From e7af72913a2030c2f543b6bbf5f65ac9ab03db47 Mon Sep 17 00:00:00 2001
From: Stevan Freeborn <65925598+StevanFreeborn@users.noreply.github.com>
Date: Sat, 16 Dec 2023 20:36:09 -0600
Subject: [PATCH] feat: solve part 1 and part 2

---
 .../CosmicExpansion.Tests.csproj              |   6 +
 11/CosmicExpansion.Tests/UnitTest1.cs         |  10 -
 11/CosmicExpansion.Tests/UniverseTests.cs     | 143 +++++++++++++++
 11/CosmicExpansion/Program.cs                 | 173 +++++++++++++++++-
 4 files changed, 320 insertions(+), 12 deletions(-)
 delete mode 100644 11/CosmicExpansion.Tests/UnitTest1.cs
 create mode 100644 11/CosmicExpansion.Tests/UniverseTests.cs

diff --git a/11/CosmicExpansion.Tests/CosmicExpansion.Tests.csproj b/11/CosmicExpansion.Tests/CosmicExpansion.Tests.csproj
index 74d97f9..08f293c 100644
--- a/11/CosmicExpansion.Tests/CosmicExpansion.Tests.csproj
+++ b/11/CosmicExpansion.Tests/CosmicExpansion.Tests.csproj
@@ -27,4 +27,10 @@
     <ProjectReference Include="..\CosmicExpansion\CosmicExpansion.csproj" />
   </ItemGroup>
 
+  <ItemGroup>
+    <Content Include="..\INPUT.txt">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
+  </ItemGroup>
+
 </Project>
diff --git a/11/CosmicExpansion.Tests/UnitTest1.cs b/11/CosmicExpansion.Tests/UnitTest1.cs
deleted file mode 100644
index f54379d..0000000
--- a/11/CosmicExpansion.Tests/UnitTest1.cs
+++ /dev/null
@@ -1,10 +0,0 @@
-namespace CosmicExpansion.Tests;
-
-public class UnitTest1
-{
-    [Fact]
-    public void Test1()
-    {
-
-    }
-}
\ No newline at end of file
diff --git a/11/CosmicExpansion.Tests/UniverseTests.cs b/11/CosmicExpansion.Tests/UniverseTests.cs
new file mode 100644
index 0000000..e99b316
--- /dev/null
+++ b/11/CosmicExpansion.Tests/UniverseTests.cs
@@ -0,0 +1,143 @@
+namespace CosmicExpansion.Tests;
+
+public class UniverseTests
+{
+  [Theory]
+  [MemberData(nameof(TestData.ParseTestData), MemberType = typeof(TestData))]
+  public void Parse_WhenGivenUniverseWithGalaxies_ItShouldReturnListOfGalaxies(string[] givenInput, Universe expectedUniverse)
+  {
+    var result = Universe.Parse(givenInput);
+    result.Should().BeEquivalentTo(expectedUniverse);
+  }
+
+  [Theory]
+  [MemberData(nameof(TestData.GetShortestPathsBetweenGalaxiesTestData), MemberType = typeof(TestData))]
+  public void GetShortestPathsBetweenGalaxies_WhenGivenUniverseWithGalaxies_ItShouldReturnShortestPathsBetweenGalaxies(Universe givenUniverse, int expectedNumberOrPaths)
+  {
+    var result = givenUniverse.GetShortestPathsBetweenGalaxies();
+    result.Count.Should().Be(expectedNumberOrPaths);
+  }
+
+  [Theory]
+  [MemberData(nameof(TestData.SumOfShortestPathsBetweenGalaxiesTestData), MemberType = typeof(TestData))]
+  public void SumOfShortestPathsBetweenGalaxies_WhenGivenUniverseWithGalaxies_ItShouldReturnSumOfShortestPathsBetweenGalaxies(Universe givenUniverse, int expectedSumOfShortestPaths)
+  {
+    givenUniverse.SumOfShortestPathsBetweenGalaxies.Should().Be(expectedSumOfShortestPaths);
+  }
+
+  [Theory]
+  [MemberData(nameof(TestData.CalculateDistanceBetweenGalaxiesTestData), MemberType = typeof(TestData))]
+  public void CalculateDistanceBetweenGalaxies_WhenGivenTwoGalaxies_ItShouldReturnDistanceBetweenGalaxies(Galaxy startGalaxy, Galaxy endGalaxy, int expectedDistance)
+  {
+    var result = Universe.CalculateDistanceBetweenGalaxies(startGalaxy, endGalaxy);
+    result.Should().Be(expectedDistance);
+  }
+
+  [Fact]
+  public void SumOfShortestPathsBetweenGalaxies_WhenGivenInput_ItShouldReturnSumOfShortestPathsBetweenGalaxies()
+  {
+    var input = File.ReadAllLines("INPUT.txt");
