Day 25

Merry Christmas!

src/25.cs

@@ -0,0 +1,104 @@
+namespace aoc2024;
+
+internal class Day25 : Day
+{
+    private List<List<int>> locks = [];
+    private List<List<int>> keys = [];
+
+    internal override void Parse()
+    {
+        var lines = Util.Parsing.ReadAllLines($"{GetDay()}").ToList();
+        var type = -1;
+        var grid = new bool[5, 5];
+        int count = 0;
+        bool checking = false;
+        foreach (var line in lines)
+        {
+            if (line.Length == 0)
+            {
+                type = -1;
+                count = 0;
+                continue;
+            }
+
+            if (type == -1)
+            {
+                type = line == "#####" ? 0 : 1;
+            }
+
+            if (line is "#####" or "....." && (!checking || count == 5))
+            {
+                checking = true;
+
+                if (count == 5)
+                {
+                    List<int> arrangement = [];
+                    for (int x = 0; x < grid.GetLength(1); x++)
+                    {
+                        int height = 0;
+                        for (int y = 0; y < grid.GetLength(0); y++)
+                        {
+                            if (grid[x, y])
+                            {
+                                height++;
+                            }
+                        }
+
+                        arrangement.Add(height);
+                    }
+
+                    if (type == 0)
+                    {
+                        locks.Add(arrangement);
+                    }
+                    else
+                    {
+                        keys.Add(arrangement);
+                    }
+
+                    checking = false;
+                }
+                continue;
+            }
+
+            for (int i = 0; i < line.Length; i++)
+            {
+                grid[i, count] = line[i] == '#';
+            }
+
+            count++;
+        }
+    }
+
+    internal override string Part1()
+    {
+        long matches = 0;
+        foreach (var key in keys)
+        {
+            foreach (var lck in locks)
+            {
+                bool match = true;
+                for (int i = 0; i < 5; i++)
+                {
+                    if (key[i] + lck[i] > 5)
+                    {
+                        match = false;
+                        break;
+                    }
+                }
+
+                if (match)
+                {
+                    matches++;
+                }
+            }
+        }
+
+        return $"Lock/key fits: <+white>{matches}";
+    }
+
+    internal override string Part2()
+    {
+        return "<red>M<green>e<red>r<green>r<red>y <green>C<red>h<green>r<red>i<green>s<red>t<green>m<red>a<green>s<red>!";
+    }
+}