CC150 3.5 Class Beta

MyQueue.h.cpp

/* CC150 3.5
 * Implement a MyQueue class which implements a queue using two stacks.
 */

#ifndef MYQUEUEBETA_H
#define MYQUEUEBETA_H

#include <iostream>
#include <stack>

using namespace std;

class MyQueue{
public: // Only keep track of the oldest element since it's a queue!
	int front(); // returns the next element in the queue
	void enqueue(int data); // inserts a new element at the end of the queue
	int dequeue(); // removes the next element in the queue and returns the new next element
private:
	stack<int> stackIn;
	stack<int> stackOut;
	void stackShift();
};

int MyQueue::front()
{
	stackShift();
	if (!stackOut.empty())
		return stackOut.top();
	else
		return -1;
}

void MyQueue::enqueue(int data)
{
	stackIn.push(data); // push data
	return;
}

int MyQueue::dequeue()
{
	stackShift();
	if (stackOut.empty())
		return -1;
	int data = stackOut.top(); // pop data
	stackOut.pop();
	return data;
}

void MyQueue::stackShift()
{
	if (stackOut.empty()) {
		while (!stackIn.empty()) {
			stackOut.push(stackIn.top());
			stackIn.pop();
		}
	}
}

#endif