2023 Day03 Refactored

smabuk · Dec 3, 2023 · 3cbb949 · 3cbb949
1 parent 9a50d64
commit 3cbb949
Showing 1 changed file with 56 additions and 50 deletions.
diff --git a/Solutions/2023/Day03.cs b/Solutions/2023/Day03.cs
@@ -1,4 +1,4 @@
-using System.Linq;
+using PartNoAndAPosition = (int PartNo, Smab.Helpers.Point Position);
 
 namespace AdventOfCode.Solutions._2023;
 
@@ -12,64 +12,18 @@ public sealed partial class Day03 {
 	public static string Part1(string[] input, params object[]? _) => Solution1(input).ToString();
 	public static string Part2(string[] input, params object[]? _) => Solution2(input).ToString();
 
-	private static int Solution1(string[] input) {
-		List<int> partNos = [];
-
-		char[,] engine = string.Join("", input).To2dArray<char>(input[0].Length);
-		int maxX = input[0].Length - 1;
-		int maxY = input.Length - 1;
-		for (int row = 0; row < input.Length; row++) {
-			string engineLine = input[row].Replace('.', ' ');
-			MatchCollection possibleParts = Regex.Matches(engineLine, @"(?<number>\d+)");
-			foreach (Match number in possibleParts) {
-				bool foundPart = false;
-				for (int y = Math.Max(row - 1, 0); y <= Math.Min(row + 1, maxY); y++) {
-					for (int x = Math.Max(number.Index - 1, 0); x < Math.Min(number.Index + number.Length + 1, maxX); x++) {
-						char cell = engine[x, y];
-						if (!char.IsDigit(cell) && cell is not '.') {
-							partNos.Add(number.Value.AsInt());
-							foundPart = true;
-							break;
-						}
-					}
-					if (foundPart) {
-						break;
-					}
-				}
-			}
-		}
-
-		return partNos.Sum();
-	}
+	private static int Solution1(string[] input) => FindPartNosAndGears(input, 1).Select(p => p.PartNo).Sum();
 
 	private static int Solution2(string[] input) {
-		List<(int PartNo, Point Position)> possibleGears = [];
-
-		char[,] engine = string.Join("", input).To2dArray<char>(input[0].Length);
-		int maxX = input[0].Length - 1;
-		int maxY = input.Length - 1;
-		for (int row = 0; row < input.Length; row++) {
-			string engineLine = input[row].Replace('.', ' ');
-			MatchCollection possibleParts = Regex.Matches(engineLine, @"(?<number>\d+)");
-			foreach (Match number in possibleParts) {
-				for (int y = Math.Max(row - 1, 0); y <= Math.Min(row + 1, maxY); y++) {
-					for (int x = Math.Max(number.Index - 1, 0); x < Math.Min(number.Index + number.Length + 1, maxX); x++) {
-						char cell = engine[x, y];
-						if (cell is '*') {
-							possibleGears.Add((number.Value.AsInt(), new(x, y)));
-						}
-					}
-				}
-			}
-		}
+		List<PartNoAndAPosition> possibleGears = FindPartNosAndGears(input, 2);
 
 		IEnumerable<Point> gearPositions = possibleGears
 			.GroupBy(p => p.Position)
 			.Where(p => p.Count() == 2)
 			.Select(g => g.Key);
 
 		int sumOfGearRatios = 0;
-		foreach (var position in gearPositions) {
+		foreach (Point position in gearPositions) {
 			sumOfGearRatios += possibleGears
 				.Where(g => g.Position == position)
 				.Select(g => g.PartNo)
@@ -78,4 +32,56 @@ private static int Solution2(string[] input) {
 
 		return sumOfGearRatios;
 	}
+
+	private static List<PartNoAndAPosition> FindPartNosAndGears(string[] input, int solutionPartNo)
+	{
+		const char GEAR  = '*';
+		const char SPACE = '.';
+
+		char[,] engineSchematic = string.Join("", input).To2dArray(input[0].Length);
+		int maxX = input[0].Length - 1;
+		int maxY = input.Length - 1;
+
+		List<PartNoAndAPosition> list = [];
+
+		for (int row = 0; row < input.Length; row++) {
+			foreach (Match number in NumberRegex().Matches(input[row])) {
+				SearchAdjacent(row, number);
+			}
+		}
+
+		return list;
+
+		void SearchAdjacent(int row, Match number)
+		{
+			int lowerY = Math.Max(row - 1, 0);
+			int upperY = Math.Min(row + 1, maxY);
+			int lowerX = Math.Max(number.Index - 1, 0);
+			int upperX = Math.Min(number.Index + number.Length + 1, maxX);
+			int skip   = Math.Max(number.Length - 2, 1); // Can skip self
+			bool foundPart = false;
+			for (int y = lowerY; y <= upperY; y++) {
+				for (int x = lowerX; x < upperX; x += (y == row ? skip : 1)) {
+					char cellValue = engineSchematic[x, y];
+					if (solutionPartNo == 1) {
+						if (IsSymbol(cellValue)) {
+							list.Add((number.Value.AsInt(), new(number.Index, row)));
+							foundPart = true;
+							break;
+						}
+					} else if (cellValue is GEAR) { // Part2
+						list.Add((number.Value.AsInt(), new(x, y)));
+					}
+				}
+				if (foundPart) {
+					break;
+				}
+			}
+		}
+
+		bool IsSymbol(char cell) => !(char.IsDigit(cell) || cell is SPACE);
+	}
+
+	[GeneratedRegex(@"\d+")]
+	private static partial Regex NumberRegex();
 }