AdventOfCode/AdventOfCode.Solutions/2024/Day 11/Day11.cs

using AdventOfCode.Core.Shared.IO;

namespace AdventOfCode.Solutions._2024
{
    public class Day11 : IChallange
    {
        public int Year => 2024;

        public int Day => 11;

        private readonly IInputReader _inputReader;

        public Day11(IInputReader inputReader)
        {
            _inputReader = inputReader;
            _inputReader.SetInput(this);
            //_inputReader.SetSampleInput(true);
        }

        // 55312
        // 220999
        public async Task<string> GetSolutionPart1()
        {
            string input = await _inputReader.ReadAsString();
            List<long> stones = input.Split(' ').Select(long.Parse).ToList();
            //Print(stones);

            for (int i = 0; i < 25; i++)
            {
                stones = ApplyRules(stones);
                Console.WriteLine($"{i}: {stones.Count}");
                //Print(stones);
            }

            return stones.Count.ToString();
        }

        // 6
        // 
        public async Task<string> GetSolutionPart2()
        {
            string input = await _inputReader.ReadAsString();
            List<long> stones = input.Split(' ').Select(long.Parse).ToList();
            long total = 0;
            //Print(stones);
            for (int i = 0; i < stones.Count; i++)
            {
                List<long> stone = [stones[i]];
                for (int y = 0; y < 75; y++)
                {
                    stone = ApplyRules(stone);
                    //Print(stones);
                }
                total += stone.Count;
            }

            return total.ToString();
        }

        private List<long> ApplyRules(List<long> stones)
        {
            List<long> stonesResult = [];

            for (int i = 0; i < stones.Count; i++)
            {
                var stone = stones[i];
                string stringStone = stone.ToString();

                // check length
                if (stone == 0)
                {
                    stonesResult.Add(1);
                }
                else if (stringStone.Length % 2 == 0)
                {
                    stonesResult.Add(long.Parse(stringStone[..(stringStone.Length / 2)]));
                    stonesResult.Add(long.Parse(stringStone.Substring(stringStone.Length / 2, stringStone.Length / 2)));
                }
                else
                {
                    stonesResult.Add(stone * 2024);
                }
            }

            return stonesResult;
        }

        private static void Print(List<string> stones) 
        {
            Console.WriteLine($"Stones: {string.Join(", ", stones)}");
        }
    }
}