From d839ab7ec93b9b6a1a30c0faa533b72cc9b25ccf Mon Sep 17 00:00:00 2001
From: Eveldee <eveldee0680@live.fr>
Date: Fri, 24 Jan 2025 10:19:12 +0100
Subject: [PATCH] Add day 10

---
 DayBenchmarker.cs |   2 +-
 Days/Day10.cs     | 169 ++++++++++++++++++++++++++++++++++++++++++++++
 Inputs/Day10.txt  |  60 ++++++++++++++++
 3 files changed, 230 insertions(+), 1 deletion(-)
 create mode 100644 Days/Day10.cs
 create mode 100644 Inputs/Day10.txt

diff --git a/DayBenchmarker.cs b/DayBenchmarker.cs
index fac650b..4c3100b 100644
--- a/DayBenchmarker.cs
+++ b/DayBenchmarker.cs
@@ -7,7 +7,7 @@ namespace AdventOfCode;
 [MemoryDiagnoser(false)]
 public class DayBenchmark
 {
-    private Day Day { get; } = new Day3();
+    private Day Day { get; } = new Day10();
 
     [GlobalSetup]
     public void Setup()
diff --git a/Days/Day10.cs b/Days/Day10.cs
new file mode 100644
index 0000000..909f3f1
--- /dev/null
+++ b/Days/Day10.cs
@@ -0,0 +1,169 @@
+using System.Collections.Frozen;
+using System.Numerics;
+using Spectre.Console;
+
+namespace AdventOfCode.Days;
+
+public class Day10 : Day
+{
+    public override int Number => 10;
+    public override string Name => "Hoof It";
+
+    private const int MapSize = 60;
+
+    public override void RunPart1(bool display = true)
+    {
+        var hikingTrailsScores = 0;
+
+        var (heightMap, trailHeads) = ParseMap();
+
+        var hikingTrails = new HashSet<Point>();
+
+        foreach (var trailHead in trailHeads)
+        {
+            hikingTrails.Clear();
+
+            GetHikingTrailScore(trailHead, -1);
+
+            hikingTrailsScores += hikingTrails.Count;
+        }
+
+        if (display)
+        {
+            AnsiConsole.MarkupLine($"[green]Sum of scores of hiking trails: [yellow]{hikingTrailsScores}[/][/]");
+        }
+
+        return;
+
+        void GetHikingTrailScore(Point position, int previousHeight)
+        {
+            // Out of bounds
+            if (position is { X: < 0 or >= MapSize } or { Y: < 0 or >= MapSize })
+            {
+                return;
+            }
+
+            var height = heightMap[position.X, position.Y];
+
+            if (height - previousHeight is not 1)
+            {
+                return;
+            }
+
+            if (height == 9)
+            {
+                hikingTrails.Add(position);
+            }
+
+
+            GetHikingTrailScore(position + (1, 0), height);
+            GetHikingTrailScore(position + (-1, 0), height);
+            GetHikingTrailScore(position + (0, 1), height);
+            GetHikingTrailScore(position + (0, -1), height);
+        }
+    }
+
+    public override void RunPart2(bool display = true)
+    {
+        var (heightMap, trailHeads) = ParseMap();
+
+        var totalRating = 0;
+
+        foreach (var trailHead in trailHeads)
+        {
+            GetHikingTrailRating(trailHead, -1);
+        }
+
+        if (display)
+        {
+            AnsiConsole.MarkupLine($"[green]Total rating of hiking trails: [yellow]{totalRating}[/][/]");
+        }
+
+        return;
+
+        void GetHikingTrailRating(Point position, int previousHeight)
+        {
+            // Out of bounds
+            if (position is { X: < 0 or >= MapSize } or { Y: < 0 or >= MapSize })
+            {
+                return;
+            }
+
+            var height = heightMap[position.X, position.Y];
+
+            if (height - previousHeight is not 1)
+            {
+                return;
+            }
+
+            if (height == 9)
+            {
+                totalRating++;
+            }
+
+            GetHikingTrailRating(position + (1, 0), height);
+            GetHikingTrailRating(position + (-1, 0), height);
+            GetHikingTrailRating(position + (0, 1), height);
+            GetHikingTrailRating(position + (0, -1), height);
+        }
+    }
+
+    private (byte[,] HeightMap, List<Point> TrailHeads) ParseMap()
+    {
+        var heightMap = new byte[MapSize, MapSize];
+        var trailHeads = new List<Point>();
+
+        var y = 0;
+        foreach (var line in Input.AsSpan().EnumerateLines())
+        {
+            var x = 0;
+            foreach (var height in line)
+            {
+                var heightValue = height - '0';
+
+                if (heightValue is 0)
+                {
+                    trailHeads.Add(new Point(x, y));
+                }
+
+                heightMap[x, y] = (byte)heightValue;
+
+                x++;
+            }
+
+            y++;
+        }
+
+        return (heightMap, trailHeads);
+    }
+
+
+    private readonly record struct Point(int X, int Y)
+        : IAdditionOperators<Point, Point, Point>,
+            ISubtractionOperators<Point, Point, Point>,
+            IMultiplyOperators<Point, int, Point>
+    {
+        public static Point operator +(Point left, Point right)
+        {
+            return new Point(left.X + right.X, left.Y + right.Y);
+        }
+
+        public static Point operator -(Point left, Point right)
+        {
+            return new Point(left.X - right.X, left.Y - right.Y);
+        }
+
+        public static Point operator *(Point left, int right)
+        {
+            return new Point(left.X * right, left.Y * right);
+        }
+
+        public static Point operator *(int left, Point right)
+        {
+            return new Point(right.X * left, right.Y * left);
+        }
+
+        public static implicit operator Point((int X, int Y) point)
+            => new(point.X, point.Y);
+    }
+}
\ No newline at end of file
diff --git a/Inputs/Day10.txt b/Inputs/Day10.txt
new file mode 100644
index 0000000..a5d8c1d
--- /dev/null
+++ b/Inputs/Day10.txt
@@ -0,0 +1,60 @@
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\ No newline at end of file