stockprice.fsx

open System.IO

let prices = File.ReadLines(__SOURCE_DIRECTORY__ + "/2/input.txt")
              |> Seq.map System.Double.Parse
              |> Seq.toList

let rec findMax price prices profit =
  match prices with
  | [] -> profit
  | hd :: tail ->
    if hd - price > profit then findMax price tail (hd - price)
    else findMax price tail profit

let rec solve prices profit =
  match prices with
  | [] -> profit
  | hd :: tail ->
      let candidate = findMax hd tail profit
      if candidate > profit then solve tail candidate
      else solve tail profit

printfn "Max profit: %.4f" (solve prices 0.0)