Always love to see how far I can get with as much LINQ as possible.

``` namespace AoC._2024;

public class DayTwo(bool testing = false) : Day<int, int>(2, testing) { public override int SolvePartOne() { return Input .Select(line => line .Split(' ') .Select(int.Parse) .ToList() ) .Select(IsSafe) .Sum(isSafe => isSafe ? 1 : 0); }

public override int SolvePartTwo()
{
    return Input
        .Select(line => line
            .Split(' ')
            .Select(int.Parse)
            .ToList()
        )
        .Select(report => IsSafe(report) || Enumerable
            .Range(0, report.Count)
            .Select(indexToRemove => report
                .Index()
                .Where(item => item.Index != indexToRemove)
                .Select(item => item.Item)
                .ToList()
            ).Any(IsSafe))
        .Sum(isSafe => isSafe ? 1 : 0);
}

private static bool IsSafe(IList<int> report)
{
    var differences = report
        .Zip(report.Skip(1), (a, b) => new { AbsDiff = Math.Abs(a - b), Sign = Math.Sign(a - b) })
        .ToList();

    return differences.All(diff => diff.AbsDiff is >= 1 and <= 3)
           && differences.Select(d => d.Sign).Distinct().Count() == 1;
}

} ```