leetcode-solutions-1/QueueUsingTwoStacks.cpp at master · kishanrajput23/leetcode-solutions-1 · GitHub

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#include<iostream>
#include<stack>
using namespace std;

class que{
    stack<int> s1;
    stack<int> s2;

    public:
    void push(int x){
        s1.push(x);
    }

    int pop(){
        if(s1.empty() and s2.empty()){
            cout<<"Queue is empty"<<endl;
            return -1;
        }

        if(s2.empty()){
            while(!s1.empty()){
                s2.push(s1.top());
                s1.pop();
            }
        }
        int ans = s2.top();
        s2.pop();
        return ans;
    }

    bool empty(){
        if(s1.empty() and s2.empty()){
            return true;
        }
        return false;
    }
};

int main(){

    que q;
    q.push(1);
    q.push(2);
    q.push(3);
    q.push(4);
    cout<<q.pop()<<endl;
    q.push(5);
    cout<<q.pop()<<endl;
    cout<<q.pop()<<endl;
    cout<<q.pop()<<endl;
    cout<<q.pop();
    cout<<q.pop()<<endl;
    cout<<q.empty();
    return 0;
}