2024day11everyblink

public static class Day11
{
    public static long Solve1(string input) => return Solve(GetStones(input), 25);

    public static long Solve2(string input) => return Solve(GetStones(input), 75);

    private static long Solve(Dictionary<long, long> Stones, int blinks)
    {
        for (int i = 0; i < blinks; i++)
        {
            if (Stones.ContainsKey(0L))
            {
                Stones.Add(-1, Stones[0L]);
                Stones.Remove(0L);
            }
            foreach (var k in Stones.Keys.Where(kk => kk > 0L).ToArray())
            {
                if (k.ToString().Length % 2 == 0)
                {
                    long k1 = -long.Parse(k.ToString().Substring(0, k.ToString().Length / 2));
                    long k2 = -long.Parse(k.ToString().Substring(k.ToString().Length / 2, k.ToString().Length / 2));
                    Stones.Increase(k1, Stones[k]);
                    Stones.Redistribute(k2, k);
                }
                else
                {
                    Stones.Redistribute(-k * 2024L, k);
                }
            }
            Stones.Keys.Where(kk => kk < 0L).ToList().ForEach(k => Stones.Redistribute(-k, k));
        }
        return Stones.Values.Sum();
    }
    private static Dictionary<long, long> GetStones(string s)
    {
        var Stones = new Dictionary<long, long>();
        Array.ForEach(s.Split(), stone => Stones.Increase(long.Parse(stone), 1L));
        return Stones;
    }
    private static void Redistribute(this Dictionary<long, long> D, long t, long k)
    {
        D.Increase(t, D[k]);
        D.Remove(k);
    }
    private static void Increase(this Dictionary<long, long> D, long t, long v)
    {
        if (D.ContainsKey(t))
        {
            D[t] += v;
        }
        else
        {
            D.Add(t, v);
        }
    }
}