C3P5.java

package chapter3;

import java.util.Stack;

/*
 * Career Cup 3.5
 * Implement a MyQueue class which implements a queue using two stacks.
 */
public class C3P5 {

  static class MyQueue {
		Stack<Integer> enqueueStack = new Stack<Integer>();
		Stack<Integer> dequeueStack = new Stack<Integer>();

		public void enqueue(int data) {
			enqueueStack.push(data);
		}

		public int pop() {
			if (dequeueStack.isEmpty())
				while (!enqueueStack.isEmpty())
					dequeueStack.push(enqueueStack.pop());
			
			return dequeueStack.pop();
		}

	}

	public static void main(String[] args) {
		MyQueue queue = new MyQueue();
		queue.enqueue(1);
		queue.enqueue(2);
		queue.enqueue(3);
		System.out.println(queue.pop());
		System.out.println(queue.pop());
		System.out.println(queue.pop());
	}

}