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from __future__ import annotations

from collections import deque

from dataclasses import dataclass, field

@dataclass

class StackWithQueues:

"""

https://www.geeksforgeeks.org/implement-stack-using-queue/

>>> stack = StackWithQueues()

>>> stack.push(1)

>>> stack.push(2)

>>> stack.push(3)

>>> stack.peek()

>>> stack.pop()

>>> stack.peek()

>>> stack.pop()

>>> stack.peek() is None

True

>>> stack.pop()

Traceback (most recent call last):

...

IndexError: pop from an empty deque

"""

main_queue: deque[int] = field(default_factory=deque)

temp_queue: deque[int] = field(default_factory=deque)

def push(self, item: int) -> None:

self.temp_queue.append(item)

while self.main_queue:

self.temp_queue.append(self.main_queue.popleft())

self.main_queue, self.temp_queue = self.temp_queue, self.main_queue

def pop(self) -> int:

return self.main_queue.popleft()

def peek(self) -> int | None:

return self.main_queue[0] if self.main_queue else None

if __name__ == "__main__":

import doctest

doctest.testmod()

stack: StackWithQueues | None = StackWithQueues()

while stack:

print("\nChoose operation:")

print("1. Push")

print("2. Pop")

print("3. Peek")

print("4. Quit")

choice = input("Enter choice (1/2/3/4): ")

if choice == "1":

element = int(input("Enter an integer to push: ").strip())

stack.push(element)

print(f"{element} pushed onto the stack.")

elif choice == "2":

popped_element = stack.pop()

if popped_element is not None:

print(f"Popped element: {popped_element}")

else:

print("Stack is empty.")

elif choice == "3":

peeked_element = stack.peek()

if peeked_element is not None:

print(f"Top element: {peeked_element}")

else:

print("Stack is empty.")

elif choice == "4":

del stack

stack = None

else:

print("Invalid choice. Please try again.")

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