feat(2023-03): Finish day 3

AdventOfCode/AOC.Tests/Y2023/Day03.cs

@@ -1,23 +1,23 @@
-using System.Reflection;
+namespace AOC.Tests.Y2023;
 
-namespace AOC.Tests.Y2023
+[TestFixture]
+[Parallelizable(ParallelScope.All)]
+public class Day03
 {
-    [TestFixture, Parallelizable(ParallelScope.All)]
-    public class Day03
-    {
-        protected string GetThisClassName() { return this.GetType().Name; }
-        private string[] realData;
-
     [SetUp]
     public void Setup()
     {
-            realData = File.ReadAllLines(Path.Combine(TestContext.CurrentContext.TestDirectory, "Y2023", "Data", $"{GetThisClassName()}.dat"));
+        realData = File.ReadAllLines(Path.Combine(TestContext.CurrentContext.TestDirectory, "Y2023", "Data",
+            $"{GetThisClassName()}.dat"));
     }
 
+    protected string GetThisClassName() { return GetType().Name; }
+    private string[] realData;
+
     private bool CheckSurroundingCellsForSymbols(char[,] grid, List<(int, int)> coords, bool isTesting = false)
     {
         char[,] grid2 = new char[grid.GetLength(0), grid.GetLength(1)];
-            foreach (var coord in coords)
+        foreach ((int, int) coord in coords)
         {
             int x = coord.Item1;
             int y = coord.Item2;
@@ -63,9 +63,11 @@ namespace AOC.Tests.Y2023
                 {
                     line += grid2[i, j] != '\u0000' ? grid2[i, j] : '.';
                 }
+
                 Console.WriteLine(line);
             }
         }
+
         return false;
     }
 
@@ -91,7 +93,7 @@ namespace AOC.Tests.Y2023
         // Iterate over each cell in the grid.
         for (int i = 0; i < rows; i++)
         {
-                Console.WriteLine($"Line {i+1}");
+            Console.WriteLine($"Line {i + 1}");
             for (int j = 0; j < cols; j++)
             {
                 List<(int, int)> numberCoords = new();
@@ -123,7 +125,7 @@ namespace AOC.Tests.Y2023
                         // Check the eight surrounding cells of each digit in the number.
                         if (numberCoords.Count > 0)
                         {
-                                bool isValidPartNumber = CheckSurroundingCellsForSymbols(grid, numberCoords, false);
+                            bool isValidPartNumber = CheckSurroundingCellsForSymbols(grid, numberCoords);
                             // If any of the surrounding cells contain a symbol, add the number to a list.
                             if (isValidPartNumber)
                             {
@@ -140,15 +142,89 @@ namespace AOC.Tests.Y2023
         return numbers;
     }
 
-        public bool CheckSurroundingCellsForNumbers(char[,] grid, List<(int, int)> coords, bool isTesting = false)
+    private int CountNumbers(List<(int, int)> numberCoords)
     {
-            foreach (var gearCoord in coords)
+        // Group coordinates by the X-axis and sort each group by the Y-axis
+        IEnumerable<IOrderedEnumerable<(int, int)>> groupedCoords = numberCoords.GroupBy(coord => coord.Item1)
+            .Select(group => group.OrderBy(coord => coord.Item2));
+
+        int numberCount = 0;
+        foreach (IOrderedEnumerable<(int, int)> group in groupedCoords)
+        {
+            int lastY = int.MinValue;
+            foreach ((int, int) coord in group)
+            {
+                // If there is a gap in the Y-axis, increment the number count
+                if (coord.Item2 - lastY > 1)
+                {
+                    numberCount++;
+                }
+
+                lastY = coord.Item2;
+            }
+        }
+
+        return numberCount;
+    }
+
+    private List<int> ExtractNumbers(List<(int, int)> numberCoords, char[,] grid)
+    {
+        // Initialize a list to hold the extracted numbers
+        List<int> numbers = new();
+
+        // Sort the coordinates by Y-axis (Item2) then by X-axis (Item1)
+        List<(int, int)> sortedCoords =
+            numberCoords.OrderBy(coord => coord.Item2).ThenBy(coord => coord.Item1).ToList();
+
+        // Create a HashSet to keep track of processed coordinates
+        HashSet<(int, int)> processedCoords = new();
+
+        foreach ((int x, int y) in sortedCoords)
+        {
+            // Skip this coordinate if it has already been processed
+            if (processedCoords.Contains((x, y)))
+            {
+                continue;
+            }
+
+            // Start from the current coordinate and scan to the left until a non-digit is found or it reaches the beginning of the row
+            int startX = x;
+            while (startX > 0 && char.IsDigit(grid[startX - 1, y]))
+            {
+                startX--;
+            }
+
+            // Build the number by scanning to the right from the startX position
+            string currentNumberStr = "";
+            int currentX = startX;
+            while (currentX < grid.GetLength(0) && char.IsDigit(grid[currentX, y]))
+            {
+                currentNumberStr += grid[currentX, y];
+                // Mark the coordinate as processed
+                processedCoords.Add((currentX, y));
+                currentX++;
+            }
+
+            // If a number is formed, add it to the list
+            if (currentNumberStr.Length > 0)
+            {
+                numbers.Add(int.Parse(currentNumberStr));
+            }
+        }
+
+        // Return the list of extracted numbers
+        return numbers;
+    }
+
+
+    private int GetGearRatioFromExactlyTwoNumbersInSurroundingCells(char[,] grid, (int, int) gearCoord)
     {
         List<(int, int)> numberCoords = new();
         int x = gearCoord.Item1;
         int y = gearCoord.Item2;
+        int gearRatio = 0;
 
