Files
advent-of-code-2023/AdventOfCode2023.FSharp/AdventOfCode2023.FSharp.Lib/Day12.fs
Smaug123 511814f241 Part 1
2023-12-12 08:55:29 +00:00

60 lines
2.2 KiB
Forth

namespace AdventOfCode2023
open System
open System.Collections.Generic
open System.Globalization
[<RequireQualifiedAccess>]
module Day12 =
let rec solve (line : ReadOnlySpan<char>) (groups : IReadOnlyList<int>) (currentGroupIndex : int) =
match line.[0] with
| '#' ->
if currentGroupIndex >= groups.Count then 0 else
let mutable isOk = true
for i = 1 to groups.[currentGroupIndex] - 1 do
if isOk && line.[i] <> '#' && line.[i] <> '?' then
isOk <- false
if not isOk then 0 else
if line.[groups.[currentGroupIndex]] = '#' then 0 else
solve (line.Slice (groups.[currentGroupIndex] + 1)) groups (currentGroupIndex + 1)
| '.' ->
solve (line.Slice 1) groups currentGroupIndex
| '?' ->
let ifDot = solve (line.Slice 1) groups currentGroupIndex
let ifHash =
if currentGroupIndex >= groups.Count then 0 else
let mutable isOk = true
for i = 1 to groups.[currentGroupIndex] - 1 do
if isOk && line.[i] <> '#' && line.[i] <> '?' then
isOk <- false
if not isOk then 0 else
if line.[groups.[currentGroupIndex]] = '#' then 0 else
solve (line.Slice (groups.[currentGroupIndex] + 1)) groups (currentGroupIndex + 1)
ifDot + ifHash
| _ ->
if currentGroupIndex = groups.Count then 1 else 0
let part1 (s : string) =
use mutable lines = StringSplitEnumerator.make '\n' s
let mutable answer = 0
let arr = ResizeArray ()
for line in lines do
if not line.IsEmpty then
arr.Clear ()
use ints = StringSplitEnumerator.make' ',' (line.Slice (line.IndexOf ' ' + 1))
for int in ints do
arr.Add (Int32.Parse (int, NumberStyles.None, CultureInfo.InvariantCulture))
let solved = solve line arr 0
answer <- answer + solved
answer
let part2 (s : string) =
use mutable lines = StringSplitEnumerator.make '\n' s
-1