Merge branch 'main' into day-18

Co-authored-by: Smaug123 <patrick+github@patrickstevens.co.uk>
Reviewed-on: #20

.gitignore

@@ -10,3 +10,4 @@ result
 .profile*
 
 inputs/
+AdventOfCode2023.FSharp/Test/TestResults/

AdventOfCode2023.FSharp/AdventOfCode2023.FSharp.Bench/AdventOfCode2023.FSharp.Bench.fsproj

@@ -0,0 +1,22 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <OutputType>Exe</OutputType>
+        <TargetFramework>net8.0</TargetFramework>
+    </PropertyGroup>
+
+    <ItemGroup>
+        <Compile Include="Run.fs" />
+        <Compile Include="Inputs.fs" />
+        <Compile Include="Program.fs"/>
+    </ItemGroup>
+
+    <ItemGroup>
+      <PackageReference Include="BenchmarkDotNet" Version="0.13.11" />
+    </ItemGroup>
+
+    <ItemGroup>
+      <ProjectReference Include="..\AdventOfCode2023.FSharp.Lib\AdventOfCode2023.FSharp.Lib.fsproj" />
+    </ItemGroup>
+
+</Project>

AdventOfCode2023.FSharp/AdventOfCode2023.FSharp.Bench/Inputs.fs

@@ -0,0 +1,19 @@
+namespace AdventOfCode2023
+
+open System.IO
+open System.Reflection
+
+[<RequireQualifiedAccess>]
+module Inputs =
+    let days =
+        let mutable dir = Assembly.GetEntryAssembly().Location |> FileInfo |> _.Directory
+
+        while not (dir.EnumerateDirectories () |> Seq.exists (fun i -> i.Name = "inputs")) do
+            dir <- dir.Parent
+
+            if isNull dir then
+                failwith "reached root of filesystem without finding inputs dir"
+
+        Array.init 16 (fun day -> Path.Combine (dir.FullName, "inputs", $"day%i{day + 1}.txt") |> File.ReadAllText)
+
+    let inline day (i : int) = days.[i - 1]

AdventOfCode2023.FSharp/AdventOfCode2023.FSharp.Bench/Program.fs

@@ -0,0 +1,87 @@
+namespace AdventOfCode2023
+
+open BenchmarkDotNet.Attributes
+open BenchmarkDotNet.Configs
+open BenchmarkDotNet.Running
+
+module Benchmarks =
+    type Benchmark1To5 () =
+        [<GlobalSetup>]
+        member _.Setup () = Run.shouldWrite <- false
+
+        [<Params(1, 2, 3, 4, 5)>]
+        member val Day = 0 with get, set
+
+        [<Params(false, true)>]
+        member val IsPartOne = false with get, set
+
+        [<Benchmark>]
+        member this.Benchmark () : unit =
+            Run.allRuns.[this.Day - 1] (not this.IsPartOne) (Inputs.day this.Day)
+
+        [<GlobalCleanup>]
+        member _.Cleanup () = Run.shouldWrite <- true
+
+
+    type Benchmark6To10 () =
+        [<GlobalSetup>]
+        member _.Setup () = Run.shouldWrite <- false
+
+        [<Params(6, 7, 8, 9, 10)>]
+        member val Day = 0 with get, set
+
+        [<Params(false, true)>]
+        member val IsPartOne = false with get, set
+
+        [<Benchmark>]
+        member this.Benchmark () : unit =
+            Run.allRuns.[this.Day - 1] (not this.IsPartOne) (Inputs.day this.Day)
+
+        [<GlobalCleanup>]
+        member _.Cleanup () = Run.shouldWrite <- true
+
+    type Benchmark11To15 () =
+        [<GlobalSetup>]
+        member _.Setup () = Run.shouldWrite <- false
+
+        [<Params(11, 12, 13, 14, 15)>]
+        member val Day = 0 with get, set
+
+        [<Params(false, true)>]
+        member val IsPartOne = false with get, set
+
+        [<Benchmark>]
+        member this.Benchmark () : unit =
+            Run.allRuns.[this.Day - 1] (not this.IsPartOne) (Inputs.day this.Day)
+
+        [<GlobalCleanup>]
+        member _.Cleanup () = Run.shouldWrite <- true
+
+    type Benchmark16To20 () =
+        [<GlobalSetup>]
+        member _.Setup () = Run.shouldWrite <- false
+
+        [<Params(16)>]
+        member val Day = 0 with get, set
+
+        [<Params(false, true)>]
+        member val IsPartOne = false with get, set
+
+        [<Benchmark>]
+        member this.Benchmark () : unit =
+            Run.allRuns.[this.Day - 1] (not this.IsPartOne) (Inputs.day this.Day)
+
+        [<GlobalCleanup>]
+        member _.Cleanup () = Run.shouldWrite <- true
+
+module Program =
+
+    [<EntryPoint>]
+    let main args =
+        let config =
+            ManualConfig.Create(DefaultConfig.Instance).WithOptions ConfigOptions.DisableOptimizationsValidator
+
+        let _summary = BenchmarkRunner.Run<Benchmarks.Benchmark1To5> config
+        let _summary = BenchmarkRunner.Run<Benchmarks.Benchmark6To10> config
+        let _summary = BenchmarkRunner.Run<Benchmarks.Benchmark11To15> config
+        0

AdventOfCode2023.FSharp/AdventOfCode2023.FSharp.Bench/Run.fs

@@ -0,0 +1,242 @@
+namespace AdventOfCode2023
+
+#if DEBUG
+#else
+#nowarn "9"
+#endif
+
+open System
+
+[<RequireQualifiedAccess>]
+module Run =
+    let mutable shouldWrite = true
+
+    let day1 (partTwo : bool) (input : string) =
+        if not partTwo then
+            let output = Day1.part1 input
+
+            if shouldWrite then
+                Console.WriteLine output
+        else
+            let output = Day1.part2 input
+
+            if shouldWrite then
+                Console.WriteLine output
+
+    let day2 (partTwo : bool) (input : string) =
+        if not partTwo then
+            let output = Day2.part1 input
+
+            if shouldWrite then
+                Console.WriteLine output
+        else
+            let output = Day2.part2 input
+
+            if shouldWrite then
+                Console.WriteLine output
+
+    let day3 (partTwo : bool) (input : string) =
+        let resultArr, len, lineCount = Day3.parse (input.ToCharArray () |> Array.map byte)
+#if DEBUG
+        let contents =
+            {
+                Elements = Array.take len resultArr
+                Width = len / lineCount
+            }
+#else
+        use ptr = fixed resultArr
+
+        let contents =
+            {
+                Elements = ptr
+                Length = len
+                Width = len / lineCount
+            }
+#endif
+        if not partTwo then
+            let output = Day3.part1 contents
+
+            if shouldWrite then
+                Console.WriteLine output
+        else
+            let output = Day3.part2 contents
+
+            if shouldWrite then
+                Console.WriteLine output
+
+    let day4 (partTwo : bool) (input : string) =
+        if not partTwo then
+            let output = Day4.part1 input
+
+            if shouldWrite then
+                Console.WriteLine output
+        else
+            let output = Day4.part2 input
+
+            if shouldWrite then
+                Console.WriteLine output
+
+    let day5 (partTwo : bool) (input : string) =
+        if not partTwo then
+            let output = Day5.part1 input
+
+            if shouldWrite then
+                Console.WriteLine output
+        else
+            let output = Day5.part2 input
+
+            if shouldWrite then
+                Console.WriteLine output
+
+    let day6 (partTwo : bool) (input : string) =
+        if not partTwo then
+            let output = Day6.part1 input
+
+            if shouldWrite then
+                Console.WriteLine output
+        else
+            let output = Day6.part2 input
+
+            if shouldWrite then
+                Console.WriteLine output
+
+    let day7 (partTwo : bool) (input : string) =
+        if not partTwo then
+            let output = Day7.part1 input
+
+            if shouldWrite then
+                Console.WriteLine output
+        else
+            let output = Day7.part2 input
+
+            if shouldWrite then
+                Console.WriteLine output
+
+    let day8 (partTwo : bool) (input : string) =
+        if not partTwo then
+            let output = Day8.part1 input
+
+            if shouldWrite then
+                Console.WriteLine output
+        else
+            let output = Day8.part2 input
+
+            if shouldWrite then
+                Console.WriteLine output
+
+    let day9 (partTwo : bool) (input : string) =
+        if not partTwo then
+            let output = Day9.part1 input
+
+            if shouldWrite then
+                Console.WriteLine output
+        else
+            let output = Day9.part2 input
+
+            if shouldWrite then
+                Console.WriteLine output
+
+    let day10 (partTwo : bool) (input : string) =
+        if not partTwo then
+            let output = Day10.part1 input
+
+            if shouldWrite then
+                Console.WriteLine output
+        else
+            let output = Day10.part2 input
+
+            if shouldWrite then
+                Console.WriteLine output
+
+    let day11 (partTwo : bool) (input : string) =
+        if not partTwo then
+            let output = Day11.part1 input
+
+            if shouldWrite then
+                Console.WriteLine output
+        else
+            let output = Day11.part2 input
+
+            if shouldWrite then
+                Console.WriteLine output
+
+
+    let day12 (partTwo : bool) (input : string) =
+        if not partTwo then
+            let output = Day12.part1 input
+
+            if shouldWrite then
+                Console.WriteLine output
+        else
+            let output = Day12.part2 input
+
+            if shouldWrite then
+                Console.WriteLine output
+
+    let day13 (partTwo : bool) (input : string) =
+        if not partTwo then
+            let output = Day13.part1 input
+
+            if shouldWrite then
+                Console.WriteLine output
+        else
+            let output = Day13.part2 input
+
+            if shouldWrite then
+                Console.WriteLine output
+
+    let day14 (partTwo : bool) (input : string) =
+        if not partTwo then
+            let output = Day14.part1 input
+
+            if shouldWrite then
+                Console.WriteLine output
+        else
+            let output = Day14.part2 input
+
+            if shouldWrite then
+                Console.WriteLine output
+
+    let day15 (partTwo : bool) (input : string) =
+        if not partTwo then
+            let output = Day15.part1 input
+
+            if shouldWrite then
+                Console.WriteLine output
+        else
+            let output = Day15.part2 input
+
+            if shouldWrite then
+                Console.WriteLine output
+
+    let day16 (partTwo : bool) (input : string) =
+        if not partTwo then
+            let output = Day16.part1 input
+
+            if shouldWrite then
+                Console.WriteLine output
+        else
+            let output = Day16.part2 input
+
+            if shouldWrite then
+                Console.WriteLine output
+
+    let allRuns =
+        [|
+            day1
+            day2
+            day3
+            day4
+            day5
+            day6
+            day7
+            day8
+            day9
+            day10
+            day11
+            day12
+            day13
+            day14
+            day15
+            day16
+        |]

AdventOfCode2023.FSharp/AdventOfCode2023.FSharp.Lib/AdventOfCode2023.FSharp.Lib.fsproj

@@ -1,23 +1,38 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
-    <PropertyGroup>
-        <TargetFramework>net8.0</TargetFramework>
-        <GenerateDocumentationFile>true</GenerateDocumentationFile>
-    </PropertyGroup>
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <GenerateDocumentationFile>true</GenerateDocumentationFile>
+    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
+  </PropertyGroup>
 
-    <ItemGroup>
-        <Compile Include="Arr2D.fs" />
-        <Compile Include="ResizeArray.fs" />
-        <Compile Include="EfficientString.fs" />
-        <Compile Include="Arithmetic.fs" />
-        <Compile Include="Day1.fs" />
-        <Compile Include="Day2.fs" />
-        <Compile Include="Day3.fs" />
-        <Compile Include="Day4.fs" />
-        <Compile Include="Day5.fs" />
-        <Compile Include="Day6.fs" />
-        <Compile Include="Day7.fs" />
-        <Compile Include="Day8.fs" />
-    </ItemGroup>
+  <ItemGroup>
+    <Compile Include="Arr2D.fs"/>
+    <Compile Include="ResizeArray.fs"/>
+    <Compile Include="EfficientString.fs"/>
+    <Compile Include="Arithmetic.fs"/>
+    <Compile Include="Rational.fs"/>
+    <Compile Include="IntervalSet.fs" />
+    <Compile Include="Direction.fs" />
+    <Compile Include="List.fs" />
+    <Compile Include="Day1.fs"/>
+    <Compile Include="Day2.fs"/>
+    <Compile Include="Day3.fs"/>
+    <Compile Include="Day4.fs"/>
+    <Compile Include="Day5.fs"/>
+    <Compile Include="Day6.fs"/>
+    <Compile Include="Day7.fs"/>
+    <Compile Include="Day8.fs"/>
+    <Compile Include="Day9.fs"/>
+    <Compile Include="Day10.fs" />
+    <Compile Include="Day11.fs" />
+    <Compile Include="Day12.fs" />
+    <Compile Include="Day13.fs" />
+    <Compile Include="Day14.fs" />
+    <Compile Include="Day15.fs" />
+    <Compile Include="Day16.fs" />
+    <Compile Include="Day18.fs" />
+    <Compile Include="Day19.fs" />
+  </ItemGroup>
 
 </Project>

AdventOfCode2023.FSharp/AdventOfCode2023.FSharp.Lib/Arr2D.fs

@@ -5,6 +5,7 @@
 #nowarn "9"
 #endif
 
+open System
 open Microsoft.FSharp.NativeInterop
 
 [<Struct>]
@@ -100,3 +101,76 @@ module Arr2D =
 #else
         NativePtr.initBlock a.Elements 0uy (uint32 sizeof<'a> * uint32 a.Length)
 #endif
+
+    /// Pass in a buffer of memory which we will use entirely for our own purposes (and may resize)
+    /// to maintain state.
+    /// `empty` is the value in empty cells; we will fill them with `fillWith`.
+    let floodFill
+        (stackBuf : ResizeArray<int>)
+        (s : Arr2D<'a>)
+        (empty : 'a)
+        (fillWith : 'a)
+        (currX : int)
+        (currY : int)
+        : unit
+        =
+        stackBuf.Clear ()
+        stackBuf.Add currX
+        stackBuf.Add currY
+
+        while stackBuf.Count > 0 do
+            let currY = stackBuf.[stackBuf.Count - 1]
+            stackBuf.RemoveAt (stackBuf.Count - 1)
+            let currX = stackBuf.[stackBuf.Count - 1]
+            stackBuf.RemoveAt (stackBuf.Count - 1)
+
+            if currX > 0 then
+                if get s (currX - 1) currY = empty then
+                    set s (currX - 1) currY fillWith
+                    stackBuf.Add (currX - 1)
+                    stackBuf.Add currY
+
+            if currX < s.Width - 1 then
+                if get s (currX + 1) currY = empty then
+                    set s (currX + 1) currY fillWith
+                    stackBuf.Add (currX + 1)
+                    stackBuf.Add currY
+
+            if currY > 0 then
+                if get s currX (currY - 1) = empty then
+                    set s currX (currY - 1) fillWith
+                    stackBuf.Add currX
+                    stackBuf.Add (currY - 1)
+
+            if currY < s.Height - 1 then
+                if get s currX (currY + 1) = empty then
+                    set s currX (currY + 1) fillWith
+                    stackBuf.Add currX
+                    stackBuf.Add (currY + 1)
+
+    /// SIMD go brr
+    let inline count< ^a when 'a : equality and 'a : unmanaged and 'a :> IEquatable<'a>>
+        (arr : Arr2D<'a>)
+        (x : 'a)
+        : int
+        =
+        let span =
+#if DEBUG
+            arr.Elements.AsSpan ()
+#else
+            ReadOnlySpan<'a> (NativePtr.toVoidPtr arr.Elements, arr.Length)
+#endif
+        MemoryExtensions.Count (span, x)
+
+    let print (arr : Arr2D<byte>) =
+        for row = 0 to arr.Height - 1 do
+            for col = 0 to arr.Width - 1 do
+                match get arr col row with
+                | 1uy -> printf "#"
+                | 0uy -> printf "."
+                | 2uy -> printf "O"
+                | _ -> failwith "bad"
+
+            printfn ""
+
+        printfn ""

