50_Queue_Using_Stacks.cpp

#include<iostream>
#include<stack>
#include"38_Stack_LinkedList.cpp"
using namespace std;
stack<int> s1,s2;
// Dequeue is expensive
void dequeue(){
    if(!s1.empty() && s2.empty()){
        while(!s1.empty()){
            s2.push(s1.top());
            s1.pop();
        }
        s2.pop();
         while(!s2.empty()){
            s1.push(s2.top());
            s2.pop();
        }
    }
    else{
        cout<<"Queue is empty"<<endl;
    }

}
void enqueue(int val){
    s1.push(val);
}
void display(){
     if(!s1.empty() && s2.empty()){
        while(!s1.empty()){
            s2.push(s1.top());
            s1.pop();
        }
         while(!s2.empty()){
            cout<<s2.top()<<" ";;
            s1.push(s2.top());
            s2.pop();
        }
        cout<<endl;
    }
    else{
        cout<<"Queue is empty"<<endl;
    }
}
int main()
{
    enqueue(10);
    enqueue(20);
    enqueue(30);
    enqueue(40);
    enqueue(50);
    display();
    dequeue();
    display();
    dequeue();
    display();
    dequeue();
    display();
    return 0;
}