#include <iostream>
using namespace std;
class queue {
public:
    int* a, r, size;

    queue() {
        r = 0;
        cout << "\nEnter size of the Queue\n";
        cin >> size;
        cout << "\n\n";

        a = new int[size];
    }

    int isempty();
    int isfull();
    int push();
    int pop();
    int display();
};

/**
 * Check if the array is empty.
 */
int queue::isempty() {
    if (r == -1)
        return 1;

    return 0;
}

/**
 * Check if the array is full.
 */
int queue::isfull() {
    if (r == (size))
        return 1;

    return 0;
}

/**
 * Insert a value to the array.
 */
int queue::push() {
    if (isfull()) {
        cout << "\nQueue Overflow\n\n";
        return 0;

    }
    else {
        cout << "\nEnter an element: ";
        int val;
        cin >> val;
        a[r] = val;
        cout << val << " has been successfully added \n\n";
        r++;
        display();
    }
}

/**
 * Remove the last element of the array.
 */
int queue::pop() {
    if (isempty()) {
        cout << "\n\nQueue Overflow\n";
        return 0;
    }

    cout << a[r-1] << " has been removed.";
    for (int i = 0; i <= r; i++) {
        a[i] = a[i];
    }
    r--;
    display();
    cout << "Element deleted sucessfully\n";
}

/**
 * Print all the items inside the array.
 */
int queue::display() {
    if (isempty()) {
        cout << "\n\n\nQueue is empty -- No Element to display\n";
        return 0;
    }
    else {
        cout << "\n==================================\n";
        cout << "Items in Queue:\n";
        cout << "==================================\n";
        for (int i = 0; i < r; i++) {
            cout << "[" << i << "] | " << a[i] << "\n";
            cout << "----------------------------------\n";
        }
        cout << "\n";
    }
}

/**
 * Main function.
 */
int main() {
    int i = 0, s;
    queue q;
    while (i != 1) {
        cout << "\n********* MENU *******\n";
        cout << "\n1. Push\n2. Pop\n3. Display\n4. Exit\n";
        cout << "\n********* MENU *******\n";
        cout << "Enter your option: ";
        cin >> s;
        switch (s) {
            case 1:
                q.push();
                break;
            case 2:
                q.pop();
                break;
            case 3:
                q.display();
                break;
            case 4:
                i = 1;
                break;
            default:
                cout << "\nEnter correct option\n|";
                break;
        }
    }
    return 0;
}