5b) Queue using stack(dequeue expensive).cpp

#include<iostream>
#include<stack>
// Dequeue is expensive
using namespace std;
// Just change the property of stack 
class Queue{
    int size;
    stack<int> st1,st2;
    public:
        Queue(){
            size = 0;
        }
        void enqueue(int);
        int dequeue();
        bool isempty();
        int getSize();


};

int Queue :: getSize(){
    return size;
}
bool Queue :: isempty(){
    return (st1.empty());
}
void Queue :: enqueue(int val){
    size++;
    st1.push(val);
    
}

int Queue :: dequeue(){
    // Simply pop out the elements
    if(st1.empty()){
        return -1;

    }
    else{
        size--;
        while(!st1.empty()){
            st2.push(st1.top());
            st1.pop();
        }
        // Now pop elements
        int top_ele = st2.top();
        st2.pop();

        // Retranfer the contents into st2 from st1
        while(!st2.empty()){
            st1.push(st2.top());
            st2.pop();
        }

        return top_ele;
    }
    
    
}


void display(Queue q){
    Queue tempqueue = q ;
    while(!tempqueue.isempty()){
        cout << tempqueue.dequeue() << " ";
        
    }
    cout << endl;
}
int main(){

    Queue qu;
    for(int i=1;i<=5;i++){
        qu.enqueue(i);
    }
    display(qu);
    cout << qu.dequeue() << " got dequeued" << endl;
    display(qu);
    cout << "Size of Queue is : " << qu.getSize() << endl;

    

    return 0;
}