AdventOfCode/AdventOfCode.Solutions/2023/Day 06/Day06.cs

using AdventOfCode.Core.Shared.IO;
using System.Text.RegularExpressions;

namespace AdventOfCode.Solutions._2023
{
    public partial class Day06 : IChallange
    {
        public int Year => 2023;
        public int Day => 6;

        private readonly IInputReader _inputReader;

        public Day06(IInputReader inputReader)
        {
            _inputReader = inputReader;
            _inputReader.SetInput(this);
        }

        public async Task<string> GetSolutionPart1()
        {
            var data = (await _inputReader.ReadAsArrayString()).Select(line => GetDigets().Matches(line)).ToArray();
            long totalValue = 1;
            for (int index = 0; index < data[0].Count; index++)
            {
                totalValue *= CalculateWays(int.Parse(data[0][index].Value), int.Parse(data[1][index].Value));
            }

            return totalValue.ToString();
        }

        public async Task<string> GetSolutionPart2()
        {
            var data = (await _inputReader.ReadAsArrayString()).Select(line => GetDigets().Matches(line.Replace(" ", string.Empty))).ToArray();
            return CalculateWays(long.Parse(data[0][0].Value), long.Parse(data[1][0].Value)).ToString();
        }

        private long CalculateWays(long raceTime, long currentDistance)
        {
            long distance,
                waysToWin = 0,
                time = raceTime;
            if (raceTime % 2 == 1)
            {
                // uneven
                time = (time + 1) / 2;
            }
            else
            {
                time /= 2;
                time++;
                waysToWin++;
            }

            do
            {
                distance = time * (raceTime - time);
                if (distance > currentDistance)
                    waysToWin += 2;

                time++;
            }
            while (distance > currentDistance);

            return waysToWin;
        }

        [GeneratedRegex(@"\d+")]
        private static partial Regex GetDigets();
    }
}