Day 8

AdventOfCode/AdventOfCode.csproj

@@ -55,6 +55,8 @@
 	<None Remove="problems\aoc2023\day7\input.txt" />
 	<None Remove="problems\aoc2023\day7\sample.txt" />
 	<None Remove="problems\aoc2023\day7\sara.txt" />
+	<None Remove="problems\aoc2023\day8\input.txt" />
+	<None Remove="problems\aoc2023\day8\sample.txt" />
   </ItemGroup>
 
 

AdventOfCode/Problems/AOC2023/Day8/HauntedWasteland.cs

@@ -0,0 +1,74 @@
+using AdventOfCode.Runner.Attributes;
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace AdventOfCode.Problems.AOC2023.Day8;
+
+[ProblemInfo(2023, 8, "Haunted Wasteland")]
+internal class HauntedWasteland : Problem<int, long>
+{
+	private string _path = string.Empty;
+	private Dictionary<string, (string left, string right)> _nodes = [];
+
+	public override void LoadInput()
+	{
+		var data = ReadInputLines();
+		_path = data[0];
+
+		for (int i = 2; i < data.Length; i++)
+		{
+			var curLine = data[i].Split('=');
+			var node = curLine[0].TrimEnd();
+			var branches = curLine[1][2..^1].Split(", ");
+			_nodes.Add(node, (branches[0], branches[1]));
+		}
+	}
+
+	public override void CalculatePart1()
+	{
+		var curPos = "AAA";
+		var i = 0;
+		var steps = 0;
+		do
+		{
+			curPos = _path[i] switch
+			{
+				'L' => _nodes[curPos].left,
+				'R' => _nodes[curPos].right,
+				_ => throw new Exception("Something went horribly wrong")
+			};
+			i = (i + 1) % _path.Length;
+			steps++;
+		} while (curPos != "ZZZ");
+		Part1 = steps;
+	}
+
+	public override void CalculatePart2()
+	{
+		var curPos = _nodes.Keys.Where(n => n[^1] == 'A').ToArray();
+		var len = new long[curPos.Length];
+		var i = 0;
+		do
+		{
+			for (int j = 0; j < curPos.Length; j++)
+			{
+				if (curPos[j][^1] == 'Z')
+					continue;
+				len[j]++;
+				curPos[j] = _path[i] switch
+				{
+					'L' => _nodes[curPos[j]].left,
+					'R' => _nodes[curPos[j]].right,
+					_ => throw new Exception("Something went horribly wrong")
+				};
+			}
+			i = (i + 1) % _path.Length;
+		} while (curPos.Any(n => n[^1] != 'Z'));
+
+		Part2 = len.LCM();
+	}
+}

AdventOfCode/Runner/Extensions.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Numerics;
 using System.Text;
 using System.Threading.Tasks;
 
@@ -15,4 +16,15 @@ public static class Extensions
 		}
 		return values;
 	}
+
+	public static T LCM<T>(this IEnumerable<T> values) where T : INumber<T>
+	{
+		var a = values.First();
+		values = values.Skip(1);
+		foreach (var item in values)
+		{
+			a = a.LCM(item);
+		}
+		return a;
+	}
 }

AdventOfCode/Runner/ExtraMath.cs

@@ -0,0 +1,26 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Numerics;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace AdventOfCode.Runner;
+public static class ExtraMath
+{
+	public static T GCF<T>(this T a, T b) where T : INumber<T>
+	{
+		while (!b.Equals(T.Zero))
+		{
+			var t = b;
+			b = a % b;
+			a = t;
+		}
+		return a;
+	}
+
+	public static T LCM<T>(this T a, T b) where T: INumber<T>
+	{
+		return (a / GCF(a, b)) * b;
+	}
+}