Merge pull request #33 from MartinZikmund/feature/aoc2025-day7

Author: MartinZikmund

src/AdventOfCode.Puzzles/2025/07/Part1/AoC2025Day7Part1.cs

@@ -0,0 +1,64 @@
+namespace AdventOfCode.Puzzles._2025._07.Part1;
+
+public class AoC2025Day7Part1 : IPuzzleSolution
+{
+    private int _height;
+    private int _width;
+    private char[,] _map;
+    private HashSet<Point> _splitters;
+
+    public async Task<string> SolveAsync(StreamReader inputReader)
+    {
+        var lines = await inputReader.ReadAllLinesAsync();
+        _height = lines.Count;
+        _width = lines[0].Length;
+        _map = new char[lines[0].Length, lines.Count];
+        Point startingPoint = new Point();
+        for (var row = 0; row < lines.Count; row++)
+        {
+            var line = lines[row];
+            for (var column = 0; column < line.Length; column++)
+            {
+                _map[column, row] = line[column];
+                if (line[column] == 'S')
+                {
+                    startingPoint = new Point(column, row);
+                }
+            }
+        }
+
+        _splitters = new HashSet<Point>();
+
+        Beam(startingPoint);
+
+        return _splitters.Count.ToString();
+    }
+
+    private void Beam(Point currentPoint)
+    {
+        if (_map[currentPoint.X, currentPoint.Y] is '.' or 'S')
+        {
+            if (currentPoint.Y + 1 < _height)
+            {
+                Beam(new(currentPoint.X, currentPoint.Y + 1));
+            }
+        }
+        else
+        {
+            if (_splitters.Contains(currentPoint))
+            {
+                return;
+            }
+
+            _splitters.Add(currentPoint);
+            if (currentPoint.X - 1 >= 0)
+            {
+                Beam(new(currentPoint.X - 1, currentPoint.Y));
+            }
+            if (currentPoint.X + 1 < _width)
+            {
+                Beam(new(currentPoint.X + 1, currentPoint.Y));
+            }
+        }
+    }
+}

src/AdventOfCode.Puzzles/2025/07/Part2/AoC2025Day7Part2.cs

@@ -0,0 +1,66 @@
+namespace AdventOfCode.Puzzles._2025._07.Part2;
+
+public class AoC2025Day7Part2 : IPuzzleSolution
+{
+    private int _height;
+    private int _width;
+    private char[,] _map;
+    private long[,] _paths;
+
+    public async Task<string> SolveAsync(StreamReader inputReader)
+    {
+        var lines = await inputReader.ReadAllLinesAsync();
+        _height = lines.Count;
+        _width = lines[0].Length;
+        _map = new char[lines[0].Length, lines.Count];
+        _paths = new long[lines[0].Length, lines.Count];
+        Point startingPoint = new Point();
+        for (var row = 0; row < lines.Count; row++)
+        {
+            var line = lines[row];
+            for (var column = 0; column < line.Length; column++)
+            {
+                _map[column, row] = line[column];
+                if (line[column] == 'S')
+                {
+                    startingPoint = new Point(column, row);
+                }
+            }
+        }
+
+        return CountPaths(startingPoint).ToString();
+    }
+
+    private long CountPaths(Point currentPoint)
+    {
+        if (_map[currentPoint.X, currentPoint.Y] is '.' or 'S')
+        {
+            if (currentPoint.Y + 1 < _height)
+            {
+                if (_paths[currentPoint.X, currentPoint.Y + 1] == 0)
+                {
+                    _paths[currentPoint.X, currentPoint.Y + 1] = CountPaths(new(currentPoint.X, currentPoint.Y + 1));
+                }
+
+                return _paths[currentPoint.X, currentPoint.Y + 1];
+            }
+            else
+            {
+                return 1;
+            }
+        }
+        else
+        {
+            if (currentPoint.X - 1 >= 0 && _paths[currentPoint.X - 1, currentPoint.Y] == 0)
+            {
+                _paths[currentPoint.X - 1, currentPoint.Y] = CountPaths(new(currentPoint.X - 1, currentPoint.Y));
+            }
+            if (currentPoint.X + 1 < _width && _paths[currentPoint.X + 1, currentPoint.Y] == 0)
+            {
+                _paths[currentPoint.X + 1, currentPoint.Y] = CountPaths(new(currentPoint.X + 1, currentPoint.Y));
+            }
+
+            return _paths[currentPoint.X - 1, currentPoint.Y] + _paths[currentPoint.X + 1, currentPoint.Y];
+        }
+    }
+}

src/AdventOfCode.Puzzles/2025/07/TestData.txt

@@ -0,0 +1,16 @@
+.......S.......
+...............
+.......^.......
+...............
+......^.^......
+...............
+.....^.^.^.....
+...............
+....^.^...^....
+...............
+...^.^...^.^...
+...............
+..^...^.....^..
+...............
+.^.^.^.^.^...^.
+...............