MyStack

All Implemented Interfaces:
```
public final class MyStack

                    
```
225 - Implement Stack using Queues\.
Easy
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 "MyStack", "push", "push", "top", "pop", "empty" [ [], 1, 2, [], [], []]
Output: null, null, null, 2, 2, false
Explanation:
```
MyStack myStack = new MyStack();
myStack.push(1);
myStack.push(2);
myStack.top(); // return 2
myStack.pop(); // return 2
myStack.empty(); // return False
```
Constraints:
- 1 <= x <= 9
- At most 100 calls will be made to push, pop, top, and empty.
- All the calls to pop and top are valid.
Follow-up: Can you implement the stack using only one queue?

Nested Class Summary

Nested Classes
Modifier and Type	Class	Description

Field Summary

Fields
Modifier and Type	Field	Description

Constructor Summary

Constructors
Constructor	Description
`MyStack()`

Enum Constant Summary

Enum Constants
Enum Constant	Description

Method Summary

Modifier and Type	Method	Description
`final Unit`	`push(Integer x)`
`final Integer`	`pop()`
`final Integer`	`top()`
`final Boolean`	`empty()`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail
- MyStack
```
MyStack()
```

Method Detail

push
```
 final Unit push(Integer x)
```

pop
```
 final Integer pop()
```

top
```
 final Integer top()
```

empty
```
 final Boolean empty()
```