Add day one solutions

advent-of-code/Program.fs

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+module advent_of_code.Program
+
+open advent_of_code.tasks.day_1
+
+[<EntryPoint>]
+let main _ =
+    let _, day1Star1 = Star1.main 50 0
+    printfn $"{day1Star1}"
+    let _, day1Star2 = Star2.main 50 0
+    printfn $"{day1Star2}"
+    0

advent-of-code/tasks/day-1/Star1.fs

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+module advent_of_code.tasks.day_1.Star1
+
+open System.IO
+
+let stream = new StreamReader("tasks/day-1/input.txt")
+
+let diff (line: string) =
+    let direction = if line.StartsWith("R") then 1 else -1
+    let count = (line.[1..] |> int)
+    direction * count
+    
+let solve (line: string) (start: int) =
+    let change = diff line
+    let newPos = (start + change) % 100
+    (newPos, if newPos = 0 then 1 else 0)
+
+let rec main start zeroes =
+    let line = stream.ReadLine()
+    let newPos, newZeroes = solve line start
+    if stream.EndOfStream then
+        (newPos, zeroes + newZeroes)
+    else
+        main newPos (zeroes + newZeroes)

advent-of-code/tasks/day-1/Star2.fs

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+module advent_of_code.tasks.day_1.Star2
+
+open System.IO
+
+let stream = new StreamReader("tasks/day-1/input.txt")
+
+let diff (line: string) =
+    let direction = if line.StartsWith("R") then 1 else -1
+    let count = (line.[1..] |> int)
+    // if (direction = -1) then
+        // printfn $"Turning left: {line} produces {count}"
+    direction * count
+    
+let solve (line: string) (start: int) =
+    let change = diff line
+    let changeMod100 = change % 100
+    let newPos = start + changeMod100
+    // printfn $"Line {line} produces change of {change} turns {changeMod100} moving from {start} to {newPos}"
+    let zeroesFound = (abs change / 100) + (if start <> 0 && (newPos <= 0 || newPos >= 100) then 1 else 0)
+    (newPos % 100 + (if newPos < 0 then 100 else 0), zeroesFound)
+
+let rec main start zeroes =
+    let line = stream.ReadLine()
+    let newPos, newZeroes = solve line start
+    if stream.EndOfStream then
+        (newPos, zeroes + newZeroes)
+    else
+        main newPos (zeroes + newZeroes)