Add day 2

DayBenchmarker.cs

@@ -7,7 +7,7 @@ namespace AdventOfCode;
 [MemoryDiagnoser(false)]
 public class DayBenchmark
 {
-    private Day Day { get; } = new Day1();
+    private Day Day { get; } = new Day2();
 
     [GlobalSetup]
     public void Setup()

Days/Day2.cs

@@ -0,0 +1,139 @@
+using Spectre.Console;
+
+namespace AdventOfCode.Days;
+
+public class Day2 : Day
+{
+    public override int Number => 2;
+    public override string Name => "Red-Nosed Reports";
+
+    public override void RunPart1(bool display = true)
+    {
+        var safeReports = 0;
+
+        foreach (var line in Input.AsSpan().EnumerateLines())
+        {
+            var isSafe = true;
+            var levels = line.Split(' ');
+
+            var previousDirection = 0;
+            var previousLevel = int.MinValue;
+            foreach (var levelRange in levels)
+            {
+                var level = int.Parse(line[levelRange]);
+
+                // First level, skip to next
+                if (previousLevel == int.MinValue)
+                {
+                    previousLevel = level;
+
+                    continue;
+                }
+
+                // Check that direction is preserved
+                var direction = level - previousLevel;
+
+                if (previousDirection != 0 && Math.Sign(direction) != Math.Sign(previousDirection))
+                {
+                    isSafe = false;
+                    break;
+                }
+
+                // Check that distance >= 1 and <= 3
+                if (Math.Abs(direction) is < 1 or > 3)
+                {
+                    isSafe = false;
+                    break;
+                }
+
+                previousLevel = level;
+                previousDirection = direction;
+            }
+
+            if (isSafe)
+            {
+                safeReports++;
+            }
+        }
+
+        if (display)
+        {
+            AnsiConsole.MarkupLine($"[green]Number of safe reports: [yellow]{safeReports}[/][/]");
+        }
+    }
+
+    public override void RunPart2(bool display = true)
+    {
+        var safeReports = 0;
+
+        foreach (var line in Input.AsSpan().EnumerateLines())
+        {
+            if (IsSafe(line))
+            {
+                safeReports++;
+            }
+        }
+
+        if (display)
+        {
+            AnsiConsole.MarkupLine($"[green]Number of safe reports: [yellow]{safeReports}[/][/]");
+        }
+
+        return;
+
+        bool IsSafe(ReadOnlySpan<char> line, Range? toSkip = null)
+        {
+            var levels = line.Split(' ');
+
+            var previousDirection = 0;
+            var previousLevel = int.MinValue;
+            Range previousLevelRange = default;
+            Range firstLevelRange = default;
+
+            foreach (var levelRange in levels)
+            {
+                if (levelRange.Equals(toSkip))
+                {
+                    // This level can be skipped using the problem dampener
+                    continue;
+                }
+
+                var level = int.Parse(line[levelRange]);
+
+                // First level, skip to next
+                if (previousLevel == int.MinValue)
+                {
+                    previousLevel = level;
+                    previousLevelRange = levelRange;
+                    firstLevelRange = levelRange;
+
+                    continue;
+                }
+
+                // Check that direction is preserved
+                var direction = level - previousLevel;
+
+                if (previousDirection != 0 && Math.Sign(direction) != Math.Sign(previousDirection))
+                {
+                    // Also try by removing current or previous level if it's first try (problem dampener)
+                    return toSkip is null
+                           && (IsSafe(line, levelRange) || IsSafe(line, previousLevelRange) || IsSafe(line, firstLevelRange));
+                }
+
+                // Check that distance >= 1 and <= 3
+                if (Math.Abs(direction) is < 1 or > 3)
+                {
+                    // Also try by removing current or previous level if it's first try (problem dampener)
+                    return toSkip is null
+                           && (IsSafe(line, levelRange) || IsSafe(line, previousLevelRange) || IsSafe(line, firstLevelRange));
+                }
+
+                previousLevel = level;
+                previousDirection = direction;
+                previousLevelRange = levelRange;
+            }
+
+            return true;
+        }
+    }
+}