Day 9 Part 1

Kodfodrasz.AoC.Year2024.Tests/Day9Tests.fs

@@ -0,0 +1,84 @@
+module Kodfodrasz.AoC.Year2024.Tests.Day9Tests
+
+open Xunit
+open Swensen.Unquote.Assertions
+
+open Kodfodrasz.AoC
+open Kodfodrasz.AoC.Year2024
+open Kodfodrasz.AoC.Year2024.Day9
+
+
+let exampleInput = """
+2333133121414131402
+  """
+
+[<Fact>]
+let ``Parsing example input`` () =
+  let expected = [|
+    File (0, 2, 0)
+    Free (2, 3)
+    File (5, 3, 1)
+    Free (8, 3)
+    File (11, 1, 2)
+    Free (12, 3)
+    File (15, 3, 3)
+    Free (18, 1)
+    File (19, 2, 4)
+    Free (21, 1)
+    File (22, 4, 5)
+    Free (26, 1)
+    File (27, 4, 6)
+    Free (31, 1)
+    File (32, 3, 7)
+    Free (35, 1)
+    File (36, 4, 8)
+    Free (40, 0)
+    File (40, 2, 9)
+  |]
+
+  test
+    <@ let actual = parseInput exampleInput
+       actual = Ok expected @>
+
+
+[<Fact>]
+let ``Parsing example input for 12345`` () =
+  test
+    <@ 
+      let expected = Ok [|
+        File (0, 1, 0)
+        Free (1, 2)
+        File (3, 3, 1)
+        Free (6, 4)
+        File (10, 5, 2)
+      |] 
+      let actual = parseInput "12345"
+      actual = expected
+  @>
+
+[<Fact>]
+let ``Answer 1 for example input for 12345`` () =
+  let blocks = parseInput "12345" |> Result.get
+  // BLOCKS BEFORE: 0..111....22222
+  // BLOCKS AFTER : 022111222
+  // POS          : 0123456789
+  // CHECKSUM     : 60 = 0 + 2 + 4 + 3 + 4 + 5 + 12 + 14 + 16
+  test <@  answer1 blocks = Ok 60L @>
+
+[<Fact>]
+let ``Answer 1 for example input`` () =
+  let input = parseInput exampleInput
+
+  test
+    <@ let actual = Result.bind answer1 input
+       let expected: Result<_, string> = Ok 1928L
+       actual = expected @>
+
+[<Fact(Skip="TODO")>]
+let ``Answer 2 for example input`` () =
+  let input = parseInput exampleInput
+
+  test
+    <@ let actual = Result.bind answer2 input
+       let expected: Result<_, string> = Ok 31L
+       actual = expected @>

Kodfodrasz.AoC.Year2024.Tests/Kodfodrasz.AoC.Year2024.Tests.fsproj

@@ -14,6 +14,7 @@
     <Compile Include="Day6Tests.fs" />
     <Compile Include="Day7Tests.fs" />
     <Compile Include="Day8Tests.fs" />
+    <Compile Include="Day9Tests.fs" />
     <Compile Include="Day10Tests.fs" />
     <Compile Include="Day11Tests.fs" />
     <Compile Include="Day13Tests.fs" />

Kodfodrasz.AoC.Year2024/Day9.fs

@@ -0,0 +1,133 @@
+module Kodfodrasz.AoC.Year2024.Day9
+
+open System
+open System.Text.RegularExpressions
+open Kodfodrasz.AoC
+open System.Collections.Generic
+
+type Block = 
+  | File of pos : int * size : int * id : int 
+  | Free of pos : int * size : int
+
+let pos = function
+| File(pos, _, _) -> pos
+| Free(pos, _) -> pos
+
+let size = function
+| File(_, size, _) -> size
+| Free(_, size) -> size
+
+let fid = function
+| File(_, _, _id) -> _id
+| Free(_, _) -> failwith "Not a file"
+
+type BlockPosComparer() =
+    interface IComparer<Block> with
+        member _.Compare(x, y) =
+            compare (pos x) (pos y)
+
+type parsedInput = Block array
+let parseInput (input: string): Result<parsedInput,string> = 
+  let numbers = 
+    input.Split('\n', StringSplitOptions.TrimEntries ||| StringSplitOptions.RemoveEmptyEntries)
+    |> Seq.collect(String.toCharArray)
+    |> Seq.map (string >> int)
+    |> Seq.toArray
+
+  let blocks = 
+    numbers
+    |> Array.fold (fun (id, pos, l) n -> 
+        match l with
+        | [] | Free _ :: _ -> 
+          let f = File(pos, n, id)
+          (id + 1, pos + n, f :: l)
+        | File _ :: _->
+          let f = Free(pos, n)
+          (id, pos + n, f :: l)
+        ) (0, 0, List.empty)
+    |> (fun (_, _, l) -> List.rev l)
+
+  blocks
+  |> List.toArray
+  |> Ok
+
+let checksum blocks = 
+  Seq.sumBy(function
+      | File(pos, size, id) -> 
+          let mutable sum = 0L
+          for x in 0 .. size - 1 do
+            sum <- sum + int64(pos + x) * int64(id)
+          sum 
+      | Free _ -> 0
+  ) blocks
+
+let defrag1 blocks : Block array = 
+  let blocks = System.Collections.Generic.List<Block>(blocks :> Block seq)
+
+  let cmp = BlockPosComparer()
+  let mutable fragmented = true
+  while fragmented do
+    let firstFreeIdx = blocks.FindIndex(function
+      | Free (pos, size) -> size > 0
+      | _ -> false)
+    let lastFileIdx = blocks.FindLastIndex(function
+      | File(pos, size, id) -> true
+      | _ -> false)
+
+    fragmented <- firstFreeIdx >= 0 && lastFileIdx >= 0
+
+    if fragmented then
+      let free = blocks[firstFreeIdx]
+      let file = blocks[lastFileIdx]
+
+      if pos free > pos file then
+        blocks.RemoveAt(firstFreeIdx)
+      elif size free = size file then
+        blocks[firstFreeIdx] <- File(
+          pos free,
+          size file,
+          fid file)
+        blocks.RemoveAt(lastFileIdx)
+      elif size free > size file then
+        blocks[lastFileIdx] <- File(
+          pos free,
+          size file,
+          fid file)
+        blocks[firstFreeIdx] <- Free(
+          pos free + size file,
+          size free - size file)
+      else // file is bigger
+        blocks[firstFreeIdx] <- File(
+          pos free,
+          size free,
+          fid file)
+        blocks[lastFileIdx] <- File(
+          pos file,
+          size file - size free,
+          fid file)
+      blocks.Sort(cmp)
+
+  blocks.ToArray()
+
+let answer1 (blocks : parsedInput) =
+  blocks
+  |> defrag1
+  |> checksum
+  |> Ok
+
+let answer2 (data : parsedInput) =
+  failwith "TODO"
+
+type Solver() =
+  inherit SolverBase("Disk Fragmenter")
+  with
+    override this.Solve input =
+      input
+      |>
+      this.DoSolve
+        (parseInput)
+        [ 
+          answer1;
+          answer2;
+        ]
+

Kodfodrasz.AoC.Year2024/Kodfodrasz.AoC.Year2024.fsproj

@@ -14,6 +14,7 @@
     <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="Day13.fs" />