From f18ebfcb217eda0910d53e1264ded66921e89302 Mon Sep 17 00:00:00 2001
From: Amatsugu <khamraj@kaisei.app>
Date: Wed, 4 Dec 2024 20:45:09 -0500
Subject: [PATCH] day 4

---
 .../Problems/AOC2024/Day4/CeresSearch.cs      | 130 ++++++++++++++++++
 AdventOfCode/Program.cs                       |   1 +
 2 files changed, 131 insertions(+)
 create mode 100644 AdventOfCode/Problems/AOC2024/Day4/CeresSearch.cs

diff --git a/AdventOfCode/Problems/AOC2024/Day4/CeresSearch.cs b/AdventOfCode/Problems/AOC2024/Day4/CeresSearch.cs
new file mode 100644
index 0000000..90d61be
--- /dev/null
+++ b/AdventOfCode/Problems/AOC2024/Day4/CeresSearch.cs
@@ -0,0 +1,130 @@
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+using Pos = (int x, int y);
+
+namespace AdventOfCode.Problems.AOC2024.Day4;
+[ProblemInfo(2024, 4, "Ceres Search")]
+internal class CeresSearch : Problem<int, int>
+{
+
+	private string[] _data = [];
+	private static Pos[] dirs = [
+		(-1, 0),	//Left
+		(-1, -1),	//Top Left
+		(0, -1),	//Top
+		(1, -1),	//Top Right
+		(1, 0),		//Right
+		(1, 1),		//Bottom Right
+		(0, 1),		//Bottom
+		(-1, 1),	//Bottom Left
+		];
+
+	private static Pos[] xdirs = [
+		(-1, -1),	//Top Left
+		(1, -1),	//Top Right
+		(1, 1),		//Bottom Right
+		(-1, 1),	//Bottom Left
+		];
+
+	public override void CalculatePart1()
+	{
+		Part1 = FindWord(_data, "XMAS");
+	}
+
+	public override void CalculatePart2()
+	{
+		Part2 = FindXWord(_data, "MAS");
+	}
+	public override void LoadInput()
+	{
+		_data = ReadInputLines("input.txt");
+	}
+
+	private static int FindXWord(string[] data, string target)
+	{
+		var matches = 0;
+		var pivot = target.Length / 2;
+		var tgt = target[pivot];
+		var branchA = string.Join("", target[..(pivot+1)].Reverse());
+		var branchB = target[pivot..];
+		for (int y = 0; y < data.Length; y++)
+		{
+			var row = data[y];
+			for (int x = 0; x < row.Length; x++)
+			{
+				var c = row[x];
+				if (c == tgt)
+				{
+					for (int i = 0; i < xdirs.Length; i++)
+					{
+						Pos dir = xdirs[i];
+						Pos opposingDir = xdirs[(i + 2) % xdirs.Length];
+
+						if (CheckWord(data, (x, y), dir, branchA, 1, [c]) && CheckWord(data, (x,y), opposingDir, branchB, 1, [c]))
+						{
+							Pos dir2 = xdirs[(i+1) % xdirs.Length];
+							Pos opposingDir2 = xdirs[(i + 3) % xdirs.Length];
+							if (CheckWord(data, (x, y), dir2, branchA, 1, [c]) && CheckWord(data, (x, y), opposingDir2, branchB, 1, [c]))
+								matches++;
+						}
+					}	
+				}
+			}
+		}
+		return matches;
+	}
+
+	private static int FindWord(string[] data, string target)
+	{
+		var matches = 0;
+		var tgt = target[0];
+		for (int y = 0; y < data.Length; y++)
+		{
+			var row = data[y];
+			for (int x = 0; x < row.Length; x++)
+			{
+				var c = row[x];
+				if(c == tgt)
+				{
+					foreach (var dir in dirs)
+					{
+						if(CheckWord(data, (x, y), dir, target, 1, [c]))
+							matches++;
+					}
+				}
+			}
+		}
+		return matches;
+	}
+
+	private static bool CheckWord(string[] data, Pos pos, Pos dir, string target, int targetPos, List<char>? acc = null)
+	{
+		if (acc == null)
+			acc = [];
+		Pos curPos = (pos.x + dir.x, pos.y + dir.y);
+
+
+		if(curPos.y < 0 || curPos.y >= data.Length)
+			return false;
+		if (curPos.x < 0 || curPos.x >= data[0].Length)
+			return false;
+
+		var c = data[curPos.y][curPos.x];
+		if(c == target[targetPos])
+		{
+			acc.Add(c);
+			if (targetPos == target.Length - 1)
+				return true;
+			return CheckWord(data, curPos, dir, target, targetPos + 1, acc);
+		}
+		return false;
+	}
+
+
+	
+}
diff --git a/AdventOfCode/Program.cs b/AdventOfCode/Program.cs
index 61d4f82..4786316 100644
--- a/AdventOfCode/Program.cs
+++ b/AdventOfCode/Program.cs
@@ -1,4 +1,5 @@
 global using AdventOfCode.Runner;
+global using AdventOfCode.Runner.Attributes;
 
 var runner = new AOCRunner();
 runner.RenderInteractiveMenu();