AdventOfCodeDay15.cs

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

namespace AdventOfCodeDay15
{
	class Program
	{
		static void Main(string[] args)
		{
			var ss = new StreamReader("../../input1.txt");
			//var ss = new StreamReader("../../input-test.txt");

			string line;
			var input = new List<string>();
			while ((line = ss.ReadLine()) != null)
			{
				input.Add(line);
			}

			var regex = new Regex(@"^(?<name>.*): capacity (?<capacity>[\-]?[0-9]+), durability (?<durability>[\-]?[0-9]+), flavor (?<flavor>[\-]?[0-9]+), texture (?<texture>[\-]?[0-9]+), calories (?<calories>[\-]?[0-9]+)$");

			var ingredients = new List<Ingredient>();

			foreach (var c in input)
			{
				var m = regex.Matches(c)[0];

				var name = m.Groups["name"].Value;
				var capacity = long.Parse(m.Groups["capacity"].Value);
				var durability = long.Parse(m.Groups["durability"].Value);
				var flavor = long.Parse(m.Groups["flavor"].Value);
				var texture = long.Parse(m.Groups["texture"].Value);
				var calories = long.Parse(m.Groups["calories"].Value);

				Console.WriteLine($"{name}, {capacity}, {durability}, {flavor}, {texture}, {calories}");
				ingredients.Add(new Ingredient
				{
					Name = name,
					Capacity = capacity,
					Durability = durability,
					Flavor = flavor,
					Texture = texture,
					Calories = calories
				});

			}
			var numbers = Enumerable.Range(0, 100).ToList();



			var combinations = numbers.Combinations(ingredients.Count).Where(a => a.Sum() == 100).ToList();

			long max1 = 0;
			long max2 = 0;

			ulong j = 0;

			Console.WriteLine($"Combination count: {combinations.Count}");


			foreach (var c in combinations)
			{
				var a = c.ToArray();
				long capacity = 0;
				long durability = 0;
				long flavor = 0;
				long texture = 0;
				long calories = 0;

				for (var i = 0; i < ingredients.Count; i++)
				{
					capacity += ingredients[i].Capacity * a[i];
					durability += ingredients[i].Durability * a[i];
					flavor += ingredients[i].Flavor * a[i];
					texture += ingredients[i].Texture * a[i];
					calories += ingredients[i].Calories * a[i];
				}

				capacity = Math.Max(0, capacity);
				durability = Math.Max(0, durability);
				flavor = Math.Max(0, flavor);
				texture = Math.Max(0, texture);



				long v = capacity * durability * flavor * texture;
				
				max1 = Math.Max(v, max1);

				if (calories == 500)
				{
					max2 = Math.Max(v, max2);
				}

				if (j % 10000 == 0)
				{
					Console.WriteLine($"{string.Join(",", a)} : {capacity},{durability},{flavor},{texture}");
					Console.WriteLine($"{j} : {max1} : {max2}");
				}

				j++;
			}

			Console.WriteLine("Max Part 1: " + max1);
			Console.WriteLine("Max Part 2: " + max2);

			Console.ReadLine();
		}
	}

	public static class Extensions
	{
		public static IEnumerable<IEnumerable<T>> Combinations<T>(this List<T> elements, int k)
		{
			return k == 0 ? new[] { new T[0] } :
			  elements.SelectMany((e, i) =>
				elements.Combinations(k - 1).Select(c => (new[] { e }).Concat(c)));
		}
	}

	public class Ingredient
	{
		public string Name { get; set; }
		public long Capacity { get; set; }
		public long Durability { get; set; }
		public long Flavor { get; set; }
		public long Texture { get; set; }
		public long Calories { get; set; }
	}
}