Merge pull request #16 from MartinZikmund/feature/aoc2024-day15

AoC 2024 Day 15 Solutions

src/AdventOfCode.Puzzles/2024/15/Part1/Part1.cs

@@ -0,0 +1,121 @@
+using System.Diagnostics;
+using System.Text;
+using AdventOfCode.Puzzles.Tools;
+
+namespace AdventOfCode.Puzzles._2024._15.Part1;
+
+public partial class Part1 : IPuzzleSolution
+{
+    private int _width;
+    private int _height;
+    private char[,] _map;
+    private string _instructions;
+    private Point _robotPosition;
+
+    public async Task<string> SolveAsync(StreamReader inputReader)
+    {
+        var mapLines = new List<string>();
+        while (await inputReader.ReadLineAsync() is { } line && !string.IsNullOrWhiteSpace(line))
+        {
+            mapLines.Add(line);
+        }
+
+        _width = mapLines[0].Length;
+        _height = mapLines.Count;
+        _map = new char[_width, _height];
+
+        for (int y = 0; y < _height; y++)
+        {
+            for (int x = 0; x < _width; x++)
+            {
+                _map[x, y] = mapLines[y][x];
+
+                if (_map[x, y] == '@')
+                {
+                    _robotPosition = new Point(x, y);
+                }
+            }
+        }
+
+        StringBuilder instructions = new();
+        while (await inputReader.ReadLineAsync() is { } line)
+        {
+            instructions.Append(line);
+        }
+
+        _instructions = instructions.ToString();
+
+        foreach (var instruction in _instructions)
+        {
+            MoveRobot(instruction);
+        }
+
+        var total = 0;
+        for (int y = 0; y < _height; y++)
+        {
+            for (int x = 0; x < _width; x++)
+            {
+                if (_map[x, y] == 'O')
+                {
+                    total += y * 100 + x;
+                }
+            }
+        }
+
+        return total.ToString();
+    }
+
+    private void MoveRobot(char instruction)
+    {
+        var direction = instruction switch
+        {
+            '^' => new Point(0, -1),
+            '>' => new Point(1, 0),
+            'v' => new Point(0, 1),
+            '<' => new Point(-1, 0),
+            _ => throw new InvalidOperationException()
+        };
+
+        if (CanMove(_robotPosition, direction))
+        {
+            Move(_robotPosition, direction);
+            _robotPosition += direction;
+        }        
+    }
+
+    private bool CanMove(Point position, Point direction)
+    {
+        var newPosition = position + direction;
+
+        var newTile = _map[newPosition.X, newPosition.Y];
+        if (newTile == '#')
+        {
+            return false;
+        }
+        else if (newTile == 'O')
+        {
+            return CanMove(newPosition, direction);
+        }
+        else if (newTile == '.')
+        {
+            return true;
+        }
+        else
+        {
+            throw new InvalidOperationException();
+        }
+    }
+
+    private void Move(Point position, Point direction)
+    {
+        var newPosition = position + direction;
+        var newTile = _map[newPosition.X, newPosition.Y];
+        if (newTile != '.')
+        {
+            Move(newPosition, direction);
+        }
+
+        _map[newPosition.X, newPosition.Y] = _map[position.X, position.Y];
+        _map[position.X, position.Y] = '.';
+    }
+}

