# Leetcode 225 - Implement stack using queues

`Note:`

- Because we are using queues, we can only use
`push`

and`shift`

(To get the first element). - DO NOT use
`pop`

. - One queue is enough for implementation.

`Question:`

Implement a last-in-first-out (LIFO) stack using only two queues. The implemented stack should support all the functions of a normal stack (push, top, pop, and empty).

Implement the MyStack class:

- void push(int x) Pushes element x to the top of the stack.
- int pop() Removes the element on the top of the stack and returns it.
- int top() Returns the element on the top of the stack.
- boolean empty() Returns true if the stack is empty, false otherwise.

Notes:

You must use only standard operations of a queue, which means that only push to back, peek/pop from front, size and is empty operations are valid.

Depending on your language, the queue may not be supported natively. You may simulate a queue using a list or deque (double-ended queue) as long as you use only a queue’s standard operations.

`Example:`

1 | Input |

`Code:`

1 | var MyStack = function() { |