AdventOfCode/AdventOfCode.Solutions/2024/Day 02/Day02.cs

using AdventOfCode.Core.Shared.IO;
using System;
using System.Reflection;

namespace AdventOfCode.Solutions._2024
{
    public class Day02 : IChallange
    {
        public int Year => 2024;
        public int Day => 2;

        private readonly IInputReader _inputReader;

        public Day02(IInputReader inputReader)
        {
            _inputReader = inputReader;
            _inputReader.SetInput(this);
        }

        //2
        //230
        public async Task<string> GetSolutionPart1() 
            => (await _inputReader.ReadAsArrayString())
                .Select(ParselineToReports)
                .Where(reports => AreReportsSave(reports, false))
                .Count()
                .ToString();

        //4
        //301
        public async Task<string> GetSolutionPart2() => (await _inputReader.ReadAsArrayString())
                .Select(ParselineToReports)
                .Where(reports => AreReportsSave(reports, true))
                .Count()
                .ToString();

        private static bool AreReportsSave(int[] reports, bool tolarance = false)
        {
            bool isIncrease = reports[1] < reports[0];
            for (int index = 1; index < reports.Length; index++)
            {
                int trueDiff = reports[index - 1] - reports[index];
                int diff = Math.Abs(trueDiff);
                if (diff < 1 || diff > 3)
                {
                    return tolarance && HasSafeCombo(reports);
                }

                if ((isIncrease && trueDiff < 0) || (!isIncrease && trueDiff > 0))
                {
                    return tolarance && HasSafeCombo(reports);
                }
            }

            return true;
        }

        private static bool HasSafeCombo(int[] reports)
            => reports.Select((_, i) => SkipReport(reports, i)).Any(reports => AreReportsSave(reports));

        private static int[] SkipReport(int[] reports, int index) => reports.Where((_, i) => i != index).ToArray();
        private static int[] ParselineToReports(string line) => line.Split(' ').Select(int.Parse).ToArray();
    }
}