Day 2

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

@@ -9,6 +9,7 @@
         <Compile Include="Arr2D.fs" />
         <Compile Include="EfficientString.fs" />
         <Compile Include="Day1.fs" />
+        <Compile Include="Day2.fs" />
         <Compile Include="Day3.fs" />
     </ItemGroup>
 

AdventOfCode2023.FSharp/AdventOfCode2023.FSharp.Lib/Day2.fs

@@ -0,0 +1,61 @@
+namespace AdventOfCode2023
+
+open System
+
+[<RequireQualifiedAccess>]
+module Day2 =
+
+    let part1 (s : string) =
+        use lines = StringSplitEnumerator.make '\n' s
+        let mutable answer = 0
+
+        for line in lines do
+            if not line.IsEmpty then
+                use mutable words = StringSplitEnumerator.make' ' ' line
+                let mutable prevWord = ReadOnlySpan<char>.Empty
+                let mutable isOk = true
+
+                while isOk && words.MoveNext () do
+                    match words.Current.[0] with
+                    | 'b' ->
+                        if Int32.Parse prevWord > 14 then
+                            isOk <- false
+                    | 'r' ->
+                        if Int32.Parse prevWord > 12 then
+                            isOk <- false
+                    | 'g' ->
+                        if Int32.Parse prevWord > 13 then
+                            isOk <- false
+                    | _ -> ()
+
+                    prevWord <- words.Current
+
+                if isOk then
+                    answer <- answer + Int32.Parse (line.Slice (5, line.IndexOf ':' - 5))
+
+        answer
+
+    let part2 (s : string) =
+        use lines = StringSplitEnumerator.make '\n' s
+        let mutable answer = 0
+
+        for line in lines do
+            if not line.IsEmpty then
+                let mutable reds = 0
+                let mutable blues = 0
+                let mutable greens = 0
+                use mutable words = StringSplitEnumerator.make' ' ' line
+                let mutable prevWord = ReadOnlySpan<char>.Empty
+
+                while words.MoveNext () do
+                    match words.Current.[0] with
+                    | 'b' -> blues <- max blues (Int32.Parse prevWord)
+                    | 'r' -> reds <- max reds (Int32.Parse prevWord)
+                    | 'g' -> greens <- max greens (Int32.Parse prevWord)
+                    | _ -> ()
+
+                    prevWord <- words.Current
+
+                answer <- answer + (reds * greens * blues)
+
+        answer

AdventOfCode2023.FSharp/Test/Test.fsproj

@@ -9,6 +9,7 @@
 
     <ItemGroup>
         <Compile Include="TestDay1.fs" />
+        <Compile Include="TestDay2.fs" />
         <Compile Include="TestDay3.fs" />
     </ItemGroup>
 

AdventOfCode2023.FSharp/Test/TestDay2.fs

@@ -0,0 +1,46 @@
+namespace AdventOfCode2023.Test
+
+open AdventOfCode2023
+open NUnit.Framework
+open FsUnitTyped
+open System.IO
+
+[<TestFixture>]
+module TestDay2 =
+
+    let sample =
+        """Game 1: 3 blue, 4 red; 1 red, 2 green, 6 blue; 2 green
+Game 2: 1 blue, 2 green; 3 green, 4 blue, 1 red; 1 green, 1 blue
+Game 3: 8 green, 6 blue, 20 red; 5 blue, 4 red, 13 green; 5 green, 1 red
+Game 4: 1 green, 3 red, 6 blue; 3 green, 6 red; 3 green, 15 blue, 14 red
+Game 5: 6 red, 1 blue, 3 green; 2 blue, 1 red, 2 green
+"""
+
+    [<Test>]
+    let part1Sample () = sample |> Day2.part1 |> shouldEqual 8
+
+    [<Test>]
+    let part2Sample () =
+        sample |> Day2.part2 |> shouldEqual 2286
+
+    [<Test>]
+    let part1Actual () =
+        let s =
+            try
+                File.ReadAllText (Path.Combine (__SOURCE_DIRECTORY__, "../../inputs/day2.txt"))
+            with :? FileNotFoundException ->
+                Assert.Inconclusive ()
+                failwith "unreachable"
+
+        Day2.part1 s |> shouldEqual 2727
+
+    [<Test>]
+    let part2Actual () =
+        let s =
+            try
+                File.ReadAllText (Path.Combine (__SOURCE_DIRECTORY__, "../../inputs/day2.txt"))
+            with :? FileNotFoundException ->
+                Assert.Inconclusive ()
+                failwith "unreachable"
+
+        Day2.part2 s |> shouldEqual 56580