AdventOfCode2023.FSharp/AdventOfCode2023.FSharp.Lib/Day10.fs

@@ -0,0 +1,292 @@
+namespace AdventOfCode2023
+
+#if DEBUG
+#else
+#nowarn "9"
+#endif
+
+open System
+
+[<RequireQualifiedAccess>]
+module Day10 =
+
+    /// Returns first the line number, then the position within that line.
+    /// lineLength includes the newline, as does pos.
+    let inline private toRowAndCol (lineLength : int) (pos : int) : struct (int * int) =
+        let lineNum = pos / lineLength
+        let withinLine = pos % lineLength
+        struct (lineNum, withinLine)
+
+    let inline private ofRowAndCol (lineLength : int) (lineNum : int) (col : int) : int = lineNum * lineLength + col
+
+    let inline nextPoint (s : ReadOnlySpan<char>) (lineLength : int) (currPos : int) (prevPos : int) =
+        let struct (currLineNum, currCol) = toRowAndCol lineLength currPos
+        let struct (prevLineNum, prevCol) = toRowAndCol lineLength prevPos
+
+        match s.[currPos] with
+        | '|' ->
+            if prevLineNum < currLineNum then
+                ofRowAndCol lineLength (currLineNum + 1) currCol
+            else
+                ofRowAndCol lineLength (currLineNum - 1) currCol
+        | '-' ->
+            if prevCol < currCol then
+                ofRowAndCol lineLength currLineNum (currCol + 1)
+            else
+                ofRowAndCol lineLength currLineNum (currCol - 1)
+        | 'L' ->
+            if prevLineNum = currLineNum then
+                ofRowAndCol lineLength (currLineNum - 1) currCol
+            else
+                ofRowAndCol lineLength currLineNum (currCol + 1)
+        | '7' ->
+            if prevLineNum = currLineNum then
+                ofRowAndCol lineLength (currLineNum + 1) currCol
+            else
+                ofRowAndCol lineLength currLineNum (currCol - 1)
+        | 'F' ->
+            if prevLineNum = currLineNum then
+                ofRowAndCol lineLength (currLineNum + 1) currCol
+            else
+                ofRowAndCol lineLength currLineNum (currCol + 1)
+        | 'J' ->
+            if prevLineNum = currLineNum then
+                ofRowAndCol lineLength (currLineNum - 1) currCol
+            else
+                ofRowAndCol lineLength currLineNum (currCol - 1)
+        | c -> failwithf "unrecognised: %c" c
+
+    let part1 (s : string) =
+        let s = s.AsSpan ()
+        let lineLength = (s.IndexOf '\n' + 1)
+        let startPos = s.IndexOf 'S'
+
+        let struct (startLine, startCol) = toRowAndCol lineLength startPos
+        let mutable distance = 1
+        let mutable prevPointA = startPos
+        let mutable prevPointB = startPos
+
+        let mutable pointA =
+            let pos = ofRowAndCol lineLength startLine (startCol - 1)
+
+            match s.[pos] with
+            | '-'
+            | 'L'
+            | 'F' -> pos
+            | _ ->
+
+            let pos = ofRowAndCol lineLength startLine (startCol + 1)
+
+            match s.[pos] with
+            | '-'
+            | 'J'
+            | '7' -> pos
+            | _ ->
+
+            ofRowAndCol lineLength (startLine + 1) startCol
+
+        let mutable pointB =
+            let pos = ofRowAndCol lineLength (startLine - 1) startCol
+
+            match if pos >= 0 then s.[pos] else 'n' with
+            | '|'
+            | '7'
+            | 'F' -> pos
+            | _ ->
+
+            let pos = ofRowAndCol lineLength (startLine + 1) startCol
+
+            match if pos < s.Length then s.[pos] else 'n' with
+            | '|'
+            | 'L'
+            | 'J' -> pos
+            | _ ->
+
+            let pos = ofRowAndCol lineLength startLine (startCol + 1)
+
+            match if pos < s.Length then s.[pos] else 'n' with
+            | '-'
+            | 'J'
+            | '7' -> pos
+            | _ -> ofRowAndCol lineLength startLine (startCol - 1)
+
+        while pointA <> pointB do
+            let currentA = pointA
+            pointA <- nextPoint s lineLength pointA prevPointA
+            prevPointA <- currentA
+
+            let currentB = pointB
+            pointB <- nextPoint s lineLength pointB prevPointB
+            prevPointB <- currentB
+
+            distance <- distance + 1
+
+        distance
+
+    let print (s : Arr2D<byte>) =
+        for y = 0 to s.Height - 1 do
+            for x = 0 to s.Width - 1 do
+                match Arr2D.get s x y with
+                | 0uy -> printf " "
+                | 1uy -> printf "#"
+                | 2uy -> printf "."
+                | s -> failwithf "unrecognised: %i" s
+
+            printfn ""
+
+        printfn ""
+        printfn ""
+
+    let inline setAt (arr : Arr2D<byte>) (x : int) (y : int) (matching : char) (target : byte) =
+        Arr2D.set arr x y target
+
+        match matching with
+        | '-' ->
+            Arr2D.set arr (x - 1) y target
+            Arr2D.set arr (x + 1) y target
+        | '|' ->
+            Arr2D.set arr x (y - 1) target
+            Arr2D.set arr x (y + 1) target
+        | 'L' ->
+            Arr2D.set arr x (y - 1) target
+            Arr2D.set arr (x + 1) y target
+        | 'J' ->
+            Arr2D.set arr x (y - 1) target
+            Arr2D.set arr (x - 1) y target
+        | '7' ->
+            Arr2D.set arr x (y + 1) target
+            Arr2D.set arr (x - 1) y target
+        | 'F' ->
+            Arr2D.set arr x (y + 1) target
+            Arr2D.set arr (x + 1) y target
+        | c -> failwithf "bad char: %c" c
+
+    let part2 (s : string) =
+        let s = s.AsSpan ()
+        let lineCount = s.Count '\n'
+        let lineLength = (s.IndexOf '\n' + 1)
+        let startPos = s.IndexOf 'S'
+
+        let buffer = Array.zeroCreate (lineCount * lineLength * 9)
+#if DEBUG
+        let system : Arr2D<byte> =
+            {
+                Elements = buffer
+                Width = 3 * lineLength
+            }
+#else
+        use ptr = fixed buffer
+
+        let system : Arr2D<byte> =
+            {
+                Elements = ptr
+                Length = buffer.Length
+                Width = 3 * lineLength
+            }
+#endif
+
+        let struct (startLine, startCol) = toRowAndCol lineLength startPos
+        let mutable prevPointA = startPos
+        let mutable prevPointB = startPos
+
+        Arr2D.set system (3 * startCol + 1) (3 * startLine + 1) 1uy
+
+        let mutable pointA =
+            let pos = ofRowAndCol lineLength startLine (startCol - 1)
+
+            match if pos >= 0 then s.[pos] else 'n' with
+            | '-'
+            | 'L'
+            | 'F' ->
+                Arr2D.set system (3 * startCol) (3 * startLine + 1) 1uy
+                pos
+            | _ ->
+
+            let pos = ofRowAndCol lineLength startLine (startCol + 1)
+
+            match if pos < s.Length then s.[pos] else 'n' with
+            | '-'
+            | 'J'
+            | '7' ->
+                Arr2D.set system (3 * startCol + 2) (3 * startLine + 1) 1uy
+                pos
+            | _ ->
+
+            Arr2D.set system (3 * startCol) (3 * startLine) 1uy
+            Arr2D.set system (3 * startCol) (3 * startLine + 2) 1uy
+            ofRowAndCol lineLength (startLine + 1) startCol
+
+        let mutable pointB =
+            let pos = ofRowAndCol lineLength (startLine - 1) startCol
+
+            match if pos >= 0 then s.[pos] else 'n' with
+            | '|'
+            | '7'
+            | 'F' ->
+                Arr2D.set system (3 * startCol + 1) (3 * startLine) 1uy
+                pos
+            | _ ->
+
+            let pos = ofRowAndCol lineLength (startLine + 1) startCol
+
+            match if pos < s.Length then s.[pos] else 'n' with
+            | '|'
+            | 'L'
+            | 'J' ->
+                Arr2D.set system (3 * startCol + 1) (3 * startLine + 2) 1uy
+                pos
+            | _ ->
+
+            let pos = ofRowAndCol lineLength startLine (startCol + 1)
+
+            match if pos < s.Length then s.[pos] else 'n' with
+            | '-'
+            | 'J'
+            | '7' ->
+                Arr2D.set system (3 * startCol + 2) (3 * startLine + 1) 1uy
+                pos
+            | _ -> ofRowAndCol lineLength startLine (startCol - 1)
+
+        do
+            let struct (row, col) = toRowAndCol lineLength pointA
+            setAt system (3 * col + 1) (3 * row + 1) s.[pointA] 1uy
+
+        do
+            let struct (row, col) = toRowAndCol lineLength pointB
+            setAt system (3 * col + 1) (3 * row + 1) s.[pointB] 1uy
+
+        while pointA <> pointB do
+            let currentA = pointA
+            pointA <- nextPoint s lineLength pointA prevPointA
+            prevPointA <- currentA
+
+            do
+                let struct (row, col) = toRowAndCol lineLength pointA
+                setAt system (3 * col + 1) (3 * row + 1) s.[pointA] 1uy
+
+            let currentB = pointB
+            pointB <- nextPoint s lineLength pointB prevPointB
+            prevPointB <- currentB
+
+            do
+                let struct (row, col) = toRowAndCol lineLength pointB
+                setAt system (3 * col + 1) (3 * row + 1) s.[pointB] 1uy
+
+        let stackBuf = ResizeArray ()
+
+        for line = 0 to system.Height - 1 do
+            Arr2D.floodFill stackBuf system 0uy 2uy 0 line
+            Arr2D.floodFill stackBuf system 0uy 2uy (system.Width - 1) line
+
+        for col = 0 to system.Width - 1 do
+            Arr2D.floodFill stackBuf system 0uy 2uy col 0
+            Arr2D.floodFill stackBuf system 0uy 2uy col (system.Height - 1)
+
+        let mutable answer = 0
+
+        for row = 0 to lineCount - 1 do
+            for col = 0 to lineLength - 1 do
+                if Arr2D.get system (3 * col + 1) (3 * row + 1) = 0uy then
+                    answer <- answer + 1
+
+        answer

AdventOfCode2023.FSharp/AdventOfCode2023.FSharp.Lib/Day11.fs

@@ -0,0 +1,93 @@
+namespace AdventOfCode2023
+
+[<RequireQualifiedAccess>]
+module Day11 =
+
+    type Data =
+        {
+            RowsWithoutGalaxies : ResizeArray<int>
+            ColsWithoutGalaxies : ResizeArray<int>
+            /// row * col
+            Galaxies : ResizeArray<int * int>
+        }
+
+    let parse (s : string) : Data =
+        let galaxies = ResizeArray ()
+        let rowsWithoutGalaxies = ResizeArray ()
+        let mutable hasAnyGalaxy = false
+        let mutable currRowIndex = 0
+        let mutable currColIndex = 0
+
+        for c in s do
+            if c = '\n' then
+                if not hasAnyGalaxy then
+                    rowsWithoutGalaxies.Add currRowIndex
+
+                currRowIndex <- currRowIndex + 1
+                currColIndex <- 0
+                hasAnyGalaxy <- false
+            elif c = '#' then
+                hasAnyGalaxy <- true
+                galaxies.Add (currRowIndex, currColIndex)
+                currColIndex <- currColIndex + 1
+            else
+                currColIndex <- currColIndex + 1
+
+        galaxies.Sort (fun (_, c1) (_, c2) -> compare c1 c2)
+
+        let colsWithoutGalaxies =
+            let result = ResizeArray ()
+            let mutable prevCol = 0
+
+            for _, c in galaxies do
+                if c > prevCol then
+                    for j = prevCol + 1 to c - 1 do
+                        result.Add j
+
+                    prevCol <- c
+
+            result
+
+        {
+            RowsWithoutGalaxies = rowsWithoutGalaxies
+            ColsWithoutGalaxies = colsWithoutGalaxies
+            Galaxies = galaxies
+        }
+
+    let solve (data : Data) (expansion : uint64) =
+        let mutable answer = 0uL
+
+        for galaxy1 = 0 to data.Galaxies.Count - 1 do
+            let row1, col1 = data.Galaxies.[galaxy1]
+
+            for galaxy2 = galaxy1 + 1 to data.Galaxies.Count - 1 do
+                let row2, col2 = data.Galaxies.[galaxy2]
+                let baseDistance = uint64 (abs (row1 - row2) + abs (col1 - col2))
+
+                let extraDistance =
+                    let mutable extraDistance = 0uL
+
+                    for i = 1 + min row1 row2 to max row1 row2 - 1 do
+                        if data.RowsWithoutGalaxies.Contains i then
+                            extraDistance <- extraDistance + expansion - 1uL
+
+                    for i = 1 + min col1 col2 to max col1 col2 - 1 do
+                        if data.ColsWithoutGalaxies.Contains i then
+                            extraDistance <- extraDistance + expansion - 1uL
+
+                    extraDistance
+
+                answer <- answer + extraDistance + baseDistance
+
+        answer
+
+
+    let part1 (s : string) =
+        let data = parse s
+
+        solve data 2uL
+
+    let part2 (s : string) =
+        let data = parse s
+
+        solve data 1_000_000uL

AdventOfCode2023.FSharp/AdventOfCode2023.FSharp.Lib/Day12.fs

@@ -0,0 +1,196 @@
+namespace AdventOfCode2023
+
+open System
+open System.Collections.Generic
+open System.Globalization
+
+[<RequireQualifiedAccess>]
+module Day12 =
+
+    let rec solve
+        (dict : Dictionary<int * int, uint64>)
+        (line : ReadOnlySpan<char>)
+        (groups : IReadOnlyList<int>)
+        (remainingToFill : int)
+        (currentGroupIndex : int)
+        : uint64
+        =
+        if line.Length = 0 then
+            if currentGroupIndex = groups.Count then
+                LanguagePrimitives.GenericOne
+            else
+                LanguagePrimitives.GenericZero
+        elif currentGroupIndex = groups.Count then
+            if line.Contains '#' then
+                LanguagePrimitives.GenericZero
+            else
+                LanguagePrimitives.GenericOne
+        else
+
+        match dict.TryGetValue ((line.Length, currentGroupIndex)) with
+        | true, v -> v
+        | false, _ ->
+
+        if remainingToFill > line.Length then
+            dict.Add ((line.Length, currentGroupIndex), LanguagePrimitives.GenericZero)
+            LanguagePrimitives.GenericZero
+        else
+
+        match line.[0] with
+        | '#' ->
+            if currentGroupIndex >= groups.Count then
+                LanguagePrimitives.GenericZero
+            else
+                let mutable isOk = true
+
+                for i = 1 to groups.[currentGroupIndex] - 1 do
+                    if isOk && (i >= line.Length || (line.[i] <> '#' && line.[i] <> '?')) then
+                        isOk <- false
+
+                if not isOk then
+                    LanguagePrimitives.GenericZero
+                else if groups.[currentGroupIndex] < line.Length then
+                    if line.[groups.[currentGroupIndex]] = '#' then
+                        LanguagePrimitives.GenericZero
+                    else
+                        solve
+                            dict
+                            (line.Slice (groups.[currentGroupIndex] + 1))
+                            groups
+                            (remainingToFill - groups.[currentGroupIndex] - 1)
+                            (currentGroupIndex + 1)
+                else
+                    solve
+                        dict
+                        ReadOnlySpan<_>.Empty
+                        groups
+                        (remainingToFill - groups.[currentGroupIndex] - 1)
+                        (currentGroupIndex + 1)
+        | '.' -> solve dict (line.Slice 1) groups remainingToFill currentGroupIndex
+        | '?' ->
+            let afterMark = line.IndexOfAnyExcept ('?', '#')
+
+            if afterMark >= 0 && groups.[currentGroupIndex] > afterMark then
+                // this group would extend into a dot if this were filled in!
+                let firstHash = line.IndexOf '#'
+
+                if firstHash >= 0 && firstHash < afterMark then
+                    // this group *is* filled in, contradiction
+                    LanguagePrimitives.GenericZero
+                else
+                    solve dict (line.Slice afterMark) groups remainingToFill currentGroupIndex
+            else
+
+            let ifDot = solve dict (line.Slice 1) groups remainingToFill currentGroupIndex
+            dict.TryAdd ((line.Length - 1, currentGroupIndex), ifDot) |> ignore
+
+            let ifHash =
+                if currentGroupIndex >= groups.Count then
+                    LanguagePrimitives.GenericZero
+                else
+
+                let mutable isOk = true
+
+                for i = 1 to groups.[currentGroupIndex] - 1 do
+                    if isOk && (i >= line.Length || (line.[i] <> '#' && line.[i] <> '?')) then
+                        isOk <- false
+
+                if not isOk then
+                    LanguagePrimitives.GenericZero
+                else if groups.[currentGroupIndex] < line.Length then
+                    if
+                        groups.[currentGroupIndex] < line.Length
+                        && line.[groups.[currentGroupIndex]] = '#'
+                    then
+                        LanguagePrimitives.GenericZero
+                    else
+                        solve
+                            dict
+                            (line.Slice (groups.[currentGroupIndex] + 1))
+                            groups
+                            (remainingToFill - groups.[currentGroupIndex] - 1)
+                            (currentGroupIndex + 1)
+                else
+                    solve
+                        dict
+                        ReadOnlySpan<_>.Empty
+                        groups
+                        (remainingToFill - groups.[currentGroupIndex] - 1)
+                        (currentGroupIndex + 1)
+
+            let ans = ifDot + ifHash
+            dict.TryAdd ((line.Length, currentGroupIndex), ans) |> ignore
+            ans
+        | _ ->
+            if currentGroupIndex = groups.Count then
+                LanguagePrimitives.GenericOne
+            else
+                LanguagePrimitives.GenericZero
+
+    let part1 (s : string) =
+        use mutable lines = StringSplitEnumerator.make '\n' s
+
+        let mutable answer = 0uL
+        let arr = ResizeArray ()
+
+        let dict = Dictionary ()
+
+        for line in lines do
+            if not line.IsEmpty then
+                arr.Clear ()
+                use ints = StringSplitEnumerator.make' ',' (line.Slice (line.IndexOf ' ' + 1))
+
+                for int in ints do
+                    arr.Add (Int32.Parse (int, NumberStyles.None, CultureInfo.InvariantCulture))
+
+                let remainingToFill =
+                    let mutable ans = -1
+
+                    for i = 0 to arr.Count - 1 do
+                        ans <- ans + arr.[i] + 1
+
+                    ans
+
+                dict.Clear ()
+                let solved = solve dict line arr remainingToFill 0
+                answer <- answer + solved
+
+        answer
+
+    let part2 (s : string) =
+        use mutable lines = StringSplitEnumerator.make '\n' s
+
+        let mutable answer = 0uL
+        let arr = ResizeArray ()
+
+        let dict = Dictionary ()
+
+        for line in lines do
+            if not line.IsEmpty then
+                arr.Clear ()
+                let spaceIndex = line.IndexOf ' '
+
+                for _ = 0 to 4 do
+                    use ints = StringSplitEnumerator.make' ',' (line.Slice (spaceIndex + 1))
+
+                    for int in ints do
+                        arr.Add (Int32.Parse (int, NumberStyles.None, CultureInfo.InvariantCulture))
+
+                let sliced = line.Slice(0, spaceIndex).ToString ()
+
+                let line =
+                    String.Concat (sliced, '?', sliced, '?', sliced, '?', sliced, '?', sliced)
+
+                let remainingToFill =
+                    let mutable ans = -1
+
+                    for i = 0 to arr.Count - 1 do
+                        ans <- ans + arr.[i] + 1
+
+                    ans
+
+                dict.Clear ()
+                let solved = solve dict (line.AsSpan ()) arr remainingToFill 0
+                answer <- answer + solved
+
+        answer

