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| -rw-r--r-- | day9.fsx | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/day9.fsx b/day9.fsx new file mode 100644 index 0000000..de64fea --- /dev/null +++ b/day9.fsx @@ -0,0 +1,36 @@ +open System.IO +open System.Text.RegularExpressions + +let (|Regex|_|) input = + let m = Regex.Match(input, "^(?:\((\w+?)\))(.*)") + if m.Success then Some(List.tail [for g in m.Groups -> g.Value]) + else None + +let splitPattern str = + match str with + | Regex [marker; rest] -> marker, rest + | _ -> "", "" + +let rec decrypt str = + if str = "" then "" + else + let marker, rest = splitPattern str + if marker = "" then string str[0] + decrypt str[1..] + else + let nums = marker.Split 'x' |> Array.map int + let start, count = (min nums[0] (String.length rest)), nums[1] + String.replicate count rest[..start-1] + decrypt rest[start..] + +let rec decryptLength str = + if str = "" then bigint 0 + else + let marker, rest = splitPattern str + if marker = "" then bigint 1 + decryptLength str[1..] + else + let nums = marker.Split 'x' |> Array.map int + let start, count = (min nums[0] (String.length rest)), nums[1] + bigint count * decryptLength rest[..start-1] + decryptLength rest[start..] + +let lines = File.ReadLines "day9.txt" +lines |> Seq.map decrypt |> Seq.map String.length |> Seq.reduce (+) |> printfn "%d" +lines |> Seq.map decryptLength |> Seq.reduce (+) |> printfn "%A" |