Initial commit, day 1

AdventOfCode2022/AdventOfCode2022.fsproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <TargetFramework>net6.0</TargetFramework>
+        <GenerateDocumentationFile>true</GenerateDocumentationFile>
+    </PropertyGroup>
+
+    <ItemGroup>
+        <Compile Include="Day1.fs" />
+    </ItemGroup>
+
+</Project>

AdventOfCode2022/Day1.fs

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+namespace AdventOfCode2022
+
+open System
+
+[<RequireQualifiedAccess>]
+module Day1 =
+
+    let counts (lines : string seq) : int list =
+        ((0, []), lines)
+        ||> Seq.fold (fun (acc, counts) line ->
+            if String.IsNullOrWhiteSpace line then
+                0, (acc :: counts)
+            else
+                match Int32.TryParse line with
+                | false, _ -> failwithf "not an int: %s" line
+                | true, v -> acc + v, counts
+        )
+        |> snd
+
+    /// Expects a trailing newline (as is present in the given input data).
+    let part1 (lines : string seq) : int = lines |> counts |> List.max
+
+    /// I wanted to save cloning the entire seq, so here is some bonus efficiency.
+    let maxThree (inputs : int list) : struct (int * int * int) =
+        ((struct (Int32.MinValue, Int32.MinValue, Int32.MinValue)), inputs)
+        ||> List.fold (fun (struct (max1, max2, max3) as maxes) input ->
+            if input <= max3 then maxes
+            elif input <= max2 then struct (max1, max2, input)
+            elif input <= max1 then struct (max1, input, max2)
+            else struct (input, max1, max2)
+        )
+
+    let part2 (lines : string seq) : int =
+        let struct (a, b, c) = lines |> counts |> maxThree
+
+        a + b + c