D11: Both parts solved, will also push D10 later, got lazy.

Author: Formula-9

2023.csproj

@@ -12,6 +12,7 @@
  <PackageReference Include="AoCHelper" Version="3.1.0" />
  <PackageReference Include="Microsoft.Extensions.Configuration" Version="8.0.0" />
  <PackageReference Include="Microsoft.Extensions.Configuration.Json" Version="8.0.0" />
+ <PackageReference Include="System.Interactive" Version="6.0.1" />
  </ItemGroup>
 
 </Project>

Program.cs

@@ -1,13 +1,15 @@
 using AoCHelper;
 using Formula9.AdventOfCode.Solutions2023.Day10;
+using Formula9.AdventOfCode.Solutions2023.Day11;
+using Formula9.AdventOfCode.Utils;
 
 namespace Formula9.AdventOfCode;
 
 public class Program
 {
  public static void Main(string[] args)
  {
- Type day = typeof(Day_10);
+ Type day = typeof(Day_11);
  // var _d = Activator.CreateInstance(day) as AdventOfCodeProblem;
  // Console.WriteLine(_d.Solve_1().AsTask().Result);
  // Console.WriteLine(_d.Solve_2().AsTask().Result);

Runner/AdventOfCodeFetcher.cs

@@ -15,13 +15,16 @@ private AdventOfCodeFetcher()
  Client = new HttpClient(ClientHandler);
  }
 
+
+
  public string GetInputFromWeb(int year, int day, string saveToPath)
  {
+ ThrowIfPuzzleIsNotRevealedYet(year, day);
  string result = FetchInputForDayFromWeb(year, day);
  if (!string.IsNullOrEmpty(saveToPath))
  {
- string dirName = Path.GetDirectoryName(saveToPath);
- if (!Directory.Exists(dirName))
+ string? dirName = Path.GetDirectoryName(saveToPath);
+ if (dirName != null && !Directory.Exists(dirName))
  {
  Directory.CreateDirectory(dirName);
  }
@@ -32,6 +35,15 @@ public string GetInputFromWeb(int year, int day, string saveToPath)
  return result;
  }
 
+ private static void ThrowIfPuzzleIsNotRevealedYet(int year, int day)
+ {
+ var date = DateTime.UtcNow;
+ if (year > date.Year || (year == date.Year && day > date.Day) || (year == date.Year && day == date.Day && date.Hour < 5))
+ {
+ throw new PuzzleNotRevealedExceptionException();
+ }
+ }
+
  private string FetchInputForDayFromWeb(int year, int day)
  {
  var response = Client.GetAsync($"https://adventofcode.com/{year}/day/{day}/input").Result;

Runner/PuzzleNotRevealedException.cs

@@ -0,0 +1,12 @@
+using System.Runtime.Serialization;
+
+namespace Formula9.AdventOfCode.Runner;
+
+[Serializable]
+public class PuzzleNotRevealedExceptionException : Exception
+{
+ public PuzzleNotRevealedExceptionException() { }
+ public PuzzleNotRevealedExceptionException(string message) : base(message) { }
+ public PuzzleNotRevealedExceptionException(string message, Exception inner) : base(message, inner) { }
+ protected PuzzleNotRevealedExceptionException(SerializationInfo info, StreamingContext context) : base(info, context) { }
+}

Solutions/Day11/Day11.cs

@@ -4,9 +4,82 @@ namespace Formula9.AdventOfCode.Solutions2023.Day11;
 
 public class Day_11 : AdventOfCodeProblem
 {
- public Day_11() : base(2023, 11) { }
 
- public override ValueTask<string> Solve_1() => new("Solution 1");
+ public ISet<int> EmptyRows { get; init; }
+ public ISet<int> EmptyCols { get; init; }
+ public ISet<(int y, int x)> Stars { get; init; }
+ public ISet<((int y, int x) left, (int y, int x) right)> StarPairs { get; private set; }
 
- public override ValueTask<string> Solve_2() => new("Solution 2");
+ public Day_11() : base(2023, 11) 
+ {
+ EmptyRows = new HashSet<int>();
+ EmptyCols = new HashSet<int>();
+ Stars = new HashSet<(int y, int x)>();
+ StarPairs = new HashSet<((int y, int x) left, (int y, int x) right)>();
+ ReadData();
+ }
+
+ public void ReadData()
+ {
+ var grid = Input.SplitByNewline();
+ foreach ((int y, var line) in grid.Enumerate())
+ {
+ if (IsLineEmpty(line))
+ {
+ EmptyRows.Add(y);
+ continue;
+ }
+ 
+ foreach ((int x, char c) in line.Enumerate())
+ {
+ if (c == '#') Stars.Add((y, x));
+ }
+ }
+
+ foreach (int x in Enumerable.Range(0, grid[0].Length))
+ {
+ if (Enumerable.Range(0, grid.Length).Select(y => grid[y][x]).ToHashSet().Count == 1)
+ {
+ EmptyCols.Add(x);
+ }
+ }
+
+ StarPairs = Stars.Combinations(2).Select(enumerable => (left: enumerable.First(), right: enumerable.Last())).ToHashSet();
+ }
+
+ public long FindShortestPath((int x, int y) left, (int x, int y) right, int expansionLevel)
+ {
+ (int smallestX, int smallestY) = (Math.Min(left.x, right.x), Math.Min(left.y, right.y));
+ (int biggestX, int biggestY) = (Math.Max(left.x, right.x), Math.Max(left.y, right.y));
+ (long dx, long dy) = (Math.Abs(left.x - right.x), Math.Abs(left.y - right.y));
+ foreach (var row in EmptyRows)
+ {
+ for (int x = smallestX; x < biggestX; x++)
+ {
+ if (row == x)
+ {
+ dx += expansionLevel;
+ break;
+ }
+ }
+ }
+ foreach (var col in EmptyCols)
+ {
+ for (int y = smallestY; y < biggestY; y++)
+ {
+ if (col == y)
+ {
+ dy += expansionLevel;
+ break;
+ }
+ }
+ }
+ return dx + dy;
+ } 
+
+ public static bool IsLineEmpty(string l) => l.Select(c => c).ToHashSet().Count == 1;
+
+ public override ValueTask<string> Solve_1() => new(StarPairs.Sum(pairTuple => FindShortestPath(pairTuple.left, pairTuple.right, 1)).ToString());
+
+ public override ValueTask<string> Solve_2() => new(StarPairs.Sum(pairTuple => FindShortestPath(pairTuple.left, pairTuple.right, 1_000_000 - 1)).ToString());
 }

Utils/EnumerableUtils.cs

@@ -46,4 +46,24 @@ public static T Next<T>(this IEnumerator<T> enumerator)
  }
 
  public static double Product<T>(this IEnumerable<T> values, Func<T, double> keySelector) => values.Aggregate(1d, (acc, el) => acc * keySelector(el));
+
+ public static IEnumerable<(int, T)> Enumerate<T>(this IEnumerable<T> values, int start = 0)
+ {
+ foreach (T element in values)
+ {
+ yield return (start, element);
+ start++;
+ }
+ yield break;
+ }
+
+ public static IEnumerable<IEnumerable<T>> Combinations<T>(this IEnumerable<T> values, int k)
+ {
+ return k == 0 
+ ? EnumerableEx.Return(Enumerable.Empty<T>()) 
+ : values.SelectMany((e, i) => 
+ values.Skip(i + 1)
+ .Combinations(k - 1)
+ .Select(c => EnumerableEx.Return(e).Concat(c)));
+ }
 }