AdventOfCode2023.FSharp/AdventOfCode2023.FSharp.Lib/Day13.fs

@@ -0,0 +1,191 @@
+namespace AdventOfCode2023
+
+open System
+
+[<RequireQualifiedAccess>]
+module Day13 =
+
+    let inline isPowerOf2 (i : uint32) =
+        // https://stackoverflow.com/a/600306/126995
+        (i &&& (i - 1ul)) = 0ul
+
+    let rowToInt (row : ReadOnlySpan<char>) : uint32 =
+        let mutable mult = 1ul
+        let mutable answer = 0ul
+
+        for c = row.Length - 1 downto 0 do
+            if row.[c] = '#' then
+                answer <- answer + mult
+
+            mult <- mult * 2ul
+
+        answer
+
+    let colToInt (grid : ReadOnlySpan<char>) (rowLength : int) (colNum : int) =
+        let mutable mult = 1ul
+        let mutable answer = 0ul
+
+        for i = grid.Count '\n' - 1 downto 0 do
+            if grid.[i * (rowLength + 1) + colNum] = '#' then
+                answer <- answer + mult
+
+            mult <- mult * 2ul
+
+        answer
+
+    let verifyReflection (group : ResizeArray<'a>) (smaller : int) (bigger : int) : bool =
+        let midPoint = (smaller + bigger) / 2
+
+        let rec isOkWithin (curr : int) =
+            if smaller + curr > midPoint then
+                true
+            else if group.[smaller + curr] = group.[bigger - curr] then
+                isOkWithin (curr + 1)
+            else
+                false
+
+        if not (isOkWithin 0) then
+            false
+        else
+
+        smaller = 0 || bigger = group.Count - 1
+
+    /// Find reflection among rows.
+    /// Returns 0 to indicate "no answer".
+    [<TailCall>]
+    let rec findRow (banAnswer : uint32) (rows : ResizeArray<uint32>) (currentLine : int) : uint32 =
+        if currentLine = rows.Count - 1 then
+            0ul
+        else
+            let mutable answer = UInt32.MaxValue
+            let mutable i = currentLine
+
+            while i < rows.Count - 1 do
+                i <- i + 1
+
+                if currentLine % 2 <> i % 2 then
+                    if rows.[i] = rows.[currentLine] then
+                        if verifyReflection rows currentLine i then
+                            let desiredAnswer = uint32 (((currentLine + i) / 2) + 1)
+
+                            if desiredAnswer <> banAnswer then
+                                answer <- uint32 desiredAnswer
+                                i <- Int32.MaxValue
+
+            if answer < UInt32.MaxValue then
+                answer
+            else
+                findRow banAnswer rows (currentLine + 1)
+
+    let render (rowBuf : ResizeArray<_>) (colBuf : ResizeArray<_>) (group : ReadOnlySpan<char>) =
+        rowBuf.Clear ()
+        colBuf.Clear ()
+        let lineLength = group.IndexOf '\n'
+
+        for col = 0 to lineLength - 1 do
+            colBuf.Add (colToInt group lineLength col)
+
+        for row in StringSplitEnumerator.make' '\n' group do
+            if not row.IsEmpty then
+                rowBuf.Add (rowToInt row)
+
+    /// Returns 0 to indicate "no solution".
+    let solve (banAnswer : uint32) (rowBuf : ResizeArray<_>) (colBuf : ResizeArray<_>) : uint32 =
+        match
+            findRow
+                (if banAnswer >= 100ul then
+                     banAnswer / 100ul
+                 else
+                     UInt32.MaxValue)
+                rowBuf
+                0
+        with
+        | rowIndex when rowIndex > 0ul -> 100ul * rowIndex
+        | _ -> findRow banAnswer colBuf 0
+
+    /// Returns also the group with this gro
+    let peelGroup (s : ReadOnlySpan<char>) : ReadOnlySpan<char> =
+        let index = s.IndexOf "\n\n"
+
+        if index < 0 then
+            // last group
+            s
+        else
+            s.Slice (0, index + 1)
+
+    let part1 (s : string) =
+        let mutable s = s.AsSpan ()
+        let rows = ResizeArray ()
+        let cols = ResizeArray ()
+        let mutable answer = 0ul
+
+        while not s.IsEmpty do
+            let group = peelGroup s
+
+            render rows cols group
+            // There's an obvious perf optimisation where we don't compute cols
+            // until we know there's no row answer. Life's too short.
+            answer <- answer + solve UInt32.MaxValue rows cols
+
+            if group.Length >= s.Length then
+                s <- ReadOnlySpan<char>.Empty
+            else
+                s <- s.Slice (group.Length + 1)
+
+        answer
+
+    let flipAt (rows : ResizeArray<_>) (cols : ResizeArray<_>) (rowNum : int) (colNum : int) : unit =
+        rows.[rowNum] <-
+            let index = 1ul <<< (cols.Count - colNum - 1)
+
+            if rows.[rowNum] &&& index > 0ul then
+                rows.[rowNum] - index
+            else
+                rows.[rowNum] + index
+
+        cols.[colNum] <-
+            let index = 1ul <<< (rows.Count - rowNum - 1)
+
+            if cols.[colNum] &&& index > 0ul then
+                cols.[colNum] - index
+            else
+                cols.[colNum] + index
+
+    let part2 (s : string) =
+        let mutable s = s.AsSpan ()
+        let rows = ResizeArray ()
+        let cols = ResizeArray ()
+        let mutable answer = 0ul
+
+        while not s.IsEmpty do
+            let group = peelGroup s
+
+            render rows cols group
+
+            let bannedAnswer = solve UInt32.MaxValue rows cols
+
+            let mutable isDone = false
+            let mutable rowToChange = 0
+
+            while not isDone && rowToChange < rows.Count do
+                let mutable colToChange = 0
+
+                while not isDone && colToChange < cols.Count do
+                    flipAt rows cols rowToChange colToChange
+
+                    match solve bannedAnswer rows cols with
+                    | solved when solved > 0ul ->
+                        isDone <- true
+                        answer <- answer + solved
+                    | _ ->
+                        flipAt rows cols rowToChange colToChange
+                        colToChange <- colToChange + 1
+
+                rowToChange <- rowToChange + 1
+
+            if group.Length >= s.Length then
+                s <- ReadOnlySpan<char>.Empty
+            else
+                s <- s.Slice (group.Length + 1)
+
+        answer

AdventOfCode2023.FSharp/AdventOfCode2023.FSharp.Lib/Day14.fs

@@ -0,0 +1,279 @@
+namespace AdventOfCode2023
+
+#if DEBUG
+#else
+#nowarn "9"
+#endif
+
+open System
+
+[<RequireQualifiedAccess>]
+module Day14 =
+    let slideNorth (arr : Arr2D<byte>) : unit =
+        for col = 0 to arr.Width - 1 do
+            let mutable targetPos = -1
+            let mutable pos = 0
+
+            while targetPos = -1 do
+                if Arr2D.get arr col pos = 0uy then
+                    targetPos <- pos
+
+                pos <- pos + 1
+
+            while pos < arr.Height do
+                let current = Arr2D.get arr col pos
+
+                if current = 2uy then
+                    targetPos <- pos + 1
+                    let mutable hasMoved = false
+
+                    while pos < arr.Height && not hasMoved do
+                        if Arr2D.get arr col pos = 0uy then
+                            targetPos <- pos
+                            hasMoved <- true
+
+                        pos <- pos + 1
+                elif current = 1uy then
+                    Arr2D.set arr col targetPos 1uy
+                    Arr2D.set arr col pos 0uy
+                    targetPos <- targetPos + 1
+                    pos <- pos + 1
+                else // current = 0uy
+                    pos <- pos + 1
+
+    let slideSouth (arr : Arr2D<byte>) : unit =
+        for col = 0 to arr.Width - 1 do
+            let mutable targetPos = arr.Height
+            let mutable pos = arr.Height - 1
+
+            while targetPos = arr.Height do
+                if Arr2D.get arr col pos = 0uy then
+                    targetPos <- pos
+
+                pos <- pos - 1
+
+            while pos >= 0 do
+                let current = Arr2D.get arr col pos
+
+                if current = 2uy then
+                    targetPos <- pos - 1
+                    let mutable hasMoved = false
+
+                    while pos >= 0 && not hasMoved do
+                        if Arr2D.get arr col pos = 0uy then
+                            targetPos <- pos
+                            hasMoved <- true
+
+                        pos <- pos - 1
+                elif current = 1uy then
+                    Arr2D.set arr col targetPos 1uy
+                    Arr2D.set arr col pos 0uy
+                    targetPos <- targetPos - 1
+                    pos <- pos - 1
+                else // current = 0uy
+                    pos <- pos - 1
+
+    let slideEast (arr : Arr2D<byte>) : unit =
+        for row = 0 to arr.Height - 1 do
+            let mutable targetPos = arr.Width
+            let mutable pos = arr.Width - 1
+
+            while targetPos = arr.Width do
+                if Arr2D.get arr pos row = 0uy then
+                    targetPos <- pos
+
+                pos <- pos - 1
+
+            while pos >= 0 do
+                let current = Arr2D.get arr pos row
+
+                if current = 2uy then
+                    targetPos <- pos - 1
+                    let mutable hasMoved = false
+
+                    while pos >= 0 && not hasMoved do
+                        if Arr2D.get arr pos row = 0uy then
+                            targetPos <- pos
+                            hasMoved <- true
+
+                        pos <- pos - 1
+                elif current = 1uy then
+                    Arr2D.set arr targetPos row 1uy
+                    Arr2D.set arr pos row 0uy
+                    targetPos <- targetPos - 1
+                    pos <- pos - 1
+                else // current = 0uy
+                    pos <- pos - 1
+
+    let slideWest (arr : Arr2D<byte>) : unit =
+        for row = 0 to arr.Height - 1 do
+            let mutable targetPos = -1
+            let mutable pos = 0
+
+            while targetPos = -1 do
+                if Arr2D.get arr pos row = 0uy then
+                    targetPos <- pos
+
+                pos <- pos + 1
+
+            while pos < arr.Height do
+                let current = Arr2D.get arr pos row
+
+                if current = 2uy then
+                    targetPos <- pos + 1
+                    let mutable hasMoved = false
+
+                    while pos < arr.Width && not hasMoved do
+                        if Arr2D.get arr pos row = 0uy then
+                            targetPos <- pos
+                            hasMoved <- true
+
+                        pos <- pos + 1
+                elif current = 1uy then
+                    Arr2D.set arr targetPos row 1uy
+                    Arr2D.set arr pos row 0uy
+                    targetPos <- targetPos + 1
+                    pos <- pos + 1
+                else // current = 0uy
+                    pos <- pos + 1
+
+    let score (board : Arr2D<byte>) =
+        let mutable answer = 0ul
+
+        for row = 0 to board.Height - 1 do
+            for col = 0 to board.Width - 1 do
+                if Arr2D.get board col row = 1uy then
+                    answer <- answer + (board.Height - row |> uint32)
+
+        answer
+
+    let hash (board : Arr2D<byte>) =
+        let mutable hash = 0uL
+        let mutable pos = 0uL
+
+        for x = 0 to board.Width - 1 do
+            for y = 0 to board.Height - 1 do
+                hash <- hash + pos * uint64 (Arr2D.get board x y)
+                pos <- pos + 1uL
+
+        hash
+
+    let part1 (s : string) =
+        let s = s.AsSpan ()
+        let lineLength = s.IndexOf '\n'
+
+        let buffer = Array.zeroCreate (lineLength * s.Length / (lineLength + 1))
+        let mutable i = 0
+
+        for c in s do
+            match c with
+            | '#' -> buffer.[i] <- 2uy
+            | '.' -> buffer.[i] <- 0uy
+            | 'O' -> buffer.[i] <- 1uy
+            | '\n' -> i <- i - 1
+            | _ -> failwith "bad char"
+
+            i <- i + 1
+
+#if DEBUG
+        let system : Arr2D<byte> =
+            {
+                Elements = buffer
+                Width = lineLength
+            }
+#else
+        use ptr = fixed buffer
+
+        let system : Arr2D<byte> =
+            {
+                Elements = ptr
+                Length = buffer.Length
+                Width = lineLength
+            }
+#endif
+
+        slideNorth system
+
+        score system
+
+    let cycleOnce (arr : Arr2D<_>) =
+        slideNorth arr
+        slideWest arr
+        slideSouth arr
+        slideEast arr
+
+    let part2 (s : string) =
+        let s = s.AsSpan ()
+        let lineLength = s.IndexOf '\n'
+
+        let buffer = Array.zeroCreate (lineLength * s.Length / (lineLength + 1))
+        let mutable i = 0
+
+        for c in s do
+            match c with
+            | '#' -> buffer.[i] <- 2uy
+            | '.' -> buffer.[i] <- 0uy
+            | 'O' -> buffer.[i] <- 1uy
+            | '\n' -> i <- i - 1
+            | _ -> failwith "bad char"
+
+            i <- i + 1
+
+#if DEBUG
+        let system : Arr2D<byte> =
+            {
+                Elements = buffer
+                Width = lineLength
+            }
+#else
+        use ptr = fixed buffer
+
+        let system : Arr2D<byte> =
+            {
+                Elements = ptr
+                Length = buffer.Length
+                Width = lineLength
+            }
+#endif
+
+        let mutable tortoise = 1
+        let mutable hare = 2
+        let scores = ResizeArray<_> ()
+        scores.Add (score system, hash system)
+        cycleOnce system
+        scores.Add (score system, hash system)
+        cycleOnce system
+        scores.Add (score system, hash system)
+
+        while scores.[hare] <> scores.[tortoise] do
+            cycleOnce system
+            scores.Add (score system, hash system)
+            cycleOnce system
+            scores.Add (score system, hash system)
+
+            hare <- hare + 2
+            tortoise <- tortoise + 1
+
+        tortoise <- 0
+        // mu-table heh heh
+        let mutable firstRepetition = 0
+
+        while scores.[hare] <> scores.[tortoise] do
+            cycleOnce system
+            scores.Add (score system, hash system)
+            hare <- hare + 1
+            tortoise <- tortoise + 1
+            firstRepetition <- firstRepetition + 1
+
+        let mutable cycleLength = 1
+        hare <- tortoise + 1
+
+        while scores.[tortoise] <> scores.[hare] do
+            hare <- hare + 1
+            cycleOnce system
+            scores.Add (score system, hash system)
+            cycleLength <- cycleLength + 1
+
+        let cycles = (1_000_000_000uL - uint64 firstRepetition) % (uint64 cycleLength)
+
+        fst scores.[firstRepetition + int cycles]

