Псевдокод Супермаркет.cs

using System;
using System.Collections.Generic;

class Program
{
    static void Main(string[] args)
    {
        ClientsFactory factory = new ClientsFactory();
        Supermarket supermarket = new Supermarket();

        supermarket.Run(factory.GenerateClients());
    }
}

class ClientsFactory
{
    public Queue<Client> GenerateClients()
    {
        int maxClients = 5;
        Queue<Client> clients = new Queue<Client>();

        int minBalance = 10;
        int maxBalance = 50;
        
        for (int i = 0; i < maxClients; i++)
        {
            int money = UserUtils.GetRandomNumber(minBalance, maxBalance);
            clients.Enqueue(new Client(money));
        }

        return clients;
    }
}

class Supermarket
{
    Queue<Client> _clients;
    List<Product> _products;

    public Supermarket()
    {
        _products = new List<Product>()
        {
            new Product(10),
            new Product(10),
            new Product(10),
            new Product(10),
        };
    }

    public void Run(Queue<Client> clients)
    {
        _clients = new Queue<Client>(clients);

        ProcessShopping();

        ServeClients();
    }

    private void ServeClients()
    {
        while (_clients.Count > 0)
        {
            Client client = _clients.Dequeue();

            while (client.CanPay == false)
                client.RemoveRandomProduct();
        }
    }

    private void ProcessShopping()
    {
        foreach (Client client in _clients)
        {
            int maxClients = 5;
            int repeats = UserUtils.GetRandomNumber(maxClients);

            for (int i = 0; i < repeats; i++)
            {
                int randomProductIndex = UserUtils.GetRandomNumber(_products.Count);
                Product product = _products[randomProductIndex];

                client.Add(product);
            }
        }
    }
}

class Client
{
    private readonly List<Product> _products;
    private readonly int _money;

    public Client(int money)
    {
        _money = money;
        _products = new List<Product>();
    }

    public bool CanPay => _money > GetTotalPrice();

    public void Add(Product product)
    {
        _products.Add(product);
    }

    public void RemoveRandomProduct()
    {
        int randomIndex = UserUtils.GetRandomNumber(_products.Count);
        _products.RemoveAt(randomIndex);
    }

    private int GetTotalPrice()
    {
        int sum = 0;

        foreach (var item in _products)
        {
            sum += item.Price;
        }

        return sum;
    }
}

class Product
{
    public Product(int price)
    {
        Price = price;
    }

    public int Price { get; }
}

class UserUtils
{
    private static readonly Random s_random = new Random();

    public static int GetRandomNumber(int minValue, int maxValue)
    {
        return s_random.Next(minValue, maxValue);
    }

    public static int GetRandomNumber(int maxValue)
    {
        return s_random.Next(maxValue);
    }
}