day 3

2023-12-03 12:59:53 -05:00
parent 26d876e178
commit 1261f35520
5 changed files with 429 additions and 0 deletions
--- a/AdventOfCode/Problems/AOC2023/Day3/GearRatios.cs
+++ b/AdventOfCode/Problems/AOC2023/Day3/GearRatios.cs
@@ -0,0 +1,136 @@
+using AdventOfCode.Runner.Attributes;
+
+namespace AdventOfCode.Problems.AOC2023.Day3;
+
+[ProblemInfo(2023, 3, "Gear Ratios")]
+internal class GearRatios : Problem<int, int>
+{
+	private string[] _data = [];
+	private int _width;
+	private int _height;
+
+	public override void LoadInput()
+	{
+		_data = ReadInputLines();
+		_width = _data[0].Length - 1;
+		_height = _data.Length - 1;
+	}
+
+	public override void CalculatePart1()
+	{
+		var partNumbers = new List<int>();
+
+		for (int y = 0; y < _height; y++)
+		{
+			for (int x = 0; x <= _width; x++)
+			{
+				var cell = _data[y][x];
+				switch (cell - '0')
+				{
+					case '.' - '0':
+						continue;
+					case < 0 or > 9:
+						FindNumbers(x, y, ref partNumbers);
+						break;
+				}
+			}
+		}
+		Part1 = partNumbers.Sum();
+	}
+
+	public void FindNumbers(int x, int y, ref List<int> results)
+	{
+		var seen = new HashSet<(int x, int y)>();
+
+		var n = GetNeighborPoints(x, y);
+		foreach (var (xN, yN) in n)
+		{
+			var c = _data[yN][xN] - '0';
+			if (c >= 0)
+			{
+				var num = GetNumber(xN, yN, out var idx);
+
+				if (seen.Contains(idx))
+					continue;
+				seen.Add(idx);
+				results.Add(num);
+			}
+		}
+	}
+
+	public int GetNumber(int x, int y, out (int iX, int iY) index)
+	{
+		var row = _data[y];
+
+		var numStart = 0;
+		var numEnd = _width + 1;
+		for (int i = x; i >= 0; i--)
+		{
+			switch (row[i] - '0')
+			{
+				case < 0 or > 9:
+					numStart = i + 1;
+					goto leftDone;
+			}
+		}
+	leftDone:
+		for (int i = x; i <= _width; i++)
+		{
+			switch (row[i] - '0')
+			{
+				case < 0 or > 9:
+					numEnd = i;
+					goto done;
+			}
+		}
+	done:
+		index = (numStart, y);
+		return int.Parse(row[numStart..numEnd]);
+	}
+
+	public List<(int x, int y)> GetNeighborPoints(int x, int y)
+	{
+		var points = new List<(int x, int y)>();
+		if (x > 0)
+			points.Add((x - 1, y));
+		if (x < _width)
+			points.Add((x + 1, y));
+		if (y > 0)
+			points.Add((x, y - 1));
+		if (y < _height)
+			points.Add((x, y + 1));
+		if (x > 0 && y > 0)
+			points.Add((x - 1, y - 1));
+		if (x > 0 && y < _height)
+			points.Add((x - 1, y + 1));
+		if (x < _width && y < _height)
+			points.Add((x + 1, y + 1));
+		if (x < _width && y > 0)
+			points.Add((x + 1, y - 1));
+
+		return points;
+	}
+
+	public override void CalculatePart2()
+	{
+		var ratios = new List<int>();
+		var curNums = new List<int>();
+		for (int y = 0; y < _height; y++)
+		{
+			for (int x = 0; x <= _width; x++)
+			{
+				var cell = _data[y][x];
+				switch (cell)
+				{
+					case '*':
+						curNums.Clear();
+						FindNumbers(x, y, ref curNums);
+						if(curNums.Count == 2)
+							ratios.Add(curNums[0] * curNums[1]);
+						break;
+				}
+			}
+		}
+		Part2 = ratios.Sum();
+	}
+}