Day 11 part 1

AdventOfCode/Problems/AOC2024/Day11/PlutonianPebbles.cs

@@ -1,25 +1,94 @@
-using System;
+using Superpower.Model;
+
+using System;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
 
+using static System.Runtime.InteropServices.JavaScript.JSType;
+
 namespace AdventOfCode.Problems.AOC2024.Day11;
-//[ProblemInfo(2024, 11, "Plutonian Pebbles")]
+
-internal class PlutonianPebbles : Problem
+[ProblemInfo(2024, 11, "Plutonian Pebbles")]
+public class PlutonianPebbles : Problem<long, long>
 {
+	private List<long> _data = [];
+
 	public override void CalculatePart1()
 	{
-		throw new NotImplementedException();
+		Part1 = Run(25);
 	}
 
 	public override void CalculatePart2()
 	{
-		throw new NotImplementedException();
+		//Runs into max array length limit
+		Part2 = Run(75);
+	}
+
+	public long Run(long count)
+	{
+		var a = _data.ToList();
+		var b = new List<long>(a.Count);
+		for (long i = 0; i < count; i++)
+		{
+			foreach (var stone in a)
+				ProcessStone(stone, b);
+
+			(a, b) = (b, a);
+			b.Clear();
+		}
+		return a.Count;
+	}
+
+	public static void ProcessStone(long stone, List<long> data)
+	{
+		if (stone == 0)
+		{
+			data.Add(1);
+			return;
+		}
+		if (FastSplit(stone, out var left, out var right))
+		{
+			data.Add(left);
+			data.Add(right);
+			return;
+		}
+		data.Add(stone * 2024);
+	}
+
+	private static IEnumerable<long> Split(long stone, int len)
+	{
+		var v = stone.ToString();
+		return [long.Parse(v[..(len / 2)]), long.Parse(v[(len / 2)..])];
+	}
+
+	private static bool FastSplit(long stone, out long left, out long right)
+	{
+		var len = stone.DigitCount();
+		if (len % 2 != 0)
+		{
+			left = 0;
+			right = 0;
+			return false;
+		}
+		var l = QuickMath.FastPow10(len / 2);
+		var a = stone / l;
+
+		(left, right) = (a, stone - (a * l));
+		return true;
+
+	}
+
+	private static bool IsEvenDigits(long value, out int len)
+	{
+		var v = len = value.ToString().Length;
+		return v % 2 == 0;
 	}
 
 	public override void LoadInput()
 	{
-		throw new NotImplementedException();
+		_data = ReadInputText("input.txt").Split(' ').Select(long.Parse).ToList();
 	}
-}
+}

AdventOfCode/Utils/QuickMath.cs

@@ -0,0 +1,37 @@
+namespace AdventOfCode.Utils;
+
+public static class QuickMath
+{
+	private static readonly long[] pow10Long = [1, 10, 100, 1000, 10000, 100000, 1000000, 10000000, 100000000, 1000000000, 10000000000, 100000000000, 1000000000000, 10000000000000, 100000000000000, 1000000000000000, 10000000000000000, 100000000000000000, 1000000000000000000];
+	private static readonly int[] pow10int = [1, 10, 100, 1000, 10000, 100000, 1000000, 10000000, 100000000, 1000000000];
+
+	public static long FastPow10(long exp)
+	{
+		return pow10Long[exp];
+	}
+
+	public static int FastPow10(int exp)
+	{
+		return pow10int[exp];
+	}
+
+	private static readonly long[] longCorrectionTable= [9, 99, 999, 9999, 99999, 999999, 9999999, 99999999, 999999999, 9999999999, 99999999999, 999999999999, 9999999999999, 99999999999999, 999999999999999, 9999999999999999, 99999999999999999, 999999999999999999];
+	private static readonly int[] intCorrectionTable = [9, 99, 999, 9999, 99999, 999999, 9999999, 99999999, 999999999];
+	public static long DigitCount(this long value)
+	{
+		var l2 = 63 - long.LeadingZeroCount(value | 1);
+		var ans = ((9 * l2) >> 5);
+		if (value > longCorrectionTable[ans])
+			ans += 1;
+		return ans + 1;
+	}
+
+	public static int DigitCount(this int value)
+	{
+		var l2 = 31 - int.LeadingZeroCount(value | 1);
+		var ans = ((9 * l2) >> 5);
+		if (value > intCorrectionTable[ans])
+			ans += 1;
+		return ans + 1;
+	}
+}