Finish day 18

6 files changed, 118 insertions, 5 deletions

diff --git a/aoc-2022-dotnet/Common/Common.fsproj b/aoc-2022-dotnet/Common/Common.fsproj
index 32057cf..510a1ea 100644
--- a/aoc-2022-dotnet/Common/Common.fsproj
+++ b/aoc-2022-dotnet/Common/Common.fsproj
@@ -6,6 +6,7 @@
   </PropertyGroup>
 
   <ItemGroup>
+    <Compile Include="Vec3.fs" />
     <Compile Include="Vec2.fs" />
     <Compile Include="Util.fs" />
   </ItemGroup>
diff --git a/aoc-2022-dotnet/Common/Vec3.fs b/aoc-2022-dotnet/Common/Vec3.fs
new file mode 100644
index 0000000..3a05315
--- /dev/null
+++ b/aoc-2022-dotnet/Common/Vec3.fs
@@ -0,0 +1,33 @@
+namespace Common
+
+type Vec3 =
+    | Vec3 of int * int * int
+
+    static member x(Vec3 (x, _, _)) = x
+    static member y(Vec3 (_, y, _)) = y
+    static member z(Vec3 (_, _, z)) = z
+
+    static member ones = Vec3(1, 1, 1)
+
+    static member directions6 =
+        [ Vec3(-1, 0, 0)
+          Vec3(1, 0, 0)
+          Vec3(0, -1, 0)
+          Vec3(0, 1, 0)
+          Vec3(0, 0, -1)
+          Vec3(0, 0, 1) ]
+
+    static member combine fn (Vec3 (x1, y1, z1)) (Vec3 (x2, y2, z2)) = Vec3(fn x1 x2, fn y1 y2, fn z1 z2)
+
+    static member inline (+)(v1, v2) = Vec3.combine (+) v1 v2
+    static member inline (-)(v1, v2) = Vec3.combine (-) v1 v2
+
+    static member neighbours6 v = List.map ((+) v) Vec3.directions6
+
+    static member boundedBy minBound maxBound (Vec3 (x, y, z)) =
+        x >= Vec3.x minBound
+        && x <= Vec3.x maxBound
+        && y >= Vec3.y minBound
+        && y <= Vec3.y maxBound
+        && z >= Vec3.z minBound
+        && z <= Vec3.z maxBound
diff --git a/aoc-2022-dotnet/Day18/Day18.fsproj b/aoc-2022-dotnet/Day18/Day18.fsproj
new file mode 100644
index 0000000..b9a3919
--- /dev/null
+++ b/aoc-2022-dotnet/Day18/Day18.fsproj
@@ -0,0 +1,22 @@
+<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>
+    <ProjectReference Include="..\Common\Common.fsproj" />
+  </ItemGroup>
+
+</Project>
diff --git a/aoc-2022-dotnet/Day18/Program.fs b/aoc-2022-dotnet/Day18/Program.fs
new file mode 100644
index 0000000..3784d0d
--- /dev/null
+++ b/aoc-2022-dotnet/Day18/Program.fs
@@ -0,0 +1,51 @@
+module Day18
+
+open System.IO
+open FParsec
+open Common
+
+let parsePos =
+    Util.parse (
+        tuple3 (pint32 .>> pchar ',') (pint32 .>> pchar ',') pint32
+        |>> Vec3
+    )
+
+let fullSurface cubes =
+    cubes
+    |> Seq.collect Vec3.neighbours6
+    |> Seq.filter (Util.notIn cubes)
+    |> Seq.length
+
+let externalSurface cubes =
+    let hasLava pos = Set.contains pos cubes
+
+    let minBound = Seq.reduce (Vec3.combine min) cubes - Vec3.ones
+    let maxBound = Seq.reduce (Vec3.combine max) cubes + Vec3.ones
+
+    let neighbours pos =
+        match hasLava pos with
+        | true -> []
+        | false -> List.filter (Vec3.boundedBy minBound maxBound) (Vec3.neighbours6 pos)
+
+    let rec dfs visited count =
+        function
+        | pos :: stackTail ->
+            let count' = count + if hasLava pos then 1 else 0
+
+            match Set.contains pos visited with
+            | true -> dfs visited count' stackTail
+            | false -> dfs (Set.add pos visited) count' (neighbours pos @ stackTail)
+        | [] -> count
+
+    dfs Set.empty 0 [ minBound ]
+
+let solution surface =
+    Seq.map parsePos >> Set.ofSeq >> surface
+
+let test = File.ReadLines("test.txt")
+assert (solution fullSurface test = 64)
+assert (solution externalSurface test = 2540)
+
+let input = File.ReadLines("input.txt")
+printfn "%d" <| solution fullSurface input
+printfn "%d" <| solution externalSurface input
diff --git a/aoc-2022-dotnet/README.md b/aoc-2022-dotnet/README.md
index 25192a0..8d6d1a8 100644
--- a/aoc-2022-dotnet/README.md
+++ b/aoc-2022-dotnet/README.md
@@ -1,6 +1,6 @@
 # Advent of Code 2022 in F#
 ![F#](https://img.shields.io/badge/F%23-grey?logo=.NET)
-![Stars](https://img.shields.io/badge/🌟%20stars-34/50-orange)
+![Stars](https://img.shields.io/badge/🌟%20stars-36/50-orange)
 
