2 files changed, 50 insertions, 0 deletions
diff --git a/aoc-2022-dotnet/Day04/Day04.fsproj b/aoc-2022-dotnet/Day04/Day04.fsproj
new file mode 100644
index 0000000..44c3fba
--- /dev/null
+++ b/aoc-2022-dotnet/Day04/Day04.fsproj
@@ -0,0 +1,22 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net7.0</TargetFramework>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Content Include="test.txt">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </Content>
+    <Content Include="input.txt">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </Content>
+    <Compile Include="Program.fs" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="FParsec" Version="1.1.1" />
+  </ItemGroup>
+
+</Project>
diff --git a/aoc-2022-dotnet/Day04/Program.fs b/aoc-2022-dotnet/Day04/Program.fs
new file mode 100644
index 0000000..25cc3b6
--- /dev/null
+++ b/aoc-2022-dotnet/Day04/Program.fs
@@ -0,0 +1,28 @@
+module Day04
+
+open System.IO
+open FParsec
+
+let parseLine line =
+    let prange = pint32 .>> pstring "-" .>>. pint32
+    let ppair = prange .>> pstring "," .>>. prange .>> eof
+
+    match run ppair line with
+    | Success (result, _, _) -> result
+    | _ -> failwith "Invalid line format!"
+
+let fullyOverlap ((a, b), (c, d)) =
+    (a <= c && d <= b) || (c <= a && b <= d)
+
+let overlapAtAll ((a, b), (c, d)) = a <= d && b >= c
+
+let solution pred =
+    Seq.map parseLine >> Seq.filter pred >> Seq.length
+
+let test = File.ReadLines "test.txt"
+assert (solution fullyOverlap test = 2)
+assert (solution overlapAtAll test = 4)
+
+let input = File.ReadAllLines "input.txt"
+printfn "%d" <| solution fullyOverlap input
+printfn "%d" <| solution overlapAtAll input