Stack Using Queues | Dataford Interview Questions

Unity Editor records actions in LIFO order for an undo-style command history. Implement this stack behavior using exactly one queue and queue operations only.

Write process_stack_operations(operations). Each operation is one of:

["push", value]: Add integer value to the top of the stack.
["pop"]: Remove and return the top value.
["top"]: Return the top value without removing it.
["empty"]: Return whether the stack contains no values.

Return an array containing outputs for every pop, top, and empty operation, in order. push operations produce no output. You may assume pop and top are never called on an empty stack.

A Python collections.deque may be used as the queue, but access it only through append, popleft, and len.

Constraints

1 <= operations.length <= 10^4
Each push value is an integer in [-10^9, 10^9]
pop and top are called only when the simulated stack is nonempty
Use exactly one queue and queue operations only

Function Signature

def process_stack_operations(operations):

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