 |  Day   | Problem Name                                                     | Part 1 | Part 2 | Practiced Concepts                                   |
 | :----: | ---------------------------------------------------------------- | :----: | :----: | ---------------------------------------------------- |
@@ -12,7 +12,7 @@
 | **06** | [Tuning Trouble](https://adventofcode.com/2022/day/6)            | :star: | :star: | `Seq.windowed`, `Set`                                |
 | **07** | [No Space Left On Device](https://adventofcode.com/2022/day/7)   | :star: | :star: | patterns, ADTs, FParsec                              |
 | **08** | [Treetop Tree House](https://adventofcode.com/2022/day/8)        | :star: | :star: | `Array2D`, slices                                    |
-| **09** | [Rope Bridge](https://adventofcode.com/2022/day/9)               | :star: | :star: | vectors, Chebyshev distance, `Seq.scan`              |
+| **09** | [Rope Bridge](https://adventofcode.com/2022/day/9)               | :star: | :star: | 2D vectors, Chebyshev distance, `Seq.scan`           |
 | **10** | [Cathode-Ray Tube](https://adventofcode.com/2022/day/10)         | :star: | :star: | `Map`, `Seq.fold`                                    |
 | **11** | [Monkey in the Middle](https://adventofcode.com/2022/day/11)     | :star: | :star: | records, type abbrevs, `List.choose`, tail recursion |
 | **12** | [Hill Climbing Algorithm](https://adventofcode.com/2022/day/12)  | :star: | :star: | functional graphs, functional BFS, `Array2D`         |
@@ -21,11 +21,11 @@
 | **15** | [Beacon Exclusion Zone](https://adventofcode.com/2022/day/15)    | :star: | :star: | ranges, mahattan distance, parallel computing        |
 | **16** | [Proboscidea Volcanium](https://adventofcode.com/2022/day/16)    | :star: | :star: | graphs, dynamic programming, `Seq`                   |
 | **17** | [Pyroclastic Flow](https://adventofcode.com/2022/day/17)         | :star: | :star: | cycle detection, bitwise operators, hashing          |
-| **18** | [Boiling Boulders](https://adventofcode.com/2022/day/18)         |        |        |                                                      |
+| **18** | [Boiling Boulders](https://adventofcode.com/2022/day/18)         | :star: | :star: | functional DFS, 3D vectors, position bound checking  |
 | **19** | [Not Enough Minerals](https://adventofcode.com/2022/day/19)      |        |        |                                                      |
 | **20** | [Grove Positioning System](https://adventofcode.com/2022/day/20) |        |        |                                                      |
 | **21** | [Monkey Math](https://adventofcode.com/2022/day/21)              |        |        |                                                      |
-| **22** | ???                                                              |        |        |                                                      |
+| **22** | [Monkey Map](https://adventofcode.com/2022/day/22)               |        |        |                                                      |
 | **23** | ???                                                              |        |        |                                                      |
 | **24** | ???                                                              |        |        |                                                      |
 | **25** | ???                                                              |        |        |                                                      |
diff --git a/aoc-2022-dotnet/aoc-2022-dotnet.sln b/aoc-2022-dotnet/aoc-2022-dotnet.sln
index c8afbfc..32a106b 100644
--- a/aoc-2022-dotnet/aoc-2022-dotnet.sln
+++ b/aoc-2022-dotnet/aoc-2022-dotnet.sln
@@ -46,7 +46,9 @@ Project("{6EC3EE1D-3C4E-46DD-8F32-0CC8E7565705}") = "Day15", "Day15\Day15.fsproj
 EndProject
 Project("{6EC3EE1D-3C4E-46DD-8F32-0CC8E7565705}") = "Day16", "Day16\Day16.fsproj", "{4CABEF49-D9D8-4211-8714-95E118820C8F}"
 EndProject
-Project("{F2A71F9B-5D33-465A-A702-920D77279786}") = "Day17", "Day17\Day17.fsproj", "{7DEA7521-24E1-4ED4-9530-70E91731ADB3}"
+Project("{6EC3EE1D-3C4E-46DD-8F32-0CC8E7565705}") = "Day17", "Day17\Day17.fsproj", "{7DEA7521-24E1-4ED4-9530-70E91731ADB3}"
+EndProject
+Project("{F2A71F9B-5D33-465A-A702-920D77279786}") = "Day18", "Day18\Day18.fsproj", "{31BA1C7C-D4C3-4F57-8129-8EF280911878}"
 EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
@@ -130,6 +132,10 @@ Global
 		{7DEA7521-24E1-4ED4-9530-70E91731ADB3}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{7DEA7521-24E1-4ED4-9530-70E91731ADB3}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{7DEA7521-24E1-4ED4-9530-70E91731ADB3}.Release|Any CPU.Build.0 = Release|Any CPU
+		{31BA1C7C-D4C3-4F57-8129-8EF280911878}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{31BA1C7C-D4C3-4F57-8129-8EF280911878}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{31BA1C7C-D4C3-4F57-8129-8EF280911878}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{31BA1C7C-D4C3-4F57-8129-8EF280911878}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE