the end of the list using the pop() method.

After exploring these three options, it is clear that using a deque from the collections module is the best choice. Deques provide efficient append and pop operations on both ends, making them well-suited for implementing a push back-like function. Additionally, the pop() method without any arguments retrieves elements from the end of the deque, simplifying the code.