-                // Check the eight surrounding cells of each digit in the number.
+        // Check the eight surrounding cells of the gear 
         for (int i = x - 1; i <= x + 1; i++)
         {
             for (int j = y - 1; j <= y + 1; j++)
@@ -163,46 +239,59 @@ namespace AOC.Tests.Y2023
             }
         }
 
-                if (numberCoords.Count == 2)
+        // Consider each set of cells in the same x axis with a digit to their immediate right as a single number
+        foreach ((int, int) numberCoord in numberCoords)
         {
-                    int number1 = int.Parse(grid[numberCoords[0].Item1, numberCoords[0].Item2].ToString());
+            Console.WriteLine($"{numberCoord.Item1},{numberCoord.Item2}");
-                    int number2 = int.Parse(grid[numberCoords[1].Item1, numberCoords[1].Item2].ToString());
-                    int gearRatio = number1 * number2;
-                    // gearRatios.Add(gearRatio);
         }
+
+        Console.WriteLine("---");
+
+        List<int> numbers = ExtractNumbers(numberCoords, grid);
+
+        foreach (int number in numbers)
+        {
+            Console.WriteLine($"Number: {number}");
         }
-            return false;
+
+        Console.WriteLine("===");
+
+        if (numbers.Count == 2)
+        {
+            // If there are exactly two numbers around the gear, generate the gear ratio
+            gearRatio = numbers[0] * numbers[1];
+            Console.WriteLine($"{numbers[0]} * {numbers[1]} = {gearRatio}");
+        }
+
+        return gearRatio;
     }
 
 
-        private List<int> GetAllGearRatios(string[] lines)
+    private int GetSumOfAllGearRatios(string[] lines)
     {
         // Create a 2D array to represent the grid.
-            int rows = lines.Length;
         int cols = lines[0].Length;
-            char[,] grid = new char[rows, cols];
+        int rows = lines.Length;
+        char[,] grid = new char[cols, rows];
 
         // Populate the grid
-            for (int i = 0; i < rows; i++)
+        for (int j = 0; j < rows; j++)
         {
-                string line = lines[i];
+            string line = lines[j];
-                for (int j = 0; j < cols; j++)
+            for (int i = 0; i < cols; i++)
             {
-                    grid[i, j] = line[j];
+                grid[i, j] = line[i];
             }
         }
 
-            List<int> gearRatios = new();
         List<(int, int)> gearCoords = new();
 
         // Iterate over each cell in the grid to find all gears
-            for (int i = 0; i < rows; i++)
+        for (int i = 0; i < cols; i++)
         {
-                Console.WriteLine($"Line {i+1}");
+            // Console.WriteLine($"Line {i + 1}");
-                for (int j = 0; j < cols; j++)
+            for (int j = 0; j < rows; j++)
             {
-                    
-
                 if (grid[i, j] == '*')
                 {
                     gearCoords.Add((i, j));
@@ -210,10 +299,13 @@ namespace AOC.Tests.Y2023
             }
         }
 
-            // Now find all instances where exactly two numbers are adjacent to a gear
+        int gearRatios = 0;
+        // Now find all instances where exactly two numbers are adjacent to a gear and sum their gear ratios
+        foreach ((int, int) gear in gearCoords)
+        {
+            gearRatios += GetGearRatioFromExactlyTwoNumbersInSurroundingCells(grid, gear);
+        }
 
-
-            // Return the list of numbers.
         return gearRatios;
     }
 
@@ -247,34 +339,34 @@ namespace AOC.Tests.Y2023
 
         List<(int, int)> coords = new()
         {
-                (0,0),
+            (0, 0),
-                (0,1),
+            (0, 1),
-                (0,2),
+            (0, 2),
-                (0,5),
+            (0, 5),
-                (0,6),
+            (0, 6),
-                (0,7),
+            (0, 7),
-                (2,2),
+            (2, 2),
-                (2,3),
+            (2, 3),
-                (2,6),
+            (2, 6),
-                (2,7),
+            (2, 7),
-                (2,8),
+            (2, 8),
-                (4,0),
+            (4, 0),
-                (4,1),
+            (4, 1),
-                (4,2),
+            (4, 2),
-                (5,7),
+            (5, 7),
-                (5,8),
+            (5, 8),
-                (6,2),
+            (6, 2),
-                (6,3),
+            (6, 3),
-                (6,4),
+            (6, 4),
-                (7,6),
+            (7, 6),
-                (7,7),
+            (7, 7),
-                (7,8),
+            (7, 8),
-                (9,1),
+            (9, 1),
-                (9,2),
+            (9, 2),
-                (9,3),
+            (9, 3),
-                (9,5),
+            (9, 5),
-                (9,6),
+            (9, 6),
-                (9,7),
+            (9, 7)
         };
 
         CheckSurroundingCellsForSymbols(grid, coords, true);
@@ -332,10 +424,10 @@ namespace AOC.Tests.Y2023
         string[] lines = input != null ? input.Split("\n") : realData;
 
         // A gear is any * symbol that is adjacent to exactly two part numbers. Its gear ratio is the result of multiplying those two numbers together.
-            List<int> gearRatios = GetAllGearRatios(lines);
+        int gearRatiosSum = GetSumOfAllGearRatios(lines);
 
         // The result is the sum of all the gear ratios
-            int result = gearRatios.Sum();
+        int result = gearRatiosSum;
 
         if (expected != null)
         {
@@ -344,5 +436,4 @@ namespace AOC.Tests.Y2023
 
         Console.WriteLine($"Part 2: {result}");
     }
-    }
 }