AdventOfCode2023.FSharp/AdventOfCode2023.FSharp.Lib/Day15.fs

@@ -0,0 +1,114 @@
+namespace AdventOfCode2023
+
+open System
+open System.Globalization
+
+[<RequireQualifiedAccess>]
+module Day15 =
+
+    let hash (s : ReadOnlySpan<char>) : int =
+        let mutable v = 0
+
+        for c in s do
+            v <- v + int (byte c)
+            v <- (17 * v) % 256
+
+        v
+
+    let part1 (s : string) =
+        let s = s.AsSpan().TrimEnd ()
+        use chunks = StringSplitEnumerator.make' ',' s
+        let mutable answer = 0
+
+        for chunk in chunks do
+            answer <- answer + hash chunk
+
+        answer
+
+    let inline removeFirst<'a> ([<InlineIfLambda>] toRemove : 'a -> bool) (arr : ResizeArray<'a>) : unit =
+        let mutable i = 0
+
+        while i < arr.Count do
+            if toRemove arr.[i] then
+                for j = i to arr.Count - 2 do
+                    arr.[j] <- arr.[j + 1]
+
+                arr.RemoveAt (arr.Count - 1)
+                i <- arr.Count
+
+            i <- i + 1
+
+    let inline replace
+        ([<InlineIfLambda>] withKey : 'a -> 'key)
+        (key : 'key)
+        (value : 'a)
+        (arr : ResizeArray<'a>)
+        : unit
+        =
+        let mutable i = 0
+
+        while i < arr.Count do
+            if withKey arr.[i] = key then
+                arr.[i] <- value
+                i <- arr.Count
+
+            i <- i + 1
+
+        if i < arr.Count + 1 then
+            // no replacement was made
+            arr.Add value
+
+    let inline getLength (labelAndLength : uint64) : uint32 =
+        (labelAndLength % uint64 UInt32.MaxValue) |> uint32
+
+    let inline getLabel (labelAndLength : uint64) : uint32 =
+        (labelAndLength / uint64 UInt32.MaxValue) |> uint32
+
+    let inline focusingPower (boxNumber : uint32) (arr : ResizeArray<_>) =
+        let mutable answer = 0ul
+
+        for i = 0 to arr.Count - 1 do
+            answer <- answer + (boxNumber + 1ul) * (uint32 i + 1ul) * getLength arr.[i]
+
+        answer
+
+    let inline toUint32 (s : ReadOnlySpan<char>) : uint32 =
+        let mutable answer = 0ul
+
+        for c in s do
+            answer <- answer * 26ul + uint32 (byte c - byte 'a')
+
+        answer
+
+    let inline pack (label : uint32) (focalLength : uint32) : uint64 =
+        uint64 label * uint64 UInt32.MaxValue + uint64 focalLength
+
+    let part2 (s : string) =
+        let s = s.AsSpan().TrimEnd ()
+        use chunks = StringSplitEnumerator.make' ',' s
+        // The max length of a label turns out to be 6, which means we need 26^6 < 2^32 entries.
+        // So we'll use a uint32 instead of our string, to save hopping around memory.
+        // We'll also pack the focal length into the elements, to save tupling.
+        let lenses = Array.init 256 (fun _ -> ResizeArray<uint64> ())
+
+        for chunk in chunks do
+            if chunk.[chunk.Length - 1] = '-' then
+                let label = chunk.Slice (0, chunk.Length - 1)
+                let labelShrunk = toUint32 label
+                removeFirst (fun labelAndLength -> getLabel labelAndLength = labelShrunk) lenses.[hash label]
+            else
+                let equalsPos = chunk.IndexOf '='
+
+                let focalLength =
+                    UInt32.Parse (chunk.Slice (equalsPos + 1), NumberStyles.None, CultureInfo.InvariantCulture)
+
+                let label = chunk.Slice (0, equalsPos)
+                let labelShrunk = toUint32 label
+                replace getLabel labelShrunk (pack labelShrunk focalLength) lenses.[hash label]
+
+        let mutable answer = 0ul
+
+        for i = 0 to 255 do
+            answer <- answer + focusingPower (uint32 i) lenses.[i]
+
+        answer

AdventOfCode2023.FSharp/AdventOfCode2023.FSharp.Lib/Day16.fs

@@ -0,0 +1,283 @@
+namespace AdventOfCode2023
+
+#if DEBUG
+#else
+#nowarn "9"
+#endif
+
+open System
+
+[<RequireQualifiedAccess>]
+module Day16 =
+
+    let inline storeDirectionAndPos (numCols : int) (col : int) (row : int) (direction : Direction) : uint16 =
+        4us * uint16 (col + numCols * row) + Direction.toUInt direction
+
+    let inline getDirection (input : uint16) =
+        match input % 4us with
+        | 0us -> Direction.Left
+        | 1us -> Direction.Right
+        | 2us -> Direction.Up
+        | 3us -> Direction.Down
+        | _ -> failwith "bad"
+
+    let inline getCol (numCols : int) (input : uint16) = (input / 4us) % uint16 numCols |> int
+
+    let inline getRow (numCols : int) (input : uint16) = (input / 4us) / uint16 numCols |> int
+
+    let inline maxEncoded (numCols : int) (numRows : int) : uint16 =
+        4us * uint16 ((numCols - 1) + numCols * (numRows - 1)) + 3us
+
+    let inline getAt (numCols : int) (s : string) (row : int) (col : int) = s.[row * (numCols + 1) + col]
+
+    let advance (arr : Arr2D<_>) (going : ResizeArray<_>) (s : string) (nextUp : uint16) =
+        let numCols = arr.Width
+        let numLines = arr.Height
+        let col = getCol numCols nextUp
+        let row = getRow numCols nextUp
+        let dir = getDirection nextUp
+        Arr2D.set arr col row true
+
+        match dir with
+        | Direction.Right ->
+            match getAt numCols s row col with
+            | '-'
+            | '.' ->
+                if col < arr.Width - 1 then
+                    going.[going.Count - 1] <- storeDirectionAndPos numCols (col + 1) row dir
+                else
+                    going.RemoveAt (going.Count - 1)
+            | '/' ->
+                if row > 0 then
+                    going.[going.Count - 1] <- storeDirectionAndPos numCols col (row - 1) Direction.Up
+                else
+                    going.RemoveAt (going.Count - 1)
+            | '\\' ->
+                if row < numLines - 1 then
+                    going.[going.Count - 1] <- storeDirectionAndPos numCols col (row + 1) Direction.Down
+                else
+                    going.RemoveAt (going.Count - 1)
+            | '|' ->
+                going.RemoveAt (going.Count - 1)
+
+                if row < numLines - 1 then
+                    going.Add (storeDirectionAndPos numCols col (row + 1) Direction.Down)
+
+                if row > 0 then
+                    going.Add (storeDirectionAndPos numCols col (row - 1) Direction.Up)
+            | c -> failwith $"Unrecognised char: %c{c}"
+        | Direction.Left ->
+            match getAt numCols s row col with
+            | '-'
+            | '.' ->
+                if col > 0 then
+                    going.[going.Count - 1] <- storeDirectionAndPos numCols (col - 1) row dir
+                else
+                    going.RemoveAt (going.Count - 1)
+            | '\\' ->
+                if row > 0 then
+                    going.[going.Count - 1] <- storeDirectionAndPos numCols col (row - 1) Direction.Up
+                else
+                    going.RemoveAt (going.Count - 1)
+            | '/' ->
+                if row < numLines - 1 then
+                    going.[going.Count - 1] <- storeDirectionAndPos numCols col (row + 1) Direction.Down
+                else
+                    going.RemoveAt (going.Count - 1)
+            | '|' ->
+                going.RemoveAt (going.Count - 1)
+
+                if row < numLines - 1 then
+                    going.Add (storeDirectionAndPos numCols col (row + 1) Direction.Down)
+
+                if row > 0 then
+                    going.Add (storeDirectionAndPos numCols col (row - 1) Direction.Up)
+            | c -> failwith $"Unrecognised char: %c{c}"
+        | Direction.Up ->
+            match getAt numCols s row col with
+            | '|'
+            | '.' ->
+                if row > 0 then
+                    going.[going.Count - 1] <- storeDirectionAndPos numCols col (row - 1) dir
+                else
+                    going.RemoveAt (going.Count - 1)
+            | '/' ->
+                if col < numCols - 1 then
+                    going.[going.Count - 1] <- storeDirectionAndPos numCols (col + 1) row Direction.Right
+                else
+                    going.RemoveAt (going.Count - 1)
+            | '\\' ->
+                if col > 0 then
+                    going.[going.Count - 1] <- storeDirectionAndPos numCols (col - 1) row Direction.Left
+                else
+                    going.RemoveAt (going.Count - 1)
+            | '-' ->
+                going.RemoveAt (going.Count - 1)
+
+                if col < numCols - 1 then
+                    going.Add (storeDirectionAndPos numCols (col + 1) row Direction.Right)
+
+                if col > 0 then
+                    going.Add (storeDirectionAndPos numCols (col - 1) row Direction.Left)
+            | c -> failwith $"Unrecognised char: %c{c}"
+        | Direction.Down ->
+            match getAt numCols s row col with
+            | '|'
+            | '.' ->
+                if row < arr.Height - 1 then
+                    going.[going.Count - 1] <- storeDirectionAndPos numCols col (row + 1) dir
+                else
+                    going.RemoveAt (going.Count - 1)
+            | '\\' ->
+                if col < numCols - 1 then
+                    going.[going.Count - 1] <- storeDirectionAndPos numCols (col + 1) row Direction.Right
+                else
+                    going.RemoveAt (going.Count - 1)
+            | '/' ->
+                if col > 0 then
+                    going.[going.Count - 1] <- storeDirectionAndPos numCols (col - 1) row Direction.Left
+                else
+                    going.RemoveAt (going.Count - 1)
+            | '-' ->
+                going.RemoveAt (going.Count - 1)
+
+                if col < numCols - 1 then
+                    going.Add (storeDirectionAndPos numCols (col + 1) row Direction.Right)
+
+                if col > 0 then
+                    going.Add (storeDirectionAndPos numCols (col - 1) row Direction.Left)
+            | c -> failwith $"Unrecognised char: %c{c}"
+        | _ -> failwith "bad"
+
+    let part1 (s : string) =
+        let numLines = s.AsSpan().Count '\n'
+        let numCols = s.IndexOf '\n'
+        let buf = Array.zeroCreate (numLines * numCols)
+#if DEBUG
+        let arr : Arr2D<bool> =
+            {
+                Elements = buf
+                Width = numCols
+            }
+#else
+        use ptr = fixed buf
+
+        let arr : Arr2D<bool> =
+            {
+                Elements = ptr
+                Width = numCols
+                Length = buf.Length
+            }
+#endif
+        let going = ResizeArray ()
+
+        going.Add (storeDirectionAndPos numCols 0 0 Direction.Right)
+
+        let seen = Array.zeroCreate (int (maxEncoded numCols numLines) + 1)
+
+        while going.Count > 0 do
+            let nextUp = going.[going.Count - 1]
+
+            match seen.[int nextUp] with
+            | true -> going.RemoveAt (going.Count - 1)
+            | false ->
+                seen.[int nextUp] <- true
+                advance arr going s nextUp
+
+        buf.AsSpan().Count true
+
+    let part2 (s : string) =
+        let numLines = s.AsSpan().Count '\n'
+        let numCols = s.IndexOf '\n'
+        let buf = Array.zeroCreate (numLines * numCols)
+#if DEBUG
+        let arr : Arr2D<bool> =
+            {
+                Elements = buf
+                Width = numCols
+            }
+#else
+        use ptr = fixed buf
+
+        let arr : Arr2D<bool> =
+            {
+                Elements = ptr
+                Width = numCols
+                Length = buf.Length
+            }
+#endif
+        let going = ResizeArray ()
+        let seen = Array.zeroCreate (int (maxEncoded numCols numLines) + 1)
+        let mutable best = 0
+
+        for start = 0 to numCols - 1 do
+            going.Clear ()
+            Array.Clear seen
+            Array.Clear buf
+            going.Add (storeDirectionAndPos numCols start 0 Direction.Down)
+
+            while going.Count > 0 do
+                let nextUp = going.[going.Count - 1]
+
+                match seen.[int nextUp] with
+                | true -> going.RemoveAt (going.Count - 1)
+                | false ->
+                    seen.[int nextUp] <- true
+                    advance arr going s nextUp
+
+            let lit = buf.AsSpan().Count true
+            best <- max best lit
+
+            going.Clear ()
+            Array.Clear seen
+            Array.Clear buf
+            going.Add (storeDirectionAndPos numCols start (numLines - 1) Direction.Up)
+
+            while going.Count > 0 do
+                let nextUp = going.[going.Count - 1]
+
+                match seen.[int nextUp] with
+                | true -> going.RemoveAt (going.Count - 1)
+                | false ->
+                    seen.[int nextUp] <- true
+                    advance arr going s nextUp
+
+            let lit = buf.AsSpan().Count true
+            best <- max best lit
+
+        for start = 0 to numLines - 1 do
+            going.Clear ()
+            Array.Clear seen
+            Array.Clear buf
+            going.Add (storeDirectionAndPos numCols 0 start Direction.Right)
+
+            while going.Count > 0 do
+                let nextUp = going.[going.Count - 1]
+
+                match seen.[int nextUp] with
+                | true -> going.RemoveAt (going.Count - 1)
+                | false ->
+                    seen.[int nextUp] <- true
+                    advance arr going s nextUp
+
+            let lit = buf.AsSpan().Count true
+            best <- max best lit
+
+            going.Clear ()
+            Array.Clear seen
+            Array.Clear buf
+            going.Add (storeDirectionAndPos numCols (numCols - 1) start Direction.Left)
+
+            while going.Count > 0 do
+                let nextUp = going.[going.Count - 1]
+
+                match seen.[int nextUp] with
+                | true -> going.RemoveAt (going.Count - 1)
+                | false ->
+                    seen.[int nextUp] <- true
+                    advance arr going s nextUp
+
+            let lit = buf.AsSpan().Count true
+            best <- max best lit
+
+        best

AdventOfCode2023.FSharp/AdventOfCode2023.FSharp.Lib/Day18.fs

@@ -0,0 +1,103 @@
+namespace AdventOfCode2023
+
+#if DEBUG
+#else
+#nowarn "9"
+#endif
+
+open System
+open System.Collections.Generic
+open System.Globalization
+
+[<RequireQualifiedAccess>]
+module Day18 =
+
+    let part1 (s : string) =
+        // Interleaved row and col
+        let mutable weHave = ResizeArray<int> ()
+        weHave.Add 0
+        weHave.Add 0
+
+        let mutable minCol = 0
+        let mutable maxCol = 0
+        let mutable minRow = 0
+        let mutable maxRow = 0
+
+        let mutable col = 0
+        let mutable row = 0
+        let mutable edgeCount = 0
+        use rows = StringSplitEnumerator.make '\n' s
+
+        for currRow in rows do
+            use mutable entries = StringSplitEnumerator.make' ' ' currRow
+            entries.MoveNext () |> ignore
+            let dir = Direction.ofChar entries.Current.[0]
+            entries.MoveNext () |> ignore
+
+            let distance =
+                Int32.Parse (entries.Current, NumberStyles.None, CultureInfo.InvariantCulture)
+
+            edgeCount <- edgeCount + distance
+
+            match dir with
+            | Direction.Down ->
+                for _ = 1 to distance do
+                    row <- row + 1
+                    weHave.Add row
+                    weHave.Add col
+
+                maxRow <- max row maxRow
+            | Direction.Up ->
+                for _ = 1 to distance do
+                    row <- row - 1
+                    weHave.Add row
+                    weHave.Add col
+
+                minRow <- min row minRow
+            | Direction.Left ->
+                for _ = 1 to distance do
+                    col <- col - 1
+                    weHave.Add row
+                    weHave.Add col
+
+                minCol <- min col minCol
+            | Direction.Right ->
+                for _ = 1 to distance do
+                    col <- col + 1
+                    weHave.Add row
+                    weHave.Add col
+
+                maxCol <- max col maxCol
+            | _ -> failwith "bad dir"
+
+        let buffer = Array.zeroCreate ((maxRow - minRow + 3) * (maxCol - minCol + 3))
+#if DEBUG
+        let system : Arr2D<byte> =
+            {
+                Elements = buffer
+                Width = maxCol - minCol + 3
+            }
+#else
+        use ptr = fixed buffer
+
+        let system : Arr2D<byte> =
+            {
+                Elements = ptr
+                Length = buffer.Length
+                Width = maxCol - minCol + 3
+            }
+#endif
+
+        let mutable pointIndex = 0
+
+        while pointIndex < weHave.Count do
+            let row = weHave.[pointIndex]
+            let col = weHave.[pointIndex + 1]
+            Arr2D.set system (col - minCol + 1) (row - minRow + 1) 1uy
+            pointIndex <- pointIndex + 2
+
+        Arr2D.floodFill (ResizeArray ()) system 0uy 2uy 0 0
+
+        Arr2D.count system 0uy + edgeCount
+
+    let part2 (s : string) = -1