+    var universe = Universe.Parse(input);
+    universe.SumOfShortestPathsBetweenGalaxies.Should().Be(10292708);
+  }
+
+  [Fact]
+  public void SumOfShortestPathsBetweenGalaxies_WhenGivenInputAndIsPart2_ItShouldReturnSumOfShortestPathsBetweenGalaxies()
+  {
+    var input = File.ReadAllLines("INPUT.txt");
+    var universe = Universe.Parse(input, 1_000_000);
+    universe.SumOfShortestPathsBetweenGalaxies.Should().Be(790194712336);
+  }
+
+
+
+  public static class TestData
+  {
+    private static readonly Universe TestUniverse = new(
+      12,
+      13,
+      [
+        new(0, 4),
+        new(1, 9),
+        new(2, 0),
+        new(5, 8),
+        new(6, 1),
+        new(7, 12),
+        new(10, 9),
+        new(11, 0),
+        new(11, 5),
+      ]
+    );
+
+    public static IEnumerable<object[]> ParseTestData =>
+      new List<object[]>
+      {
+        new object[]
+        {
+          new string[]
+          {
+            "...#......",
+            ".......#..",
+            "#.........",
+            "..........",
+            "......#...",
+            ".#........",
+            ".........#",
+            "..........",
+            ".......#..",
+            "#...#.....",
+          },
+          TestUniverse,
+        }
+      };
+
+    public static IEnumerable<object[]> GetShortestPathsBetweenGalaxiesTestData =>
+      new List<object[]>
+      {
+        new object[]
+        {
+          TestUniverse,
+          36,
+        }
+      };
+
+    public static IEnumerable<object[]> SumOfShortestPathsBetweenGalaxiesTestData =>
+      new List<object[]>
+      {
+        new object[]
+        {
+          TestUniverse,
+          374,
+        }
+      };
+
+    public static IEnumerable<object[]> CalculateDistanceBetweenGalaxiesTestData =>
+      new List<object[]>
+      {
+        new object[]
+        {
+          TestUniverse.Galaxies[4],
+          TestUniverse.Galaxies[8],
+          9,
+        },
+        new object[]
+        {
+          TestUniverse.Galaxies[0],
+          TestUniverse.Galaxies[6],
+          15,
+        },
+        new object[]
+        {
+          TestUniverse.Galaxies[2],
+          TestUniverse.Galaxies[5],
+          17,
+        },
+        new object[]
+        {
+          TestUniverse.Galaxies[7],
+          TestUniverse.Galaxies[8],
+          5,
+        }
+      };
+  }
+}
\ No newline at end of file
diff --git a/11/CosmicExpansion/Program.cs b/11/CosmicExpansion/Program.cs
index 3751555..137ec62 100644
--- a/11/CosmicExpansion/Program.cs
+++ b/11/CosmicExpansion/Program.cs
@@ -1,2 +1,171 @@
-// See https://aka.ms/new-console-template for more information
-Console.WriteLine("Hello, World!");
+using System.Diagnostics;
+
+namespace CosmicExpansion;
+
+public class Program
+{
+  public static async Task<int> Main(string[] args)
+  {
+    if (args.Length is 0)
+    {
+      Console.WriteLine("Please provide a path to the input file.");
+      return -1;
+    }
+
+    if (File.Exists(args[0]) is false)
+    {
+      Console.WriteLine("The provided file does not exist.");
+      return -2;
+    }
+
+    var isPart2 = args.Length > 1 && args[1] == "part2";
+    var input = await File.ReadAllLinesAsync(args[0]);
+
+    var stopwatch = new Stopwatch();
+    stopwatch.Start();
+
+    var universe = isPart2
+      ? Universe.Parse(input, 1_000_000)
+      : Universe.Parse(input);
+
+    var result = universe.SumOfShortestPathsBetweenGalaxies;
+
+    stopwatch.Stop();
+
+    Console.WriteLine($"The sum of the shortest paths between galaxies is {result}. ({stopwatch.ElapsedMilliseconds}ms)");
