JuniorTheoryCommon

What does the program print?

Python

from collections import deque

stack = [1, 2, 3]
queue = deque([1, 2, 3])
print(stack.pop(), queue.popleft())

3 1

Expecting pop() to take the first item, like a queue: without an argument list.pop removes the last one, which is how a list works as a stack.
Expecting popleft to take from the right end: left is the start of the deque, so it returns 1, the item added first.

JuniorTheoryCommon

Python

from collections import deque

stack = [1, 2, 3]
queue = deque([1, 2, 3])
print(stack.pop(), queue.popleft())

3 1

Expecting pop() to take the first item, like a queue: without an argument list.pop removes the last one, which is how a list works as a stack.
Expecting popleft to take from the right end: left is the start of the deque, so it returns 1, the item added first.