Part 1

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

@@ -24,6 +24,7 @@
     <Compile Include="Day11.fs" />
     <Compile Include="Day12.fs" />
     <Compile Include="Day13.fs" />
+    <Compile Include="Day14.fs" />
   </ItemGroup>
 
 </Project>

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

@@ -0,0 +1,97 @@
+namespace AdventOfCode2023
+
+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 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 print (board : Arr2D<byte>) =
+        for row = 0 to board.Height - 1 do
+            for col = 0 to board.Width - 1 do
+                match Arr2D.get board col row with
+                | 0uy -> printf "."
+                | 1uy -> printf "O"
+                | 2uy -> printf "#"
+                | _ -> failwith "bad value"
+            printfn ""
+        printfn ""
+
+    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 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 part2 (s : string) =
+        use mutable lines = StringSplitEnumerator.make '\n' s
+        let mutable answer = 0
+
+        for line in lines do
+            ()
+
+        answer