From 3efe77de076673d2e0c2a20a0a64a69dd384fd68 Mon Sep 17 00:00:00 2001
From: Malachy Byrne <malachybyrne1@gmail.com>
Date: Sun, 7 Dec 2025 20:39:55 +0000
Subject: [PATCH] Add day 7

---
 advent-of-code/Program.fs           | 52 ++++++++++++++++-------------
 advent-of-code/tasks/day-7/Star1.fs | 30 +++++++++++++++++
 advent-of-code/tasks/day-7/Star2.fs | 37 ++++++++++++++++++++
 3 files changed, 95 insertions(+), 24 deletions(-)
 create mode 100644 advent-of-code/tasks/day-7/Star1.fs
 create mode 100644 advent-of-code/tasks/day-7/Star2.fs

diff --git a/advent-of-code/Program.fs b/advent-of-code/Program.fs
index e7ab7f8..7afa75e 100644
--- a/advent-of-code/Program.fs
+++ b/advent-of-code/Program.fs
@@ -4,28 +4,32 @@ open advent_of_code.tasks
 
 [<EntryPoint>]
 let main _ =
-    let _, day1Star1 = day_1.Star1.main 50 0
-    printfn $"{day1Star1}"
-    let _, day1Star2 = day_1.Star2.main 50 0
-    printfn $"{day1Star2}"
-    let day2Star1 = day_2.Star1.main
-    printfn $"{day2Star1}"
-    let day2Star2 = day_2.Star2.main
-    printfn $"{day2Star2}"
-    let day3Star1 = day_3.Star1.main
-    printfn $"{day3Star1}"
-    let day3Star2 = day_3.Star2.main
-    printfn $"{day3Star2}"
-    let day4Star1 = day_4.Star1.main
-    printfn $"{day4Star1}"
-    let day4Star2 = day_4.Star2.main
-    printfn $"{day4Star2}"
-    let day5Star1 = day_5.Star1.main
-    printfn $"%A{day5Star1}"
-    let day5Star2 = day_5.Star2.main
-    printfn $"%A{day5Star2}"
-    let day6Star1 = day_6.Star1.main
-    printfn $"%A{day6Star1}"
-    let day6Star2 = day_6.Star2.main
-    printfn $"%A{day6Star2}"
+    // let _, day1Star1 = day_1.Star1.main 50 0
+    // printfn $"{day1Star1}"
+    // let _, day1Star2 = day_1.Star2.main 50 0
+    // printfn $"{day1Star2}"
+    // let day2Star1 = day_2.Star1.main
+    // printfn $"{day2Star1}"
+    // let day2Star2 = day_2.Star2.main
+    // printfn $"{day2Star2}"
+    // let day3Star1 = day_3.Star1.main
+    // printfn $"{day3Star1}"
+    // let day3Star2 = day_3.Star2.main
+    // printfn $"{day3Star2}"
+    // let day4Star1 = day_4.Star1.main
+    // printfn $"{day4Star1}"
+    // let day4Star2 = day_4.Star2.main
+    // printfn $"{day4Star2}"
+    // let day5Star1 = day_5.Star1.main
+    // printfn $"%A{day5Star1}"
+    // let day5Star2 = day_5.Star2.main
+    // printfn $"%A{day5Star2}"
+    // let day6Star1 = day_6.Star1.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
diff --git a/advent-of-code/tasks/day-7/Star1.fs b/advent-of-code/tasks/day-7/Star1.fs
new file mode 100644
index 0000000..aafa40d
--- /dev/null
+++ b/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)
diff --git a/advent-of-code/tasks/day-7/Star2.fs b/advent-of-code/tasks/day-7/Star2.fs
new file mode 100644
index 0000000..2857313
--- /dev/null
+++ b/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)
\ No newline at end of file