Stack & Queues - Queues: A Tale of Two Stacks [M]

 In this challenge, you must first implement a queue using two stacks. Then process  queries, where each query is one of the following  types:

1. 1 x: Enqueue element  into the end of the queue.
2. 2: Dequeue the element at the front of the queue.
3. 3: Print the element at the front of the queue.

Sample Input

10

1 42

2

1 14

3

1 28

3

1 60

1 78

2

2

Sample Output

14

14

Explanation

 public static class MyQueue<T> {

        Stack<T> stackNewestOnTop = new Stack<T>();

        Stack<T> stackOldestOnTop = new Stack<T>();

        public void enqueue(T value) { // Push onto newest stack

            stackNewestOnTop.push(value);

        }

        public T peek() {

              prepOld();

             return stackOldestOnTop.peek();

        }

        public T dequeue() {

            prepOld();

            return stackOldestOnTop.pop();

        }

        

        public void prepOld(){

            if (stackOldestOnTop.isEmpty())

                while(!stackNewestOnTop.isEmpty())

                    stackOldestOnTop.push(stackNewestOnTop.pop());

        }

    }