Good morning! Here's our prompt for today.

Building a Queue with Two Stacks: A Challenge in Engineering Elegance

The Objective: Queue with Stacks

In this challenge, your task is to implement a queue using two stacks. While many programming languages offer queues through arrays or lists, we're restricting our approach to only utilize stacks.

The end result should behave like this:

1const tsq = new TwoStackQueue();
2tsq.push(1);
3tsq.push(2);
4tsq.pop();  // Should return 1
5tsq.pop();  // Should return 2

The Blueprint: Visualizing the Mechanics

Imagine having two stacks that work in harmony to simulate a queue. These stacks are like two components of a complex machine, each with its own specific role.

Constraints and Expectations

Let's clarify the rules of the game:

• Number of Operations: The maximum number of operations won't exceed 100,000.
• Value Ranges: The elements you push onto the stack will range between -1,000,000,000 and 1,000,000,000.
• Time Complexity for Push: If the pop operation has a time complexity of O(n), then the push operation should be O(1). Otherwise, the time complexity for push should be O(n).
• Time Complexity for Pop: If the push operation has a time complexity of O(n), then the pop operation should be O(1). Otherwise, it should be O(n).
• Space Complexity: Expected to be O(n).

Try to solve this here or in Interactive Mode.

How do I practice this challenge?

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class TwoStackQueue:

    def __init__(self):

        self.inbox = []

        self.outbox = []

​

    def push():

        # fill in

        return

​

    def pop():

        # fill in

        return

​

​

import unittest

​

​

class Test(unittest.TestCase):

    def test_1(self):

        tsq = TwoStackQueue()

        tsq.push(1)

        tsq.push(2)

        tsq.pop()

        assert tsq.pop() == 2

        print(

            "PASSED: Pushing `1` and `2` into a `TwoStackQueue` should pop `1` and then `2`."

        )

​

    def test_2(self):

Here's our guided, illustrated walk-through.

How do I use this guide?