Add day 7

advent-of-code/Program.fs

@@ -28,4 +28,8 @@ let main _ =
     printfn $"%A{day6Star1}"
     let day6Star2 = day_6.Star2.main
     printfn $"%A{day6Star2}"
+    let day7Star1 = day_7.Star1.main
+    printfn $"%A{day7Star1}"
+    let day7Star2 = day_7.Star2.main
+    printfn $"%A{day7Star2}"
     0

advent-of-code/tasks/day-7/Star1.fs

@@ -0,0 +1,30 @@
+module advent_of_code.tasks.day_7.Star1
+
+open System.IO
+
+let stream = new StreamReader("tasks/day-7/input.txt")
+
+let containsSplit (s: string) =
+    s.Contains("^")
+
+let split (row: string) (pos: int) =
+    if row[pos] = '^' then
+        [|pos-1; pos+1|] |> Set.ofArray, 1
+    else
+        [|pos|] |> Set.ofArray, 0
+
+let rec getBeams (manifold: string array) (pos: Set<int>) =
+    if manifold.Length = 0 then
+        0
+    else
+        let row, tail = manifold[0], manifold[1..]
+        let mapRes = (pos |> Seq.map (split row))
+        let newPos = (mapRes |> Seq.map fst) |> Set.ofSeq |> Set.unionMany
+        let splits = mapRes |> Seq.map snd |> Seq.sum
+        getBeams tail newPos + splits
+
+let main =
+    let allLines = stream.ReadToEnd().Split("\n")
+    let startLine, manifold = allLines[0], (allLines[1..] |> Array.filter containsSplit)
+    let startPos = startLine.IndexOf("S")
+    getBeams manifold ([|startPos|] |> Set.ofArray)

advent-of-code/tasks/day-7/Star2.fs

@@ -0,0 +1,37 @@
+module advent_of_code.tasks.day_7.Star2
+
+open System
+open System.IO
+
+let stream = new StreamReader("tasks/day-7/input.txt")
+
+let containsSplit (s: string) =
+    s.Contains("^")
+
+let split (oldTimelines: int64 array) (newTimelines: int64 array) (t: int * char) =
+    let index, item = t.Deconstruct()
+    let mutable timelines = newTimelines
+    if item = '^' then
+        timelines[index-1] <- oldTimelines[index] + newTimelines[index-1]
+        timelines[index+1] <- oldTimelines[index] + newTimelines[index+1]
+    else
+        timelines[index] <- oldTimelines[index] + newTimelines[index]
+    timelines
+
+let rec getTimelines (manifold: string array) (prevTimelines: int64 array) =
+    if manifold.Length = 0 then
+        prevTimelines
+    else
+        let row, tail = manifold[0], manifold[1..]
+        let emptyTimeline = [1 .. row.Length] |> Seq.map (fun _ -> 0 |> int64) |> Array.ofSeq
+        let newTimeline = row |> seq |> Seq.mapi (fun index item -> index, item) |> Seq.fold (split prevTimelines) emptyTimeline
+        getTimelines tail newTimeline
+    
+
+let main =
+    let allLines = stream.ReadToEnd().Split("\n")
+    let startLine, manifold = allLines[0], (allLines[1..] |> Array.filter containsSplit)
+    let startPos = startLine.IndexOf("S")
+    let initialTimeline = [1..startLine.Length] |> Seq.map (fun _ -> 0 |> int64) |> Array.ofSeq
+    initialTimeline[startPos] <- 1
+    Array.sum (getTimelines manifold initialTimeline)