Finish day 14

7 files changed, 135 insertions, 9 deletions

diff --git a/README.md b/README.md
index e1f1f9d..ea58a4b 100644
--- a/README.md
+++ b/README.md
@@ -10,7 +10,7 @@ Repository storing my solutions to Advent of Code. See other people's solutions
 
 ### [2022](aoc-2022-dotnet)
 ![.NET](https://img.shields.io/badge/.NET-grey?logo=.NET)
-![Stars](https://img.shields.io/badge/🌟%20stars-26/50-orange)
+![Stars](https://img.shields.io/badge/🌟%20stars-28/50-orange)
 
 [awesome]: https://github.com/Bogdanp/awesome-advent-of-code
 [aoc]: https://adventofcode.com
diff --git a/aoc-2022-dotnet/Common/Vec2.fs b/aoc-2022-dotnet/Common/Vec2.fs
index 11c94aa..8835a5a 100644
--- a/aoc-2022-dotnet/Common/Vec2.fs
+++ b/aoc-2022-dotnet/Common/Vec2.fs
@@ -1,14 +1,21 @@
 namespace Common
 
+[<StructuralEquality; StructuralComparison>]
 type Vec2 =
     | Vec2 of int * int
 
+    static member x(Vec2 (x, _)) = x
+    static member y(Vec2 (_, y)) = y
+
     static member zero = Vec2(0, 0)
     static member up = Vec2(0, 1)
     static member right = Vec2(1, 0)
     static member down = Vec2(0, -1)
     static member left = Vec2(-1, 0)
 
+    static member downLeft = Vec2(-1, -1)
+    static member downRight = Vec2(1, -1)
+
     static member directions4 =
         [ Vec2.up
           Vec2.right
@@ -28,6 +35,16 @@ type Vec2 =
     static member chebyshevDist (Vec2 (x1, y1)) (Vec2 (x2, y2)) = max (abs <| x2 - x1) (abs <| y2 - y1)
     static member neighbours4 v = List.map ((+) v) Vec2.directions4
 
+    static member lineBetween(Vec2 (x1, y1), Vec2 (x2, y2)) =
+        if x1 = x2 then
+            seq { min y1 y2 .. max y1 y2 }
+            |> Seq.map (fun y -> Vec2(x1, y))
+        elif y1 = y2 then
+            seq { min x1 x2 .. max x1 x2 }
+            |> Seq.map (fun x -> Vec2(x, y1))
+        else
+            failwith "Points must be in a vertical or horizontal line!"
+
     static member inMatrix matrix (Vec2 (col, row)) =
         col >= 0
         && col < Array2D.length2 matrix
diff --git a/aoc-2022-dotnet/Day12/Program.fs b/aoc-2022-dotnet/Day12/Program.fs
index 0ccaab7..ca827ba 100644
--- a/aoc-2022-dotnet/Day12/Program.fs
+++ b/aoc-2022-dotnet/Day12/Program.fs
@@ -57,11 +57,8 @@ type Graph<'T> =
                      Some(depth)
                  else
                      bfsExplore
-                         (neighbours
-                          |> Seq.choose (fun n ->
-                              match Set.contains n explored with
-                              | true -> None
-                              | false -> Some(n, depth + 1))
+                         (neighbours - explored
+                          |> Seq.map (fun n -> (n, depth + 1))
                           |> Seq.append qt
                           |> List.ofSeq)
                          (explored + neighbours))
diff --git a/aoc-2022-dotnet/Day14/Day14.fsproj b/aoc-2022-dotnet/Day14/Day14.fsproj
new file mode 100644
index 0000000..358ef88
--- /dev/null
+++ b/aoc-2022-dotnet/Day14/Day14.fsproj
@@ -0,0 +1,26 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net7.0</TargetFramework>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Content Include="test.txt">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </Content>
+    <Content Include="input.txt">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </Content>
+    <Compile Include="Program.fs" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="FParsec" Version="1.1.1" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\Common\Common.fsproj" />
+  </ItemGroup>
+
+</Project>
diff --git a/aoc-2022-dotnet/Day14/Program.fs b/aoc-2022-dotnet/Day14/Program.fs
new file mode 100644
index 0000000..02e028c
--- /dev/null
+++ b/aoc-2022-dotnet/Day14/Program.fs
@@ -0,0 +1,80 @@
+module Day14
+
+open System.IO
+open FParsec
+open Common
+
+let sandSpawnPos = Vec2(500, 0)
+
+let sandMoveOffsets =
+    [ Vec2.down
+      Vec2.downLeft
+      Vec2.downRight ]
+
+let notIn set element = not <| Set.contains element set
+
+let buildCaveScan =
+    let parsePath =
+        let py = pint32 |>> (~-) // mirror Y coordinate
+        let ppoint = pint32 .>> (pchar ',') .>>. py |>> Vec2
+        let ppath = sepBy ppoint (pstring " -> ")
+        Util.parse ppath
+
+    let pathToPositions =
+        Seq.pairwise
+        >> Seq.collect Vec2.lineBetween
+        >> Set
+
+    Seq.map (parsePath >> pathToPositions)
+    >> Seq.reduce (+)
+
+let solution1 input =
+    let initialCaveScan = buildCaveScan input
+    let voidY = initialCaveScan |> Seq.map Vec2.y |> Seq.min
+
+    let settleNewUnit caveScan =
+        let rec fall pos =
+            if Vec2.y pos <= voidY then
+                None
+            else
+                sandMoveOffsets
+                |> Seq.map ((+) pos)
+                |> Seq.tryFind (notIn caveScan)
+                |> function
+                    | Some (nextPos) -> fall nextPos
+                    | None -> Some(pos)
+
+        caveScan
+        |> match fall sandSpawnPos with
+           | Some (settledPos) -> Set.add settledPos
+           | None -> id
+
+    initialCaveScan
+    |> Seq.unfold (fun caveScan -> Some(caveScan, settleNewUnit caveScan))
+    |> Seq.pairwise
+    |> Seq.takeWhile (fun (a, b) -> a <> b)
+    |> Seq.length
+
+let solution2 input =
+    let caveScan = buildCaveScan input
+    let floorY = caveScan |> Seq.map Vec2.y |> Seq.min |> (+) -2
+
+    let neighbours pos =
+        sandMoveOffsets
+        |> List.map ((+) pos)
+        |> List.filter (fun pos -> notIn caveScan pos && Vec2.y pos <> floorY)
+
+    let rec dfs stack visited =
+        match stack with
+        | h :: t -> dfs (List.filter (notIn visited) (neighbours h) @ t) (Set.add h visited)
+        | [] -> Set.count visited
+
+    dfs [ sandSpawnPos ] Set.empty
+
+let test = File.ReadLines("test.txt")
+assert (solution1 test = 24)
+assert (solution2 test = 93)
+
+let input = File.ReadLines("input.txt")
+printfn "%d" <| solution1 input
+printfn "%d" <| solution2 input
diff --git a/aoc-2022-dotnet/README.md b/aoc-2022-dotnet/README.md
index dbcb833..84a39ce 100644
--- a/aoc-2022-dotnet/README.md
+++ b/aoc-2022-dotnet/README.md
@@ -1,6 +1,6 @@
 # Advent of Code 2022 in .NET
 ![.NET](https://img.shields.io/badge/.NET-grey?logo=.NET)
-![Stars](https://img.shields.io/badge/🌟%20stars-26/50-orange)
+![Stars](https://img.shields.io/badge/🌟%20stars-28/50-orange)
 