src/AdventOfCode.Puzzles/2024/15/Part2/Part2.cs

@@ -0,0 +1,197 @@
+using System.Diagnostics;
+using System.Text;
+using AdventOfCode.Puzzles.Tools;
+
+namespace AdventOfCode.Puzzles._2024._15.Part2;
+
+public partial class Part2 : IPuzzleSolution
+{
+    private int _width;
+    private int _height;
+    private char[,] _map;
+    private string _instructions;
+    private Point _robotPosition;
+
+    public async Task<string> SolveAsync(StreamReader inputReader)
+    {
+        var mapLines = new List<string>();
+        while (await inputReader.ReadLineAsync() is { } line && !string.IsNullOrWhiteSpace(line))
+        {
+            mapLines.Add(line);
+        }
+
+        _width = mapLines[0].Length * 2;
+        _height = mapLines.Count;
+        _map = new char[_width, _height];
+
+        for (int y = 0; y < _height; y++)
+        {
+            for (int x = 0; x < mapLines[0].Length; x++)
+            {
+                var character = mapLines[y][x];
+
+                if (character == '@')
+                {
+                    _robotPosition = new Point(x * 2, y);
+                    _map[x * 2, y] = '@';
+                    _map[x * 2 + 1, y] = '.';
+                }
+                else if (character == '#')
+                {
+                    _map[x * 2, y] = '#';
+                    _map[x * 2 + 1, y] = '#';
+                }
+                else if (character == '.')
+                {
+                    _map[x * 2, y] = '.';
+                    _map[x * 2 + 1, y] = '.';
+                }
+                else if (character == 'O')
+                {
+                    _map[x * 2, y] = '[';
+                    _map[x * 2 + 1, y] = ']';
+                }
+            }
+        }
+
+        StringBuilder instructions = new();
+        while (await inputReader.ReadLineAsync() is { } line)
+        {
+            instructions.Append(line);
+        }
+
+        _instructions = instructions.ToString();
+
+        foreach (var instruction in _instructions)
+        {
+            MoveRobot(instruction);
+        }
+
+        var total = 0;
+        for (int y = 0; y < _height; y++)
+        {
+            for (int x = 0; x < _width; x++)
+            {
+                if (_map[x, y] == '[')
+                {
+                    total += y * 100 + x;
+                }
+            }
+        }
+
+        return total.ToString();
+    }
+
+    private void OutputMap()
+    {
+        for (int y = 0; y < _height; y++)
+        {
+            for (int x = 0; x < _width; x++)
+            {
+                Debug.Write(_map[x, y]);
+            }
+            Debug.WriteLine("");
+        }
+    }
+
+    private void MoveRobot(char instruction)
+    {
+        var direction = instruction switch
+        {
+            '^' => new Point(0, -1),
+            '>' => new Point(1, 0),
+            'v' => new Point(0, 1),
+            '<' => new Point(-1, 0),
+            _ => throw new InvalidOperationException()
+        };
+
+        if (CanMove(_robotPosition, direction))
+        {
+            //OutputMap();
+            Move(_robotPosition, direction);
+            _robotPosition += direction;
+        }
+    }
+
+    private bool CanMove(Point position, Point direction)
+    {
+        var newPosition = position + direction;
+        var currentTile = _map[position.X, position.Y];
+
+        if (currentTile == '.')
+        {
+            return true;
+        }
+
+        if (currentTile == '#')
+        {
+            return false;
+        }
+
+        var newTile = _map[newPosition.X, newPosition.Y];
+
+        if (currentTile == '[' || currentTile == ']')
+        {
+            if ((currentTile == ']' && direction == (-1, 0)) ||
+                (currentTile == '[' && direction == (1, 0)))
+            {
+                return CanMove(newPosition, direction);
+            }
+
+            if (currentTile == ']' && (direction == (0, -1) || direction == (0, 1)))
+            {
+                return CanMove(newPosition, direction) && CanMove(newPosition + (-1, 0), direction);
+            }
+
+            if (currentTile == '[' && (direction == (0, -1) || direction == (0, 1)))
+            {
+                return CanMove(newPosition, direction) && CanMove(newPosition + (1, 0), direction);
+            }
+
+            return CanMove(newPosition, direction);
+        }
+
+        if (currentTile == '@')
+        {
+            return CanMove(newPosition, direction);
+        }
+
+        throw new InvalidOperationException();
+    }
+
+    private void Move(Point position, Point direction)
+    {
+        var newPosition = position + direction;
+
+        var currentTile = _map[position.X, position.Y];
+        var newTile = _map[newPosition.X, newPosition.Y];
+
+        if (direction == (-1, 0) || direction == (1, 0))
+        {
+            if (newTile != '.')
+            {
+                Move(newPosition, direction);
+            }
+        }
+        else
+        {
+            if (newTile == '[')
+            {
+                Move(newPosition + (1, 0), direction);
+                Move(newPosition, direction);
+            }
+            else if (newTile == ']')
+            {
+                Move(newPosition + (-1, 0), direction);
+                Move(newPosition, direction);
+            }
+            else if (newTile != '.')
+            {
+                Move(newPosition, direction);
+            }
+        }
+
+        _map[newPosition.X, newPosition.Y] = _map[position.X, position.Y];
+        _map[position.X, position.Y] = '.';
+    }
+}

src/AdventOfCode.Puzzles/2024/15/TestData.txt

@@ -0,0 +1,21 @@
+##########
+#..O..O.O#
+#......O.#
+#.OO..O.O#
+#[email protected].#
+#O#..O...#
+#O..O..O.#
+#.OO.O.OO#
+#....O...#
+##########
+
+<vv>^<v^>v>^vv^v>v<>v^v<v<^vv<<<^><<><>>v<vvv<>^v^>^<<<><<v<<<v^vv^v>^
+vvv<<^>^v^^><<>>><>^<<><^vv^^<>vvv<>><^^v>^>vv<>v<<<<v<^v>^<^^>>>^<v<v
+><>vv>v^v^<>><>>>><^^>vv>v<^^^>>v^v^<^^>v^^>v^<^v>v<>>v^v^<v>v^^<^^vv<
+<<v<^>>^^^^>>>v^<>vvv^><v<<<>^^^vv^<vvv>^>v<^^^^v<>^>vvvv><>>v^<<^^^^^
+^><^><>>><>^^<<^^v>>><^<v>^<vv>>v>>>^v><>^v><<<<v>>v<v<v>vvv>^<><<>^><
+^>><>^v<><^vvv<^^<><v<<<<<><^v<<<><<<^^<v<^^^><^>>^<v^><<<^>>^v<v^v<v^
+>^>>^v>vv>^<<^v<>><<><<v<<v><>v<^vv<<<>^^v^>^^>>><<^v>>v^v><^^>>^<>vv^
+<><^^>^^^<><vvvvv^v<v<<>^v<v>v<<^><<><<><<<^^<<<^<<>><<><^^^>^^<>^>v<>
+^^>vv<^v^v<vv>^<><v<^v>^^^>>>^^vvv^>vvv<>>>^<^>>>>>^<<^v>^vvv<>^<><<v>
+v^^>>><<^^<>>^v^<v^vv<>v^<<>^<^v^v><^<<<><<^<v><v<>vv>>v><v^<vv<>v^<<^