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@@ -0,0 +1,100 @@
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+
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+module Collatz exposing (..)
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+
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+import Html exposing (..)
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+import Html.Events exposing (..)
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+import Html.Attributes exposing (id, class, style)
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+
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+import Hex
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+
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+type alias Model =
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+ {
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+ }
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+
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+initModel : Model
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+initModel =
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+ {
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+ }
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+
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+
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+type Msg
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+ = NoOp
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+
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+box : Int -> List Int -> Html Msg
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+box n p =
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+ let
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+ truval = List.length p
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+ val = round (atan (toFloat truval) * 2670177)
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+ code = "#" ++ (String.padLeft 6 '0' (Hex.toString val))
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+ fore =
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+ if truval < 127 then
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+ "#ffffff"
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+ else
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+ "#000000"
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+ in
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+ div
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+ [ class "box"
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+ , style
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+ [ ("background-color", code)
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+ , ("color", fore)
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+ ]
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+ ]
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+ [ text (toString n) ]
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+
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+collatzSteps : Int -> Int
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+collatzSteps n =
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+ let
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+ inner (n, c) =
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+ case n of
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+ 1 ->
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+ (n, c)
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+ _ ->
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+ if (rem n 2) == 0 then
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+ inner ((n // 2), (c + 1))
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+ else
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+ inner ((n * 3 + 1), (c + 1))
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+ (one, steps) = inner (n, 0)
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+ in
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+ steps
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+
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+collatzPath : Int -> List Int
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+collatzPath n =
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+ let
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+ helper n p =
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+ case n of
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+ 1 ->
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+ (n :: p)
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+ _ ->
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+ if (rem n 2) == 0 then
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+ helper (n // 2) (n :: p)
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+ else
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+ helper (n * 3 + 1) (n :: p)
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+ in
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+ helper n []
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+
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+view : Model -> Html Msg
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+view model =
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+ div
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+ []
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+ <|
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+ List.map (\n -> (box n (collatzPath n))) (List.range 1 777)
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+
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+update : Msg -> Model -> (Model, Cmd Msg)
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+update msg model =
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+ ( model, Cmd.none )
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+
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+--subscriptions : Model -> Sub Msg
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+--subscriptions model =
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+-- