Queue_using_single_Stack.cpp

/* @author [saqlain] (https://github.com/Mysterious786)
 * @file
 *
 * Implementation of a Queue using Single Stacks.
 */
#include <iostream>
#include <stack>
#include <cstdlib>
#include<queue>
using namespace std;
     /**
     * Queue data structure.Store elements in FIFO
     * (first-in-first-out) manner.
     *
     */
      class Queue
    {
        std::stack<int> s;
          public:
        /**
         * Pushes data to the back of queue
         */
        void enqueue(int data){
         /**
             *  Push item into the First Stack
             */
            s.push(data);
        }
           /**
         * Remove an item from the queue
         */
        int dequeue()
        {
            /**
             * Determines whether the stack is empty
             */
            if (s.empty())
            {
                cout << "Underflow!!";
                exit(0);
            }
              /**
             *Removes item from the Stack
             */
            int top = s.top();
            s.pop();
             /**
             * Determines whether the stack becomes empty,and returns the popped item
             */
            if (s.empty())
            {
                return top;
            }
   /**
             * Recursion call
             */
            int item = dequeue();
              /**
             * push popped item back into the stack
             */
            s.push(top);
               /**
             * return the result of dequeue() call
             */
            return item;
        }
    };

/**
 * Main function, calls enqueue and dequeue
 */
int main()
{
    int keys[] = {1, 2, 3, 4, 5};
     Queue q;
    /**
     * Adding key to the Queue
     */

    for (int key : keys)
    {
        q.enqueue(key);
    }
    /**
     * Print
     *
     */
    cout << q.dequeue() << " ";
    cout << q.dequeue() << " ";
      return 0;
}