#include <iostream>
using namespace std;

class Consumer
{
protected:
    int id;
    string name;
    int prevReading, currReading;

public:
    void getData()
    {
        cout << "Enter consumer id: ";
        cin >> id;
        cout << "Enter name: ";
        cin >> name;
        cout << "Enter previous reading: ";
        cin >> prevReading;
        cout << "Enter current reading: ";
        cin >> currReading;
        while (currReading < prevReading)
        {
            cout << "Current reading cannot be less than previous. Enter again: ";
            cin >> currReading;
        }
    }

    int units()
    {
        return currReading - prevReading;
    }

    int getId()
    {
        return id;
    }

    virtual float bill() = 0;
    virtual string type() = 0;

    void showBill()
    {
        cout << "\n-------- ELECTRICITY BILL --------" << endl;
        cout << "Consumer ID   : " << id << endl;
        cout << "Name          : " << name << endl;
        cout << "Type          : " << type() << endl;
        cout << "Units consumed: " << units() << endl;
        cout << "Bill amount   : Rs. " << bill() << endl;
        cout << "----------------------------------" << endl;
    }

    virtual ~Consumer() {}
};

class Domestic : public Consumer
{
public:
    float bill()
    {
        int u = units();
        float amt;
        if (u <= 100)
            amt = u * 3.5;
        else if (u <= 300)
            amt = 100 * 3.5 + (u - 100) * 5.0;
        else
            amt = 100 * 3.5 + 200 * 5.0 + (u - 300) * 7.5;
        return amt + 50;
    }
    string type()
    {
        return "Domestic";
    }
};

class Commercial : public Consumer
{
public:
    float bill()
    {
        int u = units();
        float amt;
        if (u <= 200)
            amt = u * 7.0;
        else
            amt = 200 * 7.0 + (u - 200) * 9.5;
        return amt + 150;
    }
    string type()
    {
        return "Commercial";
    }
};

class Industrial : public Consumer
{
public:
    float bill()
    {
        return units() * 8.5 + 500;
    }
    string type()
    {
        return "Industrial";
    }
};

int main()
{
    Consumer *list[50];
    int n = 0, ch, t, id;

    do
    {
        cout << "\n===== Electricity Billing System =====" << endl;
        cout << "1. Add consumer" << endl;
        cout << "2. Show all bills" << endl;
        cout << "3. Search by consumer id" << endl;
        cout << "4. Exit" << endl;
        cout << "Enter choice: ";
        cin >> ch;

        switch (ch)
        {
        case 1:
            if (n >= 50)
            {
                cout << "Limit reached" << endl;
                break;
            }
            cout << "1. Domestic  2. Commercial  3. Industrial" << endl;
            cout << "Enter type: ";
            cin >> t;
            if (t == 1)
                list[n] = new Domestic;
            else if (t == 2)
                list[n] = new Commercial;
            else if (t == 3)
                list[n] = new Industrial;
            else
            {
                cout << "Invalid type" << endl;
                break;
            }
            list[n]->getData();
            n++;
            cout << "Consumer added" << endl;
            break;

        case 2:
            if (n == 0)
                cout << "No records" << endl;
            for (int i = 0; i < n; i++)
                list[i]->showBill();
            break;

        case 3:
        {
            cout << "Enter consumer id: ";
            cin >> id;
            bool found = false;
            for (int i = 0; i < n; i++)
            {
                if (list[i]->getId() == id)
                {
                    list[i]->showBill();
                    found = true;
                }
            }
            if (!found)
                cout << "Consumer not found" << endl;
            break;
        }

        case 4:
            cout << "Exiting..." << endl;
            break;

        default:
            cout << "Invalid choice" << endl;
        }
    } while (ch != 4);

    for (int i = 0; i < n; i++)
        delete list[i];

    return 0;
}