Exercise for Olo

Toppings.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.Http;
using System.Text;
using System.Threading.Tasks;
using Newtonsoft.Json;

namespace Inteview_Exercise_Toppings
{
    class Program
    {
        static void Main(string[] args)
        {

            var httpClient = new HttpClient();
            var response = httpClient.GetAsync("http://files.olo.com/pizzas.json").Result.Content.ReadAsStringAsync().Result;
            var pizzaOrders = JsonConvert.DeserializeObject<List<Pizza>>(response);

            Dictionary<List<string>, int> toppings = new Dictionary<List<string>, int>(new ToppingComparer());

            pizzaOrders.ForEach(pizza =>
            {
                if (!toppings.ContainsKey(pizza.Toppings))
                    toppings.Add(pizza.Toppings, 1);
                else
                    toppings[pizza.Toppings] += 1;
            });

            var top20 = toppings.OrderByDescending(x => x.Value).Take(20).ToList();

            top20.ForEach(topping =>
            {
                Console.WriteLine($"{String.Join(",", topping.Key)} is number {top20.IndexOf(topping)+1} with {topping.Value} orders.");
            });
        }
    }

    class ToppingComparer : IEqualityComparer<List<string>>
    {
        public bool Equals(List<string> x, List<string> y)
        {
            return x.SequenceEqual(y);
        }

        public int GetHashCode(List<string> obj)
        {
            int hashcode = 0;

            foreach (var item in obj)
            {
                hashcode ^= item.GetHashCode();
            }

            return hashcode;
        }
    }

    class Pizza
    {
        public List<string> Toppings = new List<string>();
    }
}

pepperoni is #1 with 4616 orders.
mozzarella cheese is #2 with 1014 orders.
four cheese is #3 with 956 orders.
bacon is #4 with 732 orders.
beef is #5 with 623 orders.
sausage is #6 with 402 orders.
italian sausage is #7 with 361 orders.
chicken is #8 with 229 orders.
ham is #9 with 165 orders.
mushrooms is #10 with 159 orders.
black olives is #11 with 117 orders.
pepperoni,four cheese is #12 with 103 orders.
alredo sauce is #13 with 101 orders.
four cheese,pepperoni is #14 with 100 orders.
mozzarella cheese,pepperoni is #15 with 96 orders.
cheddar cheese is #16 with 95 orders.
pineapple is #17 with 79 orders.
pepperoni,beef is #18 with 67 orders.
pepperoni,bacon is #19 with 63 orders.
pepperoni,mozzarella cheese is #20 with 59 orders.