+
+    return (int)result;
+  }
+}
+
+public class Universe(
+  int height,
+  int width,
+  List<Galaxy> galaxies
+)
+{
+  private const char GalaxySymbol = '#';
+  public int Height { get; init; } = height;
+  public int Width { get; init; } = width;
+  public List<Galaxy> Galaxies { get; init; } = galaxies;
+  public long SumOfShortestPathsBetweenGalaxies =>
+    GetShortestPathsBetweenGalaxies()
+    .Values
+    .Sum();
+
+  public Dictionary<(int galaxyOneIndex, int galaxyTwoIndex), long> GetShortestPathsBetweenGalaxies()
+  {
+    var shortestPaths = new Dictionary<(int galaxyOneIndex, int galaxyTwoIndex), long>();
+
+    for (int i = 0; i < Galaxies.Count; i++)
+    {
+      var galaxyOne = Galaxies[i];
+
+      for (int j = i + 1; j < Galaxies.Count; j++)
+      {
+        var galaxyTwo = Galaxies[j];
+
+        if (shortestPaths.ContainsKey((i, j)) || shortestPaths.ContainsKey((j, i)))
+        {
+          continue;
+        }
+
+        var shortestPath = CalculateDistanceBetweenGalaxies(galaxyOne, galaxyTwo);
+        shortestPaths.Add((i, j), shortestPath);
+      }
+    }
+
+    return shortestPaths;
+  }
+
+  public static long CalculateDistanceBetweenGalaxies(Galaxy galaxyOne, Galaxy galaxyTwo) =>
+    Math.Abs(galaxyTwo.Row - galaxyOne.Row) + Math.Abs(galaxyTwo.Column - galaxyOne.Column);
+
+  public static Universe Parse(string[] input, int expandFactor = 2)
+  {
+    var emptyRows = new List<int>();
+    var emptyColumns = new List<int>();
+    var galaxies = new List<Galaxy>();
+
+    for (int i = 0; i < input.Length; i++)
+    {
+      var currentRow = input[i];
+
+      if (currentRow.Contains(GalaxySymbol) is false)
+      {
+        emptyRows.Add(i);
+      }
+    }
+
+    for (int i = 0; i < input[0].Length; i++)
+    {
+      var galaxyInColumn = false;
+
+      for (int j = 0; j < input.Length; j++)
+      {
+        var currentPosition = input[j][i];
+
+        if (currentPosition == GalaxySymbol)
+        {
+          galaxyInColumn = true;
+          break;
+        }
+      }
+
+      if (galaxyInColumn is false)
+      {
+        emptyColumns.Add(i);
+      }
+    }
+
+    for (int i = 0; i < input.Length; i++)
+    {
+      var currentRow = input[i];
+
+      for (int j = 0; j < currentRow.Length; j++)
+      {
+        var currentPosition = currentRow[j];
+
+        if (currentPosition == GalaxySymbol)
+        {
+          var numOfEmptyRowsBefore = emptyRows.Where(row => row < i).Count();
+          var rowOffset = numOfEmptyRowsBefore is 0
+            ? 0
+            : (numOfEmptyRowsBefore * expandFactor) - numOfEmptyRowsBefore;
+
+          var numOfEmptyColumnsBefore = emptyColumns.Where(column => column < j).Count();
+          var columnOffset = numOfEmptyColumnsBefore is 0
+            ? 0
+            : (numOfEmptyColumnsBefore * expandFactor) - numOfEmptyColumnsBefore;
+
+          galaxies.Add(new Galaxy(i + rowOffset, j + columnOffset));
+        }
+      }
+    }
+
+    var heightOffset = emptyRows.Count is 0
+      ? 0
+      : (emptyRows.Count * expandFactor) - emptyRows.Count;
+    var widthOffset = emptyColumns.Count is 0
+      ? 0
+      : (emptyColumns.Count * expandFactor) - emptyColumns.Count;
+
+    var height = input.Length + heightOffset;
+    var width = input[0].Length + widthOffset;
+
+    return new Universe(
+      height,
+      width,
+      galaxies
+    );
+  }
+}
+
+public class Galaxy(
+  long row,
+  long column
+)
+{
+  public long Row { get; init; } = row;
+  public long Column { get; init; } = column;
+}
\ No newline at end of file