using System;

using System.Collections.Generic;

​

public interface ICheckout

{

    void Scan(string item);

    int GetTotal();

}

​

public class Item

{

    public Item(string sku, int price, int specialPrice = 0, int specialCount = 0)

    {

        this.Sku = sku;

        this.Price = price;

        this.SpecialPrice = specialPrice;

        this.SpecialCount = specialCount;

    }

​

    public string Sku;

    public int Price;

    public int SpecialPrice;

    public int SpecialCount;

    public int getDiscountedPrice(int itemCount)

    {

        try

        {

            int individualItems = itemCount;

            int specialItemCount = 0;

            if (this.SpecialCount > 0)

            {

                individualItems = itemCount % this.SpecialCount;

                specialItemCount = (itemCount - individualItems) / this.SpecialCount;

            }

​

            return (individualItems * this.Price) + (specialItemCount * this.SpecialPrice);

        }

        catch (Exception e)

        {

            Console.WriteLine(e.Message);

            return 0;

        }

    }

}

​

public class Checkout : ICheckout

{

    public List<Item> Items;

    public List<Item> ScannedItems;

    public Checkout()

    {

        this.Items = new List<Item>();

        this.ScannedItems = new List<Item>();

    }

​

    public void Scan(string item)

    {

        if (this.Items == null || this.Items.Count == 0)

        {

            return;

        }

​

        for (int i = 0; i < this.Items.Count; i++)

        {

            Item currentItem = this.Items[i];

            if (currentItem != null && currentItem.Sku == item)

            {

                this.ScannedItems.Add(currentItem);

                return;

            }

        }

    }

​

    public int GetTotal()

    {

        int totalPrice = 0;

        if (this.ScannedItems == null || this.ScannedItems.Count == 0)

        {

            return totalPrice;

        }

​

        // Get the distinct SKUs from scanned items.   ====>>  ["A", "B", "C"]

        List<Item> distinctSkus = this.getDistinctItems();

        for (int i = 0; i < distinctSkus.Count; i++)

        {

            Item currentItem = distinctSkus[i];

            int currentSkuCount = getCountForSku(currentItem.Sku);

            totalPrice += currentItem.getDiscountedPrice(currentSkuCount);

        }

​

        return totalPrice;

    }

​

    public List<Item> getDistinctItems()

    {

        // initialise the list of distinct SKUs

        List<Item> distinctItems = new List<Item>();

        // null check, return empty list if invalid

        if (this.ScannedItems == null || this.ScannedItems.Count == 0)

        {

            return distinctItems;

        }

​

        // iterate the list and insert distinct SKUs

        for (int i = 0; i < this.ScannedItems.Count; i++)

        {

            Item scannedItem = this.ScannedItems[i];

            if (!distinctItems.Contains(scannedItem))

            {

                distinctItems.Add(scannedItem);

            }

        }

​

        return distinctItems;

    }

​

    public int getCountForSku(string sku)

    {

        int skuCount = 0;

        // null check, return empty list if invalid

        if (this.ScannedItems == null || this.ScannedItems.Count == 0)

        {

            return skuCount;

        }

​

        // iterate the list and insert distinct SKUs

        for (int i = 0; i < this.ScannedItems.Count; i++)

        {

            Item scannedItem = this.ScannedItems[i];

            if (scannedItem.Sku == sku)

            {

                ++skuCount;

            }

        }

​

        return skuCount;

    }

​

    public void addItem(Item item)

    {

        this.Items.Add(item);

    }

}

​

Checkout checkout = new Checkout();

checkout.addItem(new Item("A", 50, 130, 3));

checkout.addItem(new Item("B", 30, 45, 2));

checkout.addItem(new Item("C", 20, 0, 0));

checkout.addItem(new Item("D", 15, 0, 0));

string decision = "1";

do

{

    Console.WriteLine("Please scan the item");

    string Sku = Console.ReadLine();

    checkout.Scan(Sku);

    Console.WriteLine("Press 1 to scan more items or press ...");

    decision = Console.ReadLine();

}

while (decision == "1");

Console.WriteLine("");

Console.WriteLine("");

Console.WriteLine("Total Price is -");

Console.WriteLine("");

Console.WriteLine(checkout.GetTotal());