AdventOfCode2023.FSharp/AdventOfCode2023.FSharp.Lib/Day19.fs

@@ -0,0 +1,357 @@
+namespace AdventOfCode2023
+
+open System
+open System.Collections.Generic
+open System.Globalization
+
+[<RequireQualifiedAccess>]
+module Day19 =
+
+    type Component =
+        | X = 0
+        | M = 1
+        | A = 2
+        | S = 3
+
+    [<RequireQualifiedAccess>]
+    module Component =
+        let ofChar (c : char) : Component =
+            match c with
+            | 'x' -> Component.X
+            | 'm' -> Component.M
+            | 'a' -> Component.A
+            | 's' -> Component.S
+            | c -> failwith $"bad component: %c{c}"
+
+    type Dest =
+        | Register of string
+        | Accept
+        | Reject
+
+        static member OfString (s : EfficientString) : Dest =
+            if s.Length = 1 && s.[0] = 'A' then Dest.Accept
+            elif s.Length = 1 && s.[0] = 'R' then Dest.Reject
+            else Dest.Register (s.ToString ())
+
+    type Rule =
+        {
+            Component : Component
+            IsLess : bool
+            Operand : int
+            Target : Dest
+        }
+
+        static member OfString (s : EfficientString) : Choice<Rule, Dest> =
+            match s.IndexOf ':' with
+            | -1 -> Choice2Of2 (Dest.OfString (s.Slice (0, s.Length)))
+            | colon ->
+
+            let dest = Dest.OfString (s.Slice (colon + 1))
+            let comp = Component.ofChar s.[0]
+
+            let isLess =
+                match s.[1] with
+                | '>' -> false
+                | '<' -> true
+                | c -> failwith $"Bad comparison: %c{c}"
+
+            let operand =
+                Int32.Parse (s.Slice (2, colon - 2), NumberStyles.None, NumberFormatInfo.InvariantInfo)
+
+            {
+                Component = comp
+                IsLess = isLess
+                Target = dest
+                Operand = operand
+            }
+            |> Choice1Of2
+
+    let inline matches (rule : Rule) x m a s =
+        match rule.Component with
+        | Component.A ->
+            if (rule.IsLess && a < rule.Operand) || (not rule.IsLess && a > rule.Operand) then
+                Some rule.Target
+            else
+                None
+        | Component.X ->
+            if (rule.IsLess && x < rule.Operand) || (not rule.IsLess && x > rule.Operand) then
+                Some rule.Target
+            else
+                None
+        | Component.M ->
+            if (rule.IsLess && m < rule.Operand) || (not rule.IsLess && m > rule.Operand) then
+                Some rule.Target
+            else
+                None
+        | Component.S ->
+            if (rule.IsLess && s < rule.Operand) || (not rule.IsLess && s > rule.Operand) then
+                Some rule.Target
+            else
+                None
+        | _ -> failwith "bad component"
+
+    let rec computePart1 (components : Dictionary<string, Rule ResizeArray * Dest>) x m a s (reg : string) =
+        match components.TryGetValue reg with
+        | false, _ -> failwith $"no rule matched: %s{reg}"
+        | true, (rules, dest) ->
+            let mutable result = ValueNone
+            let mutable i = 0
+
+            while result.IsNone do
+                if i = rules.Count then
+                    result <- ValueSome dest
+                else
+
+                match matches rules.[i] x m a s with
+                | Some dest -> result <- ValueSome dest
+                | None -> i <- i + 1
+
+            match result.Value with
+            | Register reg -> computePart1 components x m a s reg
+            | Accept -> true
+            | Reject -> false
+
+    let readWorkflows (rows : byref<StringSplitEnumerator>) =
+        let workflows = Dictionary<string, Rule ResizeArray * Dest> ()
+
+        while rows.MoveNext () && not rows.Current.IsEmpty do
+            let brace = rows.Current.IndexOf '{'
+            let name = rows.Current.Slice(0, brace).ToString ()
+            let rules = ResizeArray ()
+
+            for rule in StringSplitEnumerator.make' ',' (rows.Current.Slice(brace + 1).TrimEnd '}') do
+                match Rule.OfString rule with
+                | Choice1Of2 rule -> rules.Add rule
+                | Choice2Of2 dest -> workflows.[name] <- (rules, dest)
+
+        workflows
+
+    let part1 (workflows : _) (rows : byref<StringSplitEnumerator>) =
+        let mutable answer = 0
+
+        for row in rows do
+            if not row.IsEmpty then
+                let mutable x = 0
+                let mutable m = 0
+                let mutable a = 0
+                let mutable s = 0
+
+                for comp in StringSplitEnumerator.make' ',' (row.Slice (1, row.Length - 2)) do
+                    let number =
+                        Int32.Parse (comp.Slice 2, NumberStyles.None, NumberFormatInfo.InvariantInfo)
+
+                    match comp.[0] with
+                    | 'x' -> x <- number
+                    | 'm' -> m <- number
+                    | 'a' -> a <- number
+                    | 's' -> s <- number
+                    | c -> failwith $"Bad char: %c{c}"
+
+                if computePart1 workflows x m a s "in" then
+                    answer <- answer + x + m + a + s
+
+        answer
+
+    type AcceptanceCriterion =
+        | True
+        | False
+        | Base of Component * low : int * high : int
+        | And of AcceptanceCriterion * AcceptanceCriterion
+        | Or of AcceptanceCriterion * AcceptanceCriterion
+
+    let rec acAnd a b =
+        match a, b with
+        | AcceptanceCriterion.Or (a1, a2), _ -> AcceptanceCriterion.Or (acAnd a1 b, acAnd a2 b)
+        | AcceptanceCriterion.True, _ -> b
+        | AcceptanceCriterion.False, _ -> False
+        | _, AcceptanceCriterion.Or (b1, b2) -> AcceptanceCriterion.Or (acAnd a b1, acAnd a b2)
+        | _, AcceptanceCriterion.True -> a
+        | _, AcceptanceCriterion.False -> False
+        | _, _ -> AcceptanceCriterion.And (a, b)
+
+    let inline acOr a b =
+        match a, b with
+        | AcceptanceCriterion.False, _ -> b
+        | AcceptanceCriterion.True, _ -> AcceptanceCriterion.True
+        | _, AcceptanceCriterion.False -> a
+        | _, AcceptanceCriterion.True -> AcceptanceCriterion.True
+        | _, _ -> AcceptanceCriterion.Or (a, b)
+
+    /// "low > high" means "empty interval"
+    [<Struct>]
+    type Interval =
+        {
+            Low : int
+            High : int
+        }
+
+        static member Empty =
+            {
+                Low = 1
+                High = 0
+            }
+
+    [<RequireQualifiedAccess>]
+    module Interval =
+        let size (i : Interval) =
+            if i.Low > i.High then 0 else i.High - i.Low + 1
+
+        let intersect (i1 : Interval) (i2 : Interval) =
+            if i1.Low > i1.High || i2.Low > i2.High then
+                i1
+            else if i1.High < i2.Low then
+                Interval.Empty
+            elif i2.High < i1.Low then
+                Interval.Empty
+            else
+                {
+                    Low = max i1.Low i2.Low
+                    High = min i1.High i2.High
+                }
+
+    type Conjunction =
+        {
+            X : Interval
+            M : Interval
+            A : Interval
+            S : Interval
+        }
+
+        static member All =
+            {
+                X =
+                    {
+                        Low = 1
+                        High = 4000
+                    }
+                M =
+                    {
+                        Low = 1
+                        High = 4000
+                    }
+                A =
+                    {
+                        Low = 1
+                        High = 4000
+                    }
+                S =
+                    {
+                        Low = 1
+                        High = 4000
+                    }
+            }
+
+    [<RequireQualifiedAccess>]
+    module Conjunction =
+        let conjAnd (c1 : Conjunction) (c2 : Conjunction) =
+            {
+                X = Interval.intersect c1.X c2.X
+                M = Interval.intersect c1.M c2.M
+                A = Interval.intersect c1.A c2.A
+                S = Interval.intersect c1.S c2.S
+            }
+
+        /// We rely on the intervals being disjoint by construction.
+        let size (x : Conjunction) : uint64 =
+            uint64 (Interval.size x.X)
+            * uint64 (Interval.size x.M)
+            * uint64 (Interval.size x.A)
+            * uint64 (Interval.size x.S)
+
+    type UnionOfConjunctions = Conjunction list
+
+    let rec toUnion (ac : AcceptanceCriterion) : UnionOfConjunctions =
+        match ac with
+        | Base (comp, low, high) ->
+            match comp with
+            | Component.A ->
+                { Conjunction.All with
+                    A =
+                        {
+                            Low = low
+                            High = high
+                        }
+                }
+            | Component.M ->
+                { Conjunction.All with
+                    M =
+                        {
+                            Low = low
+                            High = high
+                        }
+                }
+            | Component.S ->
+                { Conjunction.All with
+                    S =
+                        {
+                            Low = low
+                            High = high
+                        }
+                }
+            | Component.X ->
+                { Conjunction.All with
+                    X =
+                        {
+                            Low = low
+                            High = high
+                        }
+                }
+            | _ -> failwith "bad"
+            |> List.singleton
+        | And (a, b) ->
+            [
+                Conjunction.conjAnd (List.exactlyOne (toUnion a)) (List.exactlyOne (toUnion b))
+            ]
+        | Or (a, b) -> toUnion a @ toUnion b
+        | True -> failwith "already stripped out"
+        | False -> failwith "already stripped out"
+
+    let rec acceptance
+        (store : Dictionary<string, AcceptanceCriterion>)
+        (workflows : Dictionary<string, ResizeArray<Rule> * Dest>)
+        (key : string)
+        : AcceptanceCriterion
+        =
+        match store.TryGetValue key with
+        | true, v -> v
+        | false, _ ->
+
+        let rules, final = workflows.[key]
+
+        let mutable result =
+            match final with
+            | Register s -> acceptance store workflows s
+            | Accept -> AcceptanceCriterion.True
+            | Reject -> AcceptanceCriterion.False
+
+        for i = rules.Count - 1 downto 0 do
+            let rule = rules.[i]
+
+            let cond =
+                if rule.IsLess then
+                    AcceptanceCriterion.Base (rule.Component, 1, rule.Operand - 1)
+                else
+                    AcceptanceCriterion.Base (rule.Component, rule.Operand + 1, 4000)
+
+            let negCond =
+                if rule.IsLess then
+                    AcceptanceCriterion.Base (rule.Component, rule.Operand, 4000)
+                else
+                    AcceptanceCriterion.Base (rule.Component, 1, rule.Operand)
+
+            result <-
+                match rule.Target with
+                | Register target -> acOr (acAnd cond (acceptance store workflows target)) (acAnd negCond result)
+                | Accept -> acOr cond (acAnd negCond result)
+                | Reject -> acAnd negCond result
+
+        store.[key] <- result
+        result
+
+    let part2 (workflows : _) (rows : byref<StringSplitEnumerator>) : uint64 =
+        let acceptanceRanges = Dictionary<string, AcceptanceCriterion> ()
+
+        let a = acceptance acceptanceRanges workflows "in"
+        let union = toUnion a
+
+        union |> List.sumBy Conjunction.size

AdventOfCode2023.FSharp/AdventOfCode2023.FSharp.Lib/Day9.fs

@@ -0,0 +1,55 @@
+namespace AdventOfCode2023
+
+open System
+
+[<RequireQualifiedAccess>]
+module Day9 =
+
+    let extrapolate (isStart : bool) (arr : ResizeArray<int64>) =
+        let mutable answer = 0L
+        let pos = if isStart then -1L else int64 arr.Count
+
+        for i = 0 to arr.Count - 1 do
+            let mutable product = Rational.ofInt arr.[i]
+
+            for j = 0 to arr.Count - 1 do
+                if j <> i then
+                    product <- product * Rational.make (pos - int64 j) (int64 i - int64 j)
+
+            answer <- answer + Rational.assertIntegral product
+
+        answer
+
+    let part1 (s : string) =
+        use s = StringSplitEnumerator.make '\n' s
+        let mutable answer = 0L
+        let arr = ResizeArray ()
+
+        for line in s do
+            arr.Clear ()
+            use line = StringSplitEnumerator.make' ' ' line
+
+            for number in line do
+                let number = Int64.Parse number
+                arr.Add number
+
+            answer <- answer + extrapolate false arr
+
+        answer
+
+    let part2 (s : string) =
+        use s = StringSplitEnumerator.make '\n' s
+        let mutable answer = 0L
+        let arr = ResizeArray ()
+
+        for line in s do
+            arr.Clear ()
+            use line = StringSplitEnumerator.make' ' ' line
+
+            for number in line do
+                let number = Int64.Parse number
+                arr.Add number
+
+            answer <- answer + extrapolate true arr
+
+        answer

AdventOfCode2023.FSharp/AdventOfCode2023.FSharp.Lib/Direction.fs

@@ -0,0 +1,24 @@
+namespace AdventOfCode2023
+
+type Direction =
+    | Left = 0
+    | Right = 1
+    | Up = 2
+    | Down = 3
+
+module Direction =
+    let inline toUInt (d : Direction) =
+        match d with
+        | Direction.Left -> 0us
+        | Direction.Right -> 1us
+        | Direction.Up -> 2us
+        | Direction.Down -> 3us
+        | _ -> failwith "Bad"
+
+    let inline ofChar (c : char) : Direction =
+        match c with
+        | 'L' -> Direction.Left
+        | 'R' -> Direction.Right
+        | 'U' -> Direction.Up
+        | 'D' -> Direction.Down
+        | c -> failwith $"Bad: %c{c}"

AdventOfCode2023.FSharp/AdventOfCode2023.FSharp.Lib/EfficientString.fs

@@ -1,7 +1,6 @@
 namespace AdventOfCode2023
 
 open System
-open System.Globalization
 open System.Runtime.CompilerServices
 
 type EfficientString = System.ReadOnlySpan<char>

AdventOfCode2023.FSharp/AdventOfCode2023.FSharp.Lib/IntervalSet.fs

@@ -0,0 +1,70 @@
+namespace AdventOfCode2023
+
+type IntervalSet = private | IntervalSet of (int * int) list
+
+[<RequireQualifiedAccess>]
+module IntervalSet =
+    let empty = IntervalSet []
+
+    let private add' (low : int) (high : int) intervals : _ list =
+        let rec go (low : int) (high : int) (intervals : (int * int) list) =
+            match intervals with
+            | [] -> [ low, high ]
+            | (lowExisting, highExisting) :: intervals ->
+                if low > highExisting then
+                    (lowExisting, highExisting) :: go low high intervals
+                elif high < lowExisting then
+                    (low, high) :: (lowExisting, highExisting) :: intervals
+                elif high = lowExisting then
+                    (low, highExisting) :: intervals
+                elif high <= highExisting then
+                    (min low lowExisting, highExisting) :: intervals
+                else
+                    // low <= highExisting, highExisting < high
+                    (min low lowExisting, highExisting) :: go (highExisting + 1) high intervals
+
+        go low high intervals
+
+    let add (low : int) (high : int) (IntervalSet intervals) : IntervalSet = add' low high intervals |> IntervalSet
+
+    let contains (x : int) (IntervalSet intervals) : bool =
+        let rec go (intervals : (int * int) list) =
+            match intervals with
+            | [] -> false
+            | (low, high) :: intervals ->
+                if low > x then false
+                elif x <= high then true
+                else go intervals
+
+        go intervals
+
+    let private union' i1 i2 =
+        (i2, i1) ||> List.fold (fun i (low, high) -> add' low high i)
+
+    let union (IntervalSet i1) (IntervalSet i2) : IntervalSet = union' i1 i2 |> IntervalSet
+
+    let private intersectionHelper (low : int) (high : int) (ints : (int * int) list) =
+        let rec go (low : int) (high : int) (ints : (int * int) list) =
+            match ints with
+            | [] -> []
+            | (lowExisting, highExisting) :: ints ->
+                if low > highExisting then
+                    go low high ints
+                elif high < lowExisting then
+                    []
+                elif high <= highExisting then
+                    [ max low lowExisting, high ]
+                else
+                    (max low lowExisting, highExisting) :: go (highExisting + 1) high ints
+
+        go low high ints
+
+    let private intersection' i1 i2 =
+        // a int (b U c) = (a int b) U (a int c)
+        ([], i1)
+        ||> List.fold (fun soFar (low, high) -> union' soFar (intersectionHelper low high i2))
+
+    let intersection (IntervalSet i1) (IntervalSet i2) : IntervalSet = intersection' i1 i2 |> IntervalSet
+
+    let count (IntervalSet i) =
+        i |> List.sumBy (fun (low, high) -> high - low + 1)

AdventOfCode2023.FSharp/AdventOfCode2023.FSharp.Lib/List.fs

@@ -0,0 +1,38 @@
+namespace AdventOfCode2023
+
+open System
+
+[<RequireQualifiedAccess>]
+module List =
+    let rec nTuples (n : int) (xs : 'a list) : 'a list list =
+#if DEBUG
+        if n < 0 then
+            raise (ArgumentException "n cannot be negative")
+#endif
+        match n, xs with
+        | 0, _ -> [ [] ]
+        | _, [] -> []
+        | _, x :: xs ->
+            let withX = nTuples (n - 1) xs |> List.map (fun xs -> x :: xs)
+            let withoutX = nTuples n xs
+            withX @ withoutX
+
+    let inline inclusionExclusion (sizeOf : 'a -> 'ret) (sizeOfTuple : 'a list -> 'ret) (xs : 'a list) : 'ret =
+        let mutable result = List.sumBy sizeOf xs
+        let mutable i = 2
+
+        while i <= xs.Length do
+            let nTuples = nTuples i xs
+            let sum = List.sumBy sizeOfTuple nTuples
+
+            if sum = LanguagePrimitives.GenericZero then
+                i <- Int32.MaxValue
+            else
+                if i % 2 = 0 then
+                    result <- result - sum
+                else
+                    result <- result + sum
+
+                i <- i + 1
+
+        result