 ## Progress
 | Day                             | Part 1 | Part 2 |
@@ -18,7 +18,7 @@
 | Day 11: Monkey in the Middle    |   🌟   |   🌟   |
 | Day 12: Hill Climbing Algorithm |   🌟   |   🌟   |
 | Day 13: Distress Signal         |   🌟   |   🌟   |
-| Day 14: ???                     |        |        |
+| Day 14: Regolith Reservoir      |   🌟   |   🌟   |
 | Day 15: ???                     |        |        |
 | Day 16: ???                     |        |        |
 | Day 17: ???                     |        |        |
diff --git a/aoc-2022-dotnet/aoc-2022-dotnet.sln b/aoc-2022-dotnet/aoc-2022-dotnet.sln
index cf90abd..fb017eb 100644
--- a/aoc-2022-dotnet/aoc-2022-dotnet.sln
+++ b/aoc-2022-dotnet/aoc-2022-dotnet.sln
@@ -38,7 +38,9 @@ Project("{6EC3EE1D-3C4E-46DD-8F32-0CC8E7565705}") = "Day11", "Day11\Day11.fsproj
 EndProject
 Project("{6EC3EE1D-3C4E-46DD-8F32-0CC8E7565705}") = "Day12", "Day12\Day12.fsproj", "{3A931587-D31B-4ED7-8AB4-D663175AA7B0}"
 EndProject
-Project("{F2A71F9B-5D33-465A-A702-920D77279786}") = "Day13", "Day13\Day13.fsproj", "{60CC1225-2988-48A1-BA37-477053E3CE98}"
+Project("{6EC3EE1D-3C4E-46DD-8F32-0CC8E7565705}") = "Day13", "Day13\Day13.fsproj", "{60CC1225-2988-48A1-BA37-477053E3CE98}"
+EndProject
+Project("{F2A71F9B-5D33-465A-A702-920D77279786}") = "Day14", "Day14\Day14.fsproj", "{3241E7B6-B58B-4032-9746-DF87B1F0D666}"
 EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
@@ -106,6 +108,10 @@ Global
 		{60CC1225-2988-48A1-BA37-477053E3CE98}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{60CC1225-2988-48A1-BA37-477053E3CE98}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{60CC1225-2988-48A1-BA37-477053E3CE98}.Release|Any CPU.Build.0 = Release|Any CPU
+		{3241E7B6-B58B-4032-9746-DF87B1F0D666}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{3241E7B6-B58B-4032-9746-DF87B1F0D666}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{3241E7B6-B58B-4032-9746-DF87B1F0D666}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{3241E7B6-B58B-4032-9746-DF87B1F0D666}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE