13.1

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;


public class Bread : ProductPrototype
{
    public Bread(decimal price) : base(price) { }

    public override ProductPrototype Clone()
    {
        return (ProductPrototype)this.MemberwiseClone();

    }
}

public class Milk : ProductPrototype
{
    public Milk(decimal price) : base(price) { }

    public override ProductPrototype Clone()
    {
        return (ProductPrototype)this.MemberwiseClone();
    }
}


public abstract class ProductPrototype
{
    public decimal Price { get; set; }

    public ProductPrototype(decimal price)
    {
        Price = price;
    }

    public abstract ProductPrototype Clone();
}


public class Supermarket
{
    private Dictionary<string, ProductPrototype> _productList = new Dictionary<string, ProductPrototype>();

    public void AddProduct(string key, ProductPrototype productPrototype)
    {
        _productList.Add(key, productPrototype);
    }

    public ProductPrototype GetProduct(string key)
    {
        return _productList[key].Clone();
    }
}


class MainClass
{
    public static void Main(string[] args)
    {

        var supermarket = new Supermarket();

        supermarket.AddProduct("Milk", new Milk(0.89m));
        supermarket.AddProduct("Bread", new Bread(1.10m));

        decimal sourcePrice;
        decimal currentPrice;

        var clonedMilk = (Milk)supermarket.GetProduct("Milk");
        sourcePrice = clonedMilk.Price;
        clonedMilk.Price = 0.85m;
        currentPrice = clonedMilk.Price;
        Console.WriteLine(String.Format("Milk - {0} > {1}", sourcePrice, currentPrice));

        var clonedBread = (Bread)supermarket.GetProduct("Bread");
        sourcePrice = clonedBread.Price;
        clonedBread.Price = 0.99m;
        currentPrice = clonedBread.Price;
        Console.WriteLine(String.Format("Bread - {0} > {1}", sourcePrice, currentPrice));

    }
}