AdventOfCode2023.FSharp/AdventOfCode2023.FSharp.Lib/Rational.fs

@@ -0,0 +1,82 @@
+namespace AdventOfCode2023
+
+[<Struct>]
+type Rational<'a
+    when 'a : (static member (+) : 'a * 'a -> 'a)
+    and 'a : (static member (*) : 'a * 'a -> 'a)
+    and 'a : (static member (/) : 'a * 'a -> 'a)
+    and 'a : (static member (-) : 'a * 'a -> 'a)
+    and 'a : (static member Zero : 'a)
+    and 'a : (static member One : 'a)
+    and 'a : comparison> =
+    {
+        Numerator : 'a
+        Denominator : 'a
+    }
+
+    static member inline (+) (a : Rational<'a>, b : Rational<'a>) =
+        let numerator = a.Numerator * b.Denominator + b.Numerator * a.Denominator
+        let denominator = a.Denominator * b.Denominator
+        let hcf = (Arithmetic.euclideanAlgorithm numerator denominator).Hcf
+
+        {
+            Numerator = numerator / hcf
+            Denominator = denominator / hcf
+        }
+
+    static member inline (*) (a : Rational<'a>, b : Rational<'a>) =
+        let numerator = a.Numerator * b.Numerator
+        let denominator = a.Denominator * b.Denominator
+        let hcf = (Arithmetic.euclideanAlgorithm numerator denominator).Hcf
+
+        {
+            Numerator = numerator / hcf
+            Denominator = denominator / hcf
+        }
+
+[<RequireQualifiedAccess>]
+module Rational =
+    let inline ofInt< ^a
+        when 'a : (static member (+) : 'a * 'a -> 'a)
+        and 'a : (static member (*) : 'a * 'a -> 'a)
+        and 'a : (static member (/) : 'a * 'a -> 'a)
+        and 'a : (static member (-) : 'a * 'a -> 'a)
+        and 'a : (static member Zero : 'a)
+        and 'a : (static member One : 'a)
+        and 'a : comparison>
+        (a : 'a)
+        =
+        {
+            Numerator = a
+            Denominator = LanguagePrimitives.GenericOne
+        }
+
+    let inline make< ^a
+        when 'a : (static member (+) : 'a * 'a -> 'a)
+        and 'a : (static member (*) : 'a * 'a -> 'a)
+        and 'a : (static member (/) : 'a * 'a -> 'a)
+        and 'a : (static member (-) : 'a * 'a -> 'a)
+        and 'a : (static member Zero : 'a)
+        and 'a : (static member One : 'a)
+        and 'a : comparison>
+        (numerator : 'a)
+        (denominator : 'a)
+        =
+        let hcf = (Arithmetic.euclideanAlgorithm numerator denominator).Hcf
+
+        {
+            Numerator = numerator / hcf
+            Denominator = denominator / hcf
+        }
+
+    let inline assertIntegral< ^a
+        when 'a : (static member (+) : 'a * 'a -> 'a)
+        and 'a : (static member (*) : 'a * 'a -> 'a)
+        and 'a : (static member (/) : 'a * 'a -> 'a)
+        and 'a : (static member (-) : 'a * 'a -> 'a)
+        and 'a : (static member Zero : 'a)
+        and 'a : (static member One : 'a)
+        and 'a : comparison>
+        (r : Rational<'a>)
+        =
+        r.Numerator

AdventOfCode2023.FSharp/AdventOfCode2023.FSharp.sln

@@ -6,6 +6,8 @@ Project("{F2A71F9B-5D33-465A-A702-920D77279786}") = "Test", "Test\Test.fsproj",
 EndProject
 Project("{F2A71F9B-5D33-465A-A702-920D77279786}") = "AdventOfCode2023.FSharp.Lib", "AdventOfCode2023.FSharp.Lib\AdventOfCode2023.FSharp.Lib.fsproj", "{95CE0568-3D1A-4060-BB54-52460FB1E399}"
 EndProject
+Project("{F2A71F9B-5D33-465A-A702-920D77279786}") = "AdventOfCode2023.FSharp.Bench", "AdventOfCode2023.FSharp.Bench\AdventOfCode2023.FSharp.Bench.fsproj", "{5FD3221D-2C90-4173-8FC0-90553CEE1D4A}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -24,5 +26,9 @@ Global
 		{95CE0568-3D1A-4060-BB54-52460FB1E399}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{95CE0568-3D1A-4060-BB54-52460FB1E399}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{95CE0568-3D1A-4060-BB54-52460FB1E399}.Release|Any CPU.Build.0 = Release|Any CPU
+		{5FD3221D-2C90-4173-8FC0-90553CEE1D4A}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{5FD3221D-2C90-4173-8FC0-90553CEE1D4A}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{5FD3221D-2C90-4173-8FC0-90553CEE1D4A}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{5FD3221D-2C90-4173-8FC0-90553CEE1D4A}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 EndGlobal

AdventOfCode2023.FSharp/AdventOfCode2023.FSharp/AdventOfCode2023.FSharp.fsproj

@@ -1,28 +1,28 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
-    <PropertyGroup>
-        <OutputType>Exe</OutputType>
-        <TargetFramework>net8.0</TargetFramework>
-        <PublishAot>true</PublishAot>
-        <InvariantGlobalization>true</InvariantGlobalization>
-        <UseSystemResourceKeys>true</UseSystemResourceKeys>
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net8.0</TargetFramework>
+    <PublishAot>true</PublishAot>
+    <InvariantGlobalization>true</InvariantGlobalization>
+    <UseSystemResourceKeys>true</UseSystemResourceKeys>
 
-        <IlcOptimizationPreference>Speed</IlcOptimizationPreference>
-        <IlcGenerateStackTraceData>false</IlcGenerateStackTraceData>
+    <IlcOptimizationPreference>Speed</IlcOptimizationPreference>
+    <IlcGenerateStackTraceData>false</IlcGenerateStackTraceData>
 
-        <DebuggerSupport>false</DebuggerSupport>
-        <EnableUnsafeBinaryFormatterSerialization>false</EnableUnsafeBinaryFormatterSerialization>
-        <EventSourceSupport>false</EventSourceSupport>
-        <HttpActivityPropagationSupport>false</HttpActivityPropagationSupport>
-        <MetadataUpdaterSupport>false</MetadataUpdaterSupport>
-    </PropertyGroup>
+    <DebuggerSupport>false</DebuggerSupport>
+    <EnableUnsafeBinaryFormatterSerialization>false</EnableUnsafeBinaryFormatterSerialization>
+    <EventSourceSupport>false</EventSourceSupport>
+    <HttpActivityPropagationSupport>false</HttpActivityPropagationSupport>
+    <MetadataUpdaterSupport>false</MetadataUpdaterSupport>
+  </PropertyGroup>
 
-    <ItemGroup>
-        <Compile Include="Program.fs"/>
-    </ItemGroup>
+  <ItemGroup>
+    <Compile Include="Program.fs"/>
+  </ItemGroup>
 
-    <ItemGroup>
-      <ProjectReference Include="..\AdventOfCode2023.FSharp.Lib\AdventOfCode2023.FSharp.Lib.fsproj" />
-    </ItemGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\AdventOfCode2023.FSharp.Lib\AdventOfCode2023.FSharp.Lib.fsproj"/>
+  </ItemGroup>
 
 </Project>

AdventOfCode2023.FSharp/AdventOfCode2023.FSharp/Program.fs

@@ -179,6 +179,187 @@ module Program =
             Console.WriteLine (part2.ToString ())
             Console.Error.WriteLine ((1_000.0 * float sw.ElapsedTicks / float Stopwatch.Frequency).ToString () + "ms")
 
+        Console.WriteLine "=====Day 9====="
+
+        do
+            let input = Path.Combine (dir.FullName, "day9.txt") |> File.ReadAllText
+
+            sw.Restart ()
+            let part1 = Day9.part1 input
+            sw.Stop ()
+            Console.WriteLine (part1.ToString ())
+            Console.Error.WriteLine ((1_000.0 * float sw.ElapsedTicks / float Stopwatch.Frequency).ToString () + "ms")
+            sw.Restart ()
+            let part2 = Day9.part2 input
+            sw.Stop ()
+            Console.WriteLine (part2.ToString ())
+            Console.Error.WriteLine ((1_000.0 * float sw.ElapsedTicks / float Stopwatch.Frequency).ToString () + "ms")
+
+        Console.WriteLine "=====Day 10====="
+
+        do
+            let input = Path.Combine (dir.FullName, "day10.txt") |> File.ReadAllText
+
+            sw.Restart ()
+            let part1 = Day10.part1 input
+            sw.Stop ()
+            Console.WriteLine (part1.ToString ())
+            Console.Error.WriteLine ((1_000.0 * float sw.ElapsedTicks / float Stopwatch.Frequency).ToString () + "ms")
+            sw.Restart ()
+            let part2 = Day10.part2 input
+            sw.Stop ()
+            Console.WriteLine (part2.ToString ())
+            Console.Error.WriteLine ((1_000.0 * float sw.ElapsedTicks / float Stopwatch.Frequency).ToString () + "ms")
+
+        Console.WriteLine "=====Day 11====="
+
+        do
+            let input = Path.Combine (dir.FullName, "day11.txt") |> File.ReadAllText
+
+            sw.Restart ()
+            let data = Day11.parse input
+            sw.Stop ()
+
+            Console.Error.WriteLine (
+                (1_000.0 * float sw.ElapsedTicks / float Stopwatch.Frequency).ToString ()
+                + "ms parse"
+            )
+
+            sw.Restart ()
+            let part1 = Day11.solve data 2uL
+            sw.Stop ()
+            Console.WriteLine (part1.ToString ())
+            Console.Error.WriteLine ((1_000.0 * float sw.ElapsedTicks / float Stopwatch.Frequency).ToString () + "ms")
+            sw.Restart ()
+            let part2 = Day11.solve data 1_000_000uL
+            sw.Stop ()
+            Console.WriteLine (part2.ToString ())
+            Console.Error.WriteLine ((1_000.0 * float sw.ElapsedTicks / float Stopwatch.Frequency).ToString () + "ms")
+
+        Console.WriteLine "=====Day 12====="
+
+        do
+            let input = Path.Combine (dir.FullName, "day12.txt") |> File.ReadAllText
+
+            sw.Restart ()
+            let part1 = Day12.part1 input
+            sw.Stop ()
+            Console.WriteLine (part1.ToString ())
+            Console.Error.WriteLine ((1_000.0 * float sw.ElapsedTicks / float Stopwatch.Frequency).ToString () + "ms")
+            sw.Restart ()
+            let part2 = Day12.part2 input
+            sw.Stop ()
+            Console.WriteLine (part2.ToString ())
+            Console.Error.WriteLine ((1_000.0 * float sw.ElapsedTicks / float Stopwatch.Frequency).ToString () + "ms")
+
+        Console.WriteLine "=====Day 13====="
+
+        do
+            let input = Path.Combine (dir.FullName, "day13.txt") |> File.ReadAllText
+
+            sw.Restart ()
+            let part1 = Day13.part1 input
+            sw.Stop ()
+            Console.WriteLine (part1.ToString ())
+            Console.Error.WriteLine ((1_000.0 * float sw.ElapsedTicks / float Stopwatch.Frequency).ToString () + "ms")
+            sw.Restart ()
+            let part2 = Day13.part2 input
+            sw.Stop ()
+            Console.WriteLine (part2.ToString ())
+            Console.Error.WriteLine ((1_000.0 * float sw.ElapsedTicks / float Stopwatch.Frequency).ToString () + "ms")
+
+        Console.WriteLine "=====Day 14====="
+
+        do
+            let input = Path.Combine (dir.FullName, "day14.txt") |> File.ReadAllText
+
+            sw.Restart ()
+            let part1 = Day14.part1 input
+            sw.Stop ()
+            Console.WriteLine (part1.ToString ())
+            Console.Error.WriteLine ((1_000.0 * float sw.ElapsedTicks / float Stopwatch.Frequency).ToString () + "ms")
+            sw.Restart ()
+            let part2 = Day14.part2 input
+            sw.Stop ()
+            Console.WriteLine (part2.ToString ())
+            Console.Error.WriteLine ((1_000.0 * float sw.ElapsedTicks / float Stopwatch.Frequency).ToString () + "ms")
+
+        Console.WriteLine "=====Day 15====="
+
+        do
+            let input = Path.Combine (dir.FullName, "day15.txt") |> File.ReadAllText
+
+            sw.Restart ()
+            let part1 = Day15.part1 input
+            sw.Stop ()
+            Console.WriteLine (part1.ToString ())
+            Console.Error.WriteLine ((1_000.0 * float sw.ElapsedTicks / float Stopwatch.Frequency).ToString () + "ms")
+            sw.Restart ()
+            let part2 = Day15.part2 input
+            sw.Stop ()
+            Console.WriteLine (part2.ToString ())
+            Console.Error.WriteLine ((1_000.0 * float sw.ElapsedTicks / float Stopwatch.Frequency).ToString () + "ms")
+
+        Console.WriteLine "=====Day 16====="
+
+        do
+            let input = Path.Combine (dir.FullName, "day16.txt") |> File.ReadAllText
+
+            sw.Restart ()
+            let part1 = Day16.part1 input
+            sw.Stop ()
+            Console.WriteLine (part1.ToString ())
+            Console.Error.WriteLine ((1_000.0 * float sw.ElapsedTicks / float Stopwatch.Frequency).ToString () + "ms")
+            sw.Restart ()
+            let part2 = Day16.part2 input
+            sw.Stop ()
+            Console.WriteLine (part2.ToString ())
+            Console.Error.WriteLine ((1_000.0 * float sw.ElapsedTicks / float Stopwatch.Frequency).ToString () + "ms")
+
+        Console.WriteLine "=====Day 18====="
+
+        do
+            let input = Path.Combine (dir.FullName, "day18.txt") |> File.ReadAllText
+
+            sw.Restart ()
+            let part1 = Day18.part1 input
+            sw.Stop ()
+            Console.WriteLine (part1.ToString ())
+            Console.Error.WriteLine ((1_000.0 * float sw.ElapsedTicks / float Stopwatch.Frequency).ToString () + "ms")
+            sw.Restart ()
+            let part2 = Day18.part2 input
+            sw.Stop ()
+            Console.WriteLine (part2.ToString ())
+            Console.Error.WriteLine ((1_000.0 * float sw.ElapsedTicks / float Stopwatch.Frequency).ToString () + "ms")
+
+        Console.WriteLine "=====Day 19====="
+
+        do
+            let input = Path.Combine (dir.FullName, "day19.txt") |> File.ReadAllText
+
+            sw.Restart ()
+            use mutable s = StringSplitEnumerator.make '\n' input
+            let data = Day19.readWorkflows &s
+            sw.Stop ()
+
+            Console.Error.WriteLine (
+                (1_000.0 * float sw.ElapsedTicks / float Stopwatch.Frequency).ToString ()
+                + "ms parse"
+            )
+
+            let mutable sCopy = s
+
+            sw.Restart ()
+            let part1 = Day19.part1 data &s
+            sw.Stop ()
+            Console.WriteLine (part1.ToString ())
+            Console.Error.WriteLine ((1_000.0 * float sw.ElapsedTicks / float Stopwatch.Frequency).ToString () + "ms")
+            sw.Restart ()
+            let part2 = Day19.part2 data &sCopy
+            sw.Stop ()
+            Console.WriteLine (part2.ToString ())
+            Console.Error.WriteLine ((1_000.0 * float sw.ElapsedTicks / float Stopwatch.Frequency).ToString () + "ms")
+
         endToEnd.Stop ()
 
         Console.Error.WriteLine (

AdventOfCode2023.FSharp/Test/Test.fsproj

@@ -1,44 +1,72 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
-    <PropertyGroup>
-        <TargetFramework>net8.0</TargetFramework>
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
 
-        <IsPackable>false</IsPackable>
-        <IsTestProject>true</IsTestProject>
-    </PropertyGroup>
+    <IsPackable>false</IsPackable>
+    <IsTestProject>true</IsTestProject>
 
-    <ItemGroup>
-        <Compile Include="Util.fs" />
-        <Compile Include="TestDay1.fs" />
-        <Compile Include="TestDay2.fs" />
-        <Compile Include="TestDay3.fs" />
-        <Compile Include="TestDay4.fs" />
-        <Compile Include="TestDay5.fs" />
-        <Compile Include="TestDay6.fs" />
-        <Compile Include="TestDay7.fs" />
-        <Compile Include="TestDay8.fs" />
-        <EmbeddedResource Include="samples\day1.txt" />
-        <EmbeddedResource Include="samples\day1part1.txt" />
-        <EmbeddedResource Include="samples\day2.txt" />
-        <EmbeddedResource Include="samples\day3.txt" />
-        <EmbeddedResource Include="samples\day4.txt" />
-        <EmbeddedResource Include="samples\day5.txt" />
-        <EmbeddedResource Include="samples\day6.txt" />
-        <EmbeddedResource Include="samples\day7.txt" />
-        <EmbeddedResource Include="samples\day8part1.txt" />
-        <EmbeddedResource Include="samples\day8.txt" />
-    </ItemGroup>
+    <EnableStaticNativeInstrumentation>False</EnableStaticNativeInstrumentation>
+    <EnableDynamicNativeInstrumentation>False</EnableDynamicNativeInstrumentation>
+  </PropertyGroup>
 
