Project Euler 18

euler18.fs

#light

type System.String with
    member s.split (sep : char) = s.Split([|sep|]) |> Array.toList

let parseNumbersPyramid (s : string) =
    [for x in (s.split '\n') -> x.Trim().split ' ' |> List.map int]

let greaters xs =
    Seq.map2 max xs (List.tail xs)
    |> Seq.toList

let euler18 =
    parseNumbersPyramid 
    >> List.reduceBack (fun xs ys -> List.map2 (+) (greaters ys) xs)
    >> List.head

[<EntryPoint>]
let main _ =
    @"        75
             95 64
            17 47 82
           18 35 87 10
          20 04 82 47 65
         19 01 23 75 03 34
        88 02 77 73 07 63 67
       99 65 04 28 06 16 70 92
      41 41 26 56 83 40 80 70 33
     41 48 72 33 47 32 37 16 94 29
    53 71 44 65 25 43 91 52 97 51 14
   70 11 33 28 77 73 17 78 39 68 17 57
  91 71 52 38 17 14 91 43 58 50 27 29 48
 63 66 04 68 89 53 67 30 73 16 69 87 40 31
04 62 98 27 23 09 70 98 73 93 38 53 60 04 23" |> euler18 |> printfn "%d"

    0 // return value from main