Interview Question for Software Engineer / Developers

Country: Russia
Interview Type: In-Person

Comment hidden because of low score. Click to expand.
of 2 vote

public class StackBy2Queues<E> {

	private Queue<E> queue1 = new LinkedList<E>();
	private Queue<E> queue2 = new LinkedList<E>();;

	public boolean empty() {

		return queue2.isEmpty() && queue1.isEmpty();

	public E peek() {
		if (queue2.isEmpty())
			return queue1.peek();
		return queue2.peek();


	public synchronized int size() {
		return queue2.size() + queue1.size();

	public synchronized E pop() {
		if (queue2.isEmpty())
			return queue1.poll();
		return queue2.poll();

	public synchronized E push(E item) {
		if (queue2.isEmpty()) {
			return item;
		// Move all elements from queue1 to queue2 and swap
		Queue<E> q = queue1;
		queue1 = queue2;
		queue2 = q;
		return item;

	public static void main(String[] args) {
		StackBy2Queues<Integer> myStack = new StackBy2Queues<>();
		for (int i = 0; i < 10; i++) {
		System.out.println("Stack items count:" + myStack.size());
		int order = 1;
		while (!myStack.empty()) {
			System.out.println("Poped [" + order + "]: " + myStack.pop());



- artak.a.petrosyan November 20, 2015 | Flag Reply

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