-    <ItemGroup>
-        <PackageReference Include="FsUnit" Version="5.6.1" />
-        <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.6.0"/>
-        <PackageReference Include="NUnit3TestAdapter" Version="4.2.1"/>
-        <PackageReference Include="NUnit.Analyzers" Version="3.6.1"/>
-        <PackageReference Include="coverlet.collector" Version="6.0.0"/>
-    </ItemGroup>
+  <ItemGroup>
+    <Compile Include="Util.fs"/>
+    <Compile Include="TestIntervalSet.fs" />
+    <Compile Include="TestList.fs" />
+    <Compile Include="TestDay1.fs"/>
+    <Compile Include="TestDay2.fs"/>
+    <Compile Include="TestDay3.fs"/>
+    <Compile Include="TestDay4.fs"/>
+    <Compile Include="TestDay5.fs"/>
+    <Compile Include="TestDay6.fs"/>
+    <Compile Include="TestDay7.fs"/>
+    <Compile Include="TestDay8.fs"/>
+    <Compile Include="TestDay9.fs"/>
+    <Compile Include="TestDay10.fs" />
+    <Compile Include="TestDay11.fs" />
+    <Compile Include="TestDay12.fs" />
+    <Compile Include="TestDay13.fs" />
+    <Compile Include="TestDay14.fs" />
+    <Compile Include="TestDay15.fs" />
+    <Compile Include="TestDay16.fs" />
+    <Compile Include="TestDay18.fs" />
+    <Compile Include="TestDay19.fs" />
+    <EmbeddedResource Include="samples\day1.txt"/>
+    <EmbeddedResource Include="samples\day1part1.txt"/>
+    <EmbeddedResource Include="samples\day2.txt"/>
+    <EmbeddedResource Include="samples\day3.txt"/>
+    <EmbeddedResource Include="samples\day4.txt"/>
+    <EmbeddedResource Include="samples\day5.txt"/>
+    <EmbeddedResource Include="samples\day6.txt"/>
+    <EmbeddedResource Include="samples\day7.txt"/>
+    <EmbeddedResource Include="samples\day8part1.txt"/>
+    <EmbeddedResource Include="samples\day8.txt"/>
+    <EmbeddedResource Include="samples\day9.txt"/>
+    <EmbeddedResource Include="samples\day10part1.txt" />
+    <EmbeddedResource Include="samples\day10.txt" />
+    <EmbeddedResource Include="samples\day11.txt" />
+    <EmbeddedResource Include="samples\day12.txt" />
+    <EmbeddedResource Include="samples\day13.txt" />
+    <EmbeddedResource Include="samples\day14.txt" />
+    <EmbeddedResource Include="samples\day15.txt" />
+    <EmbeddedResource Include="samples\day16.txt" />
+    <EmbeddedResource Include="samples\day18.txt" />
+    <EmbeddedResource Include="samples\day19.txt" />
+  </ItemGroup>
 
-    <ItemGroup>
-      <ProjectReference Include="..\AdventOfCode2023.FSharp.Lib\AdventOfCode2023.FSharp.Lib.fsproj" />
-    </ItemGroup>
+  <ItemGroup>
+    <PackageReference Include="FsCheck" Version="2.16.6" />
+    <PackageReference Include="FsUnit" Version="5.6.1"/>
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0"/>
+    <PackageReference Include="Microsoft.CodeCoverage" Version="17.8.0"/>
+    <PackageReference Include="NUnit3TestAdapter" Version="4.2.1"/>
+    <PackageReference Include="NUnit.Analyzers" Version="3.6.1"/>
+    <PackageReference Include="coverlet.collector" Version="6.0.0"/>
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\AdventOfCode2023.FSharp.Lib\AdventOfCode2023.FSharp.Lib.fsproj"/>
+  </ItemGroup>
 
 </Project>

AdventOfCode2023.FSharp/Test/TestDay10.fs

@@ -0,0 +1,104 @@
+namespace AdventOfCode2023.Test
+
+open AdventOfCode2023
+open NUnit.Framework
+open FsUnitTyped
+open System.IO
+
+[<TestFixture>]
+module TestDay10 =
+
+    let part1Sample1 () =
+        """.....
+.S-7.
+.|.|.
+.L-J.
+.....
+"""
+        |> Day10.part1
+        |> shouldEqual 4
+
+
+    [<Test>]
+    let part1Sample () =
+        Assembly.getEmbeddedResource typeof<Dummy>.Assembly "day10part1.txt"
+        |> Day10.part1
+        |> shouldEqual 8
+
+    [<Test>]
+    let part2Sample1 () =
+        """...........
+.S-------7.
+.|F-----7|.
+.||.....||.
+.||.....||.
+.|L-7.F-J|.
+.|..|.|..|.
+.L--J.L--J.
+...........
+"""
+        |> Day10.part2
+        |> shouldEqual 4
+
+    [<Test>]
+    let part2Sample2 () =
+        """..........
+.S------7.
+.|F----7|.
+.||....||.
+.||....||.
+.|L-7F-J|.
+.|..||..|.
+.L--JL--J.
+..........
+"""
+        |> Day10.part2
+        |> shouldEqual 4
+
+    [<Test>]
+    let part2Sample3 () =
+        """.F----7F7F7F7F-7....
+.|F--7||||||||FJ....
+.||.FJ||||||||L7....
+FJL7L7LJLJ||LJ.L-7..
+L--J.L7...LJS7F-7L7.
+....F-J..F7FJ|L7L7L7
+....L7.F7||L7|.L7L7|
+.....|FJLJ|FJ|F7|.LJ
+....FJL-7.||.||||...
+....L---J.LJ.LJLJ...
+"""
+        |> Day10.part2
+        |> shouldEqual 8
+
+    [<Test>]
+    let part2Sample () =
+        Assembly.getEmbeddedResource typeof<Dummy>.Assembly "day10.txt"
+        |> Day10.part2
+        |> shouldEqual 10
+
+    [<Test>]
+    let part1Actual () =
+        let s =
+            try
+                File.ReadAllText (Path.Combine (__SOURCE_DIRECTORY__, "../../inputs/day10.txt"))
+            with
+            | :? DirectoryNotFoundException
+            | :? FileNotFoundException ->
+                Assert.Inconclusive ()
+                failwith "unreachable"
+
+        Day10.part1 s |> shouldEqual 6842
+
+    [<Test>]
+    let part2Actual () =
+        let s =
+            try
+                File.ReadAllText (Path.Combine (__SOURCE_DIRECTORY__, "../../inputs/day10.txt"))
+            with
+            | :? DirectoryNotFoundException
+            | :? FileNotFoundException ->
+                Assert.Inconclusive ()
+                failwith "unreachable"
+
+        Day10.part2 s |> shouldEqual 393

AdventOfCode2023.FSharp/Test/TestDay11.fs

@@ -0,0 +1,47 @@
+namespace AdventOfCode2023.Test
+
+open AdventOfCode2023
+open NUnit.Framework
+open FsUnitTyped
+open System.IO
+
+[<TestFixture>]
+module TestDay11 =
+
+    let sample = Assembly.getEmbeddedResource typeof<Dummy>.Assembly "day11.txt"
+
+    [<Test>]
+    let part1Sample () =
+        sample |> Day11.part1 |> shouldEqual 374uL
+
+    [<Test>]
+    let part2Sample () =
+        let data = sample |> Day11.parse
+        Day11.solve data 10uL |> shouldEqual 1030uL
+        Day11.solve data 100uL |> shouldEqual 8410uL
+
+    [<Test>]
+    let part1Actual () =
+        let s =
+            try
+                File.ReadAllText (Path.Combine (__SOURCE_DIRECTORY__, "../../inputs/day11.txt"))
+            with
+            | :? DirectoryNotFoundException
+            | :? FileNotFoundException ->
+                Assert.Inconclusive ()
+                failwith "unreachable"
+
+        Day11.part1 s |> shouldEqual 9947476uL
+
+    [<Test>]
+    let part2Actual () =
+        let s =
+            try
+                File.ReadAllText (Path.Combine (__SOURCE_DIRECTORY__, "../../inputs/day11.txt"))
+            with
+            | :? DirectoryNotFoundException
+            | :? FileNotFoundException ->
+                Assert.Inconclusive ()
+                failwith "unreachable"
+
+        Day11.part2 s |> shouldEqual 519939907614uL

AdventOfCode2023.FSharp/Test/TestDay12.fs

@@ -0,0 +1,45 @@
+namespace AdventOfCode2023.Test
+
+open AdventOfCode2023
+open NUnit.Framework
+open FsUnitTyped
+open System.IO
+
+[<TestFixture>]
+module TestDay12 =
+
+    let sample = Assembly.getEmbeddedResource typeof<Dummy>.Assembly "day12.txt"
+
+    [<Test>]
+    let part1Sample () =
+        sample |> Day12.part1 |> shouldEqual 21uL
+
+    [<Test>]
+    let part2Sample () =
+        sample |> Day12.part2 |> shouldEqual 525152uL
+
+    [<Test>]
+    let part1Actual () =
+        let s =
+            try
+                File.ReadAllText (Path.Combine (__SOURCE_DIRECTORY__, "../../inputs/day12.txt"))
+            with
+            | :? DirectoryNotFoundException
+            | :? FileNotFoundException ->
+                Assert.Inconclusive ()
+                failwith "unreachable"
+
+        Day12.part1 s |> shouldEqual 7402uL
+
+    [<Test>]
+    let part2Actual () =
+        let s =
+            try
+                File.ReadAllText (Path.Combine (__SOURCE_DIRECTORY__, "../../inputs/day12.txt"))
+            with
+            | :? DirectoryNotFoundException
+            | :? FileNotFoundException ->
+                Assert.Inconclusive ()
+                failwith "unreachable"
+
+        Day12.part2 s |> shouldEqual 3384337640277uL

AdventOfCode2023.FSharp/Test/TestDay13.fs

@@ -0,0 +1,68 @@
+namespace AdventOfCode2023.Test
+
+open System
+
+open AdventOfCode2023
+open NUnit.Framework
+open FsUnitTyped
+open System.IO
+
+[<TestFixture>]
+module TestDay13 =
+
+    [<Test>]
+    let ``rowToInt test`` () =
+        Day13.rowToInt ("#.##..##.".AsSpan ()) |> shouldEqual 358ul
+
+    [<Test>]
+    let ``colToInt test`` () =
+        let s =
+            """#.##..##.
+..#.##.#.
+##......#
+##......#
+..#.##.#.
+..##..##.
+#.#.##.#.
+"""
+
+        Day13.colToInt (s.AsSpan ()) 9 0
+        |> shouldEqual (List.sum [ 1 ; 8 ; 16 ; 64 ] |> uint32)
+
+    [<Test>]
+
+    let sample = Assembly.getEmbeddedResource typeof<Dummy>.Assembly "day13.txt"
+
+    [<Test>]
+    let part1Sample () =
+        sample |> Day13.part1 |> shouldEqual 405ul
+
+    [<Test>]
+    let part2Sample () =
+        sample |> Day13.part2 |> shouldEqual 400ul
+
+    [<Test>]
+    let part1Actual () =
+        let s =
+            try
+                File.ReadAllText (Path.Combine (__SOURCE_DIRECTORY__, "../../inputs/day13.txt"))
+            with
+            | :? DirectoryNotFoundException
+            | :? FileNotFoundException ->
+                Assert.Inconclusive ()
+                failwith "unreachable"
+
+        Day13.part1 s |> shouldEqual 30158ul
+
+    [<Test>]
+    let part2Actual () =
+        let s =
+            try
+                File.ReadAllText (Path.Combine (__SOURCE_DIRECTORY__, "../../inputs/day13.txt"))
+            with
+            | :? DirectoryNotFoundException
+            | :? FileNotFoundException ->
+                Assert.Inconclusive ()
+                failwith "unreachable"
+
+        Day13.part2 s |> shouldEqual 36474ul

AdventOfCode2023.FSharp/Test/TestDay14.fs

@@ -0,0 +1,48 @@
+namespace AdventOfCode2023.Test
+
+open System
+
+open AdventOfCode2023
+open NUnit.Framework
+open FsUnitTyped
+open System.IO
+
+[<TestFixture>]
+module TestDay14 =
+
+    [<Test>]
+    let sample = Assembly.getEmbeddedResource typeof<Dummy>.Assembly "day14.txt"
+
+    [<Test>]
+    let part1Sample () =
+        sample |> Day14.part1 |> shouldEqual 136ul
+
+    [<Test>]
+    let part2Sample () =
+        sample |> Day14.part2 |> shouldEqual 64ul
+
+    [<Test>]
+    let part1Actual () =
+        let s =
+            try
+                File.ReadAllText (Path.Combine (__SOURCE_DIRECTORY__, "../../inputs/day14.txt"))
+            with
+            | :? DirectoryNotFoundException
+            | :? FileNotFoundException ->
+                Assert.Inconclusive ()
+                failwith "unreachable"
+
+        Day14.part1 s |> shouldEqual 111339ul
+
+    [<Test>]
+    let part2Actual () =
+        let s =
+            try
+                File.ReadAllText (Path.Combine (__SOURCE_DIRECTORY__, "../../inputs/day14.txt"))
+            with
+            | :? DirectoryNotFoundException
+            | :? FileNotFoundException ->
+                Assert.Inconclusive ()
+                failwith "unreachable"
+
+        Day14.part2 s |> shouldEqual 93736ul

AdventOfCode2023.FSharp/Test/TestDay15.fs

@@ -0,0 +1,46 @@
+namespace AdventOfCode2023.Test
+
+open AdventOfCode2023
+open NUnit.Framework
+open FsUnitTyped
+open System.IO
+
+[<TestFixture>]
+module TestDay15 =
+
+    [<Test>]
+    let sample = Assembly.getEmbeddedResource typeof<Dummy>.Assembly "day15.txt"
+
+    [<Test>]
+    let part1Sample () =
+        sample |> Day15.part1 |> shouldEqual 1320
+
+    [<Test>]
+    let part2Sample () =
+        sample |> Day15.part2 |> shouldEqual 145ul
+
+    [<Test>]
+    let part1Actual () =
+        let s =
+            try
+                File.ReadAllText (Path.Combine (__SOURCE_DIRECTORY__, "../../inputs/day15.txt"))
+            with
+            | :? DirectoryNotFoundException
+            | :? FileNotFoundException ->
+                Assert.Inconclusive ()
+                failwith "unreachable"
+
+        Day15.part1 s |> shouldEqual 521434
+
+    [<Test>]
+    let part2Actual () =
+        let s =
+            try
+                File.ReadAllText (Path.Combine (__SOURCE_DIRECTORY__, "../../inputs/day15.txt"))
+            with
+            | :? DirectoryNotFoundException
+            | :? FileNotFoundException ->
+                Assert.Inconclusive ()
+                failwith "unreachable"
+
+        Day15.part2 s |> shouldEqual 248279ul

AdventOfCode2023.FSharp/Test/TestDay16.fs

@@ -0,0 +1,44 @@
+namespace AdventOfCode2023.Test
+
+open AdventOfCode2023
+open NUnit.Framework
+open FsUnitTyped
+open System.IO
+
+[<TestFixture>]
+module TestDay16 =
+
+    [<Test>]
+    let sample = Assembly.getEmbeddedResource typeof<Dummy>.Assembly "day16.txt"
+
+    [<Test>]
+    let part1Sample () = sample |> Day16.part1 |> shouldEqual 46
+
+    [<Test>]
+    let part2Sample () = sample |> Day16.part2 |> shouldEqual 51
+
+    [<Test>]
+    let part1Actual () =
+        let s =
+            try
+                File.ReadAllText (Path.Combine (__SOURCE_DIRECTORY__, "../../inputs/day16.txt"))
+            with
+            | :? DirectoryNotFoundException
+            | :? FileNotFoundException ->
+                Assert.Inconclusive ()
+                failwith "unreachable"
+
+        Day16.part1 s |> shouldEqual 8112
+
+    [<Test>]
+    let part2Actual () =
+        let s =
+            try
+                File.ReadAllText (Path.Combine (__SOURCE_DIRECTORY__, "../../inputs/day16.txt"))
+            with
+            | :? DirectoryNotFoundException
+            | :? FileNotFoundException ->
+                Assert.Inconclusive ()
+                failwith "unreachable"
+
+        Day16.part2 s |> shouldEqual 8314

AdventOfCode2023.FSharp/Test/TestDay18.fs

@@ -0,0 +1,44 @@
+namespace AdventOfCode2023.Test
+
+open AdventOfCode2023
+open NUnit.Framework
+open FsUnitTyped
+open System.IO
+
+[<TestFixture>]
+module TestDay18 =
+
+    [<Test>]
+    let sample = Assembly.getEmbeddedResource typeof<Dummy>.Assembly "day18.txt"
+
+    [<Test>]
+    let part1Sample () = sample |> Day18.part1 |> shouldEqual 62
+
+    [<Test>]
+    let part2Sample () = sample |> Day18.part2 |> shouldEqual 0
+
+    [<Test>]
+    let part1Actual () =
+        let s =
+            try
+                File.ReadAllText (Path.Combine (__SOURCE_DIRECTORY__, "../../inputs/day18.txt"))
+            with
+            | :? DirectoryNotFoundException
+            | :? FileNotFoundException ->
+                Assert.Inconclusive ()
+                failwith "unreachable"
+
+        Day18.part1 s |> shouldEqual 106459
+
+    [<Test>]
+    let part2Actual () =
+        let s =
+            try
+                File.ReadAllText (Path.Combine (__SOURCE_DIRECTORY__, "../../inputs/day18.txt"))
+            with
+            | :? DirectoryNotFoundException
+            | :? FileNotFoundException ->
+                Assert.Inconclusive ()
+                failwith "unreachable"
+
+        Day18.part2 s |> shouldEqual 0

