Adv2018/D14.1/Program.cs

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

namespace D14._1
{
    class Program
    {
        static void Main(string[] args)
        {
            if (args.Length == 0) return;
            int input = int.Parse(args[0]);

            int elf1 = 0;
            int elf2 = 1;

            List<int> recipes = new List<int>() { 3, 7 };

            for (int _ = 0; _ < 10 + input; ++_)
            {
                int nrecipe = recipes[elf1] + recipes[elf2];
                if (nrecipe < 10) recipes.Add(nrecipe);
                else recipes.AddRange(new[] { 1, nrecipe - 10 });

                elf1 = (elf1 + 1 + recipes[elf1]) % recipes.Count;
                elf2 = (elf2 + 1 + recipes[elf2]) % recipes.Count;
            }

            string result = "";
            for (int i = input; i < 10 + input; ++i)
                result += recipes[i].ToString();

            Console.WriteLine(result);
        }
    }
}