AdventOfCode2023.FSharp/Test/TestDay19.fs

@@ -0,0 +1,55 @@
+namespace AdventOfCode2023.Test
+
+open AdventOfCode2023
+open NUnit.Framework
+open FsUnitTyped
+open System.IO
+
+[<TestFixture>]
+module TestDay19 =
+    [<Test>]
+    let sample = Assembly.getEmbeddedResource typeof<Dummy>.Assembly "day19.txt"
+
+    [<Test>]
+    let part1Sample () =
+        use mutable s = StringSplitEnumerator.make '\n' sample
+        let workflows = Day19.readWorkflows &s
+        Day19.part1 workflows &s |> shouldEqual 19114
+
+    [<Test>]
+    let part2Sample () =
+        use mutable s = StringSplitEnumerator.make '\n' sample
+        let workflows = Day19.readWorkflows &s
+        Day19.part2 workflows &s |> shouldEqual 167409079868000uL
+
+    [<Test>]
+    let part1Actual () =
+        let s =
+            try
+                File.ReadAllText (Path.Combine (__SOURCE_DIRECTORY__, "../../inputs/day19.txt"))
+            with
+            | :? DirectoryNotFoundException
+            | :? FileNotFoundException ->
+                Assert.Inconclusive ()
+                failwith "unreachable"
+
+        use mutable s = StringSplitEnumerator.make '\n' s
+        let workflows = Day19.readWorkflows &s
+
+        Day19.part1 workflows &s |> shouldEqual 368964
+
+    [<Test>]
+    let part2Actual () =
+        let s =
+            try
+                File.ReadAllText (Path.Combine (__SOURCE_DIRECTORY__, "../../inputs/day19.txt"))
+            with
+            | :? DirectoryNotFoundException
+            | :? FileNotFoundException ->
+                Assert.Inconclusive ()
+                failwith "unreachable"
+
+        use mutable s = StringSplitEnumerator.make '\n' s
+        let workflows = Day19.readWorkflows &s
+
+        Day19.part2 workflows &s |> shouldEqual 127675188176682uL

AdventOfCode2023.FSharp/Test/TestDay5.fs

@@ -1,6 +1,5 @@
 namespace AdventOfCode2023.Test
 
-open System
 open AdventOfCode2023
 open NUnit.Framework
 open FsUnitTyped

AdventOfCode2023.FSharp/Test/TestDay6.fs

@@ -1,6 +1,5 @@
 namespace AdventOfCode2023.Test
 
-open System
 open AdventOfCode2023
 open NUnit.Framework
 open FsUnitTyped

AdventOfCode2023.FSharp/Test/TestDay7.fs

@@ -1,6 +1,5 @@
 namespace AdventOfCode2023.Test
 
-open System
 open AdventOfCode2023
 open NUnit.Framework
 open FsUnitTyped

AdventOfCode2023.FSharp/Test/TestDay9.fs

@@ -0,0 +1,44 @@
+namespace AdventOfCode2023.Test
+
+open AdventOfCode2023
+open NUnit.Framework
+open FsUnitTyped
+open System.IO
+
+[<TestFixture>]
+module TestDay9 =
+
+    let sample = Assembly.getEmbeddedResource typeof<Dummy>.Assembly "day9.txt"
+
+    [<Test>]
+    let part1Sample () =
+        sample |> Day9.part1 |> shouldEqual 114L
+
+    [<Test>]
+    let part2Sample () = sample |> Day9.part2 |> shouldEqual 2L
+
+    [<Test>]
+    let part1Actual () =
+        let s =
+            try
+                File.ReadAllText (Path.Combine (__SOURCE_DIRECTORY__, "../../inputs/day9.txt"))
+            with
+            | :? DirectoryNotFoundException
+            | :? FileNotFoundException ->
+                Assert.Inconclusive ()
+                failwith "unreachable"
+
+        Day9.part1 s |> shouldEqual 1898776583L
+
+    [<Test>]
+    let part2Actual () =
+        let s =
+            try
+                File.ReadAllText (Path.Combine (__SOURCE_DIRECTORY__, "../../inputs/day9.txt"))
+            with
+            | :? DirectoryNotFoundException
+            | :? FileNotFoundException ->
+                Assert.Inconclusive ()
+                failwith "unreachable"
+
+        Day9.part2 s |> shouldEqual 1100L

AdventOfCode2023.FSharp/Test/TestIntervalSet.fs

@@ -0,0 +1,86 @@
+namespace AdventOfCode2023.Test
+
+open System.Threading
+open AdventOfCode2023
+open NUnit.Framework
+open FsUnitTyped
+open FsCheck
+
+[<TestFixture>]
+module TestIntervalSet =
+
+    /// Normalises e.g. (5, 3) to (3, 5) too.
+    let toIntervalSet (model : (int * int) list) =
+        (IntervalSet.empty, model)
+        ||> List.fold (fun intervals (x1, x2) -> IntervalSet.add (min x1 x2) (max x1 x2) intervals)
+
+    let modelContains (x : int) (model : (int * int) list) =
+        model
+        |> List.exists (fun (x1, x2) ->
+            let x1, x2 = min x1 x2, max x1 x2
+            x1 <= x && x <= x2
+        )
+
+    [<Test>]
+    let ``IntervalSet add works`` () =
+        let property (pos : int ref) (neg : int ref) (x : int) (xs : (int * int) list) =
+            let intervals = toIntervalSet xs
+
+            let actual = IntervalSet.contains x intervals
+            let expected = modelContains x xs
+
+            if actual then
+                Interlocked.Increment pos |> ignore
+            else
+                Interlocked.Increment neg |> ignore
+
+            expected = actual
+
+        let pos = ref 0
+        let neg = ref 0
+
+        Check.One (
+            { Config.Default with
+                MaxTest = 1000
+            },
+            property pos neg
+        )
+
+        printfn "Fraction of positive cases: %f" ((float pos.Value) / (float pos.Value + float neg.Value))
+
+    [<Test>]
+    let ``Intersection works`` () =
+        let property
+            (pos : int ref)
+            (neg : int ref)
+            (trials : int list)
+            (xsModel : (int * int) list)
+            (ysModel : (int * int) list)
+            =
+            let xs = toIntervalSet xsModel
+            let ys = toIntervalSet ysModel
+
+            let intervals = IntervalSet.intersection xs ys
+
+            for x in trials do
+                let actual = IntervalSet.contains x intervals
+                let expected = modelContains x xsModel && modelContains x ysModel
+
+                expected |> shouldEqual actual
+
+                if actual then
+                    Interlocked.Increment pos |> ignore
+                else
+                    Interlocked.Increment neg |> ignore
+
+        let pos = ref 0
+        let neg = ref 0
+
+        Check.One (
+            { Config.Default with
+                MaxTest = 1000
+            },
+            property pos neg
+        )
+
+        printfn "Fraction of positive cases: %f" ((float pos.Value) / (float pos.Value + float neg.Value))

AdventOfCode2023.FSharp/Test/TestList.fs

@@ -0,0 +1,20 @@
+namespace Test
+
+open NUnit.Framework
+open FsUnitTyped
+open FsCheck
+open AdventOfCode2023
+
+[<TestFixture>]
+module TestList =
+
+    [<Test>]
+    let ``n-tuples have the right length`` () =
+        let property (n : int) (xs : char list) =
+            let n = min (abs n) 6
+            let xs = xs |> List.take (min 10 xs.Length)
+            let tuples = List.nTuples n xs
+            tuples |> List.forall (fun i -> i.Length = n)
+
+        property 1 [ 'v' ] |> shouldEqual true
+        Check.QuickThrowOnFailure property

AdventOfCode2023.FSharp/Test/samples/day10.txt

@@ -0,0 +1,10 @@
+FF7FSF7F7F7F7F7F---7
+L|LJ||||||||||||F--J
+FL-7LJLJ||||||LJL-77
+F--JF--7||LJLJ7F7FJ-
+L---JF-JLJ.||-FJLJJ7
+|F|F-JF---7F7-L7L|7|
+|FFJF7L7F-JF7|JL---7
+7-L-JL7||F7|L7F-7F7|
+L.L7LFJ|||||FJL7||LJ
+L7JLJL-JLJLJL--JLJ.L

AdventOfCode2023.FSharp/Test/samples/day10part1.txt

@@ -0,0 +1,5 @@
+..F7.
+.FJ|.
+SJ.L7
+|F--J
+LJ...

AdventOfCode2023.FSharp/Test/samples/day11.txt

@@ -0,0 +1,10 @@
+...#......
+.......#..
+#.........
+..........
+......#...
+.#........
+.........#
+..........
+.......#..
+#...#.....

AdventOfCode2023.FSharp/Test/samples/day12.txt

@@ -0,0 +1,6 @@
+???.### 1,1,3
+.??..??...?##. 1,1,3
+?#?#?#?#?#?#?#? 1,3,1,6
+????.#...#... 4,1,1
+????.######..#####. 1,6,5
+?###???????? 3,2,1

AdventOfCode2023.FSharp/Test/samples/day13.txt

@@ -0,0 +1,15 @@
+#.##..##.
+..#.##.#.
+##......#
+##......#
+..#.##.#.
+..##..##.
+#.#.##.#.
+
+#...##..#
+#....#..#
+..##..###
+#####.##.
+#####.##.
+..##..###
+#....#..#

AdventOfCode2023.FSharp/Test/samples/day14.txt

@@ -0,0 +1,10 @@
+O....#....
+O.OO#....#
+.....##...
+OO.#O....O
+.O.....O#.
+O.#..O.#.#
+..O..#O..O
+.......O..
+#....###..
+#OO..#....

AdventOfCode2023.FSharp/Test/samples/day15.txt

@@ -0,0 +1 @@
+rn=1,cm-,qp=3,cm=2,qp-,pc=4,ot=9,ab=5,pc-,pc=6,ot=7

AdventOfCode2023.FSharp/Test/samples/day16.txt

@@ -0,0 +1,10 @@
+.|...\....
+|.-.\.....
+.....|-...
+........|.
+..........
+.........\
+..../.\\..
+.-.-/..|..
+.|....-|.\
+..//.|....

AdventOfCode2023.FSharp/Test/samples/day18.txt

@@ -0,0 +1,14 @@
+R 6 (#70c710)
+D 5 (#0dc571)
+L 2 (#5713f0)
+D 2 (#d2c081)
+R 2 (#59c680)
+D 2 (#411b91)
+L 5 (#8ceee2)
+U 2 (#caa173)
+L 1 (#1b58a2)
+U 2 (#caa171)
+R 2 (#7807d2)
+U 3 (#a77fa3)
+L 2 (#015232)
+U 2 (#7a21e3)

AdventOfCode2023.FSharp/Test/samples/day19.txt

@@ -0,0 +1,17 @@
+px{a<2006:qkq,m>2090:A,rfg}
+pv{a>1716:R,A}
+lnx{m>1548:A,A}
+rfg{s<537:gd,x>2440:R,A}
+qs{s>3448:A,lnx}
+qkq{x<1416:A,crn}
+crn{x>2662:A,R}
+in{s<1351:px,qqz}
+qqz{s>2770:qs,m<1801:hdj,R}
+gd{a>3333:R,R}
+hdj{m>838:A,pv}
+
+{x=787,m=2655,a=1222,s=2876}
+{x=1679,m=44,a=2067,s=496}
+{x=2036,m=264,a=79,s=2244}
+{x=2461,m=1339,a=466,s=291}
+{x=2127,m=1623,a=2188,s=1013}

AdventOfCode2023.FSharp/Test/samples/day9.txt

@@ -0,0 +1,3 @@
+0 3 6 9 12 15
+1 3 6 10 15 21
+10 13 16 21 30 45

README.md

@@ -7,23 +7,109 @@
 Ahead-of-time compiled with `PublishAot`, M1 Max.
 The format is: "answer part1\ntime\nanswer part2\ntime\n...", with possible extra lines indicating how long it took to parse the input if I happen to have split that out.
 
-After day 3:
+BenchmarkDotNet:
 
 ```
+| Day | IsPartOne | Mean      | Error    | StdDev   |
+|---- |---------- |----------:|---------:|---------:|
+| 1   | True      |  10.23 us | 0.036 us | 0.032 us |
+| 1   | False     |  17.93 us | 0.203 us | 0.180 us |
+| 2   | True      |  17.39 us | 0.080 us | 0.075 us |
+| 2   | False     |  25.42 us | 0.155 us | 0.145 us |
+| 3   | True      |  65.60 us | 0.393 us | 0.328 us |
+| 3   | False     | 145.52 us | 0.256 us | 0.200 us |
+| 4   | True      | 109.78 us | 0.236 us | 0.209 us |
+| 4   | False     | 110.34 us | 0.081 us | 0.063 us |
+| 5   | True      |  13.44 us | 0.045 us | 0.042 us |
+| 5   | False     |  61.70 us | 0.199 us | 0.177 us |
+
+| Day | IsPartOne | Mean           | Error       | StdDev      |
+|---- |---------- |---------------:|------------:|------------:|
+| 6   | True      |       314.7 ns |     1.87 ns |     1.65 ns |
+| 6   | False     |       316.3 ns |     0.31 ns |     0.26 ns |
+| 7   | True      |    89,256.3 ns |   578.24 ns |   540.88 ns |
+| 7   | False     |    95,062.7 ns |   921.75 ns |   862.21 ns |
+| 8   | True      |   423,461.0 ns | 7,218.95 ns | 6,752.61 ns |
+| 8   | False     | 2,045,302.1 ns | 4,338.61 ns | 3,846.06 ns |
+| 9   | True      | 1,390,976.2 ns | 2,171.39 ns | 1,813.21 ns |
+| 9   | False     | 2,173,468.1 ns | 3,171.04 ns | 2,647.96 ns |
+| 10  | True      |    57,460.7 ns | 1,135.45 ns | 2,160.31 ns |
+| 10  | False     |   694,553.9 ns | 2,935.74 ns | 2,746.09 ns |
+
+| Day | IsPartOne | Mean      | Error     | StdDev    | Median    |
+|---- |---------- |----------:|----------:|----------:|----------:|
+| 11  | True      | 39.085 ms | 0.0355 ms | 0.0297 ms | 39.082 ms |
+| 11  | False     | 38.608 ms | 0.0270 ms | 0.0211 ms | 38.617 ms |
+| 12  | True      |  1.846 ms | 0.0044 ms | 0.0041 ms |  1.845 ms |
+| 12  | False     | 18.692 ms | 0.3676 ms | 0.3775 ms | 18.962 ms |
+```
+
+After day 12, a single run of the ahead-of-time compiled version:
+
+```
+=====Day 1=====
 54304
-0.549458ms
+3.418417ms
 54418
-0.710375ms
+0.317958ms
+=====Day 2=====
 2727
-0.119959ms
+0.079917ms
 56580
-0.155708ms
-0.1395ms parse
+0.107292ms
+=====Day 3=====
+0.140292ms parse
 540131
-0.1395ms
+0.140292ms
 86879020
-0.840791ms
-4.144166ms total
+0.664416ms
+=====Day 4=====
+27454
+0.390541ms
+6857330
+0.360375ms
+=====Day 5=====
+806029445
+0.161917ms
+59370572
+0.249708ms
+=====Day 6=====
+32076
+0.002917ms
+34278221
+0.001667ms
+=====Day 7=====
+250058342
+0.409792ms
+250506580
+0.431167ms
+=====Day 8=====
+19199
+1.192792ms
+13663968099527
+5.276083ms
+=====Day 9=====
+1898776583
+3.775667ms
+1100
+5.365875ms
+=====Day 10=====
+6842
+0.201208ms
+393
+2.226042ms
+=====Day 11=====
+0.11225ms parse
+9947476
+48.423ms
+519939907614
+34.836125ms
+=====Day 12=====
+7402
+4.704375ms
+3384337640277
+31.825583ms
+151.644334ms total
 ```
 
 # Building yourself

mathematica/day_21.m

@@ -0,0 +1,30 @@
+(* ::Package:: *)
+
+(* ::Input:: *)
+(*s="...........*)
+(*.....###.#.*)
+(*.###.##..#.*)
+(*..#.#...#..*)
+(*....#.#....*)
+(*.##..S####.*)
+(*.##..#...#.*)
+(*.......##..*)
+(*.##.#.####.*)
+(*.##..##.##.*)
+(*...........";*)
+
+
+(* ::Input:: *)
+(*reachable[grid_,{row_Integer,col_Integer}]:=reachable[grid,{row,col}]=Select[{{row+1,col},{row-1,col},{row,col+1},{row,col-1}},*)
+(*1<=#[[1]]<=Length[grid]&&1<=#[[2]]<=Length[First@grid]&&grid[[#[[1]],#[[2]]]]!="#"&*)
+(*]*)
+
+
+(* ::Input:: *)
+(*f[grid_,pos_,0]:={pos}*)
+(*f[grid_,pos_,timestepsRemaining_Integer]:=*)
+(*f[grid,pos,timestepsRemaining]=DeleteDuplicates@Flatten[f[grid,#,timestepsRemaining-1]&/@reachable[grid,pos],1]*)
+
+
+(* ::Input:: *)
+(*With[{grid=Characters/@StringSplit[s,"\n"]},f[grid,FirstPosition[grid,"S"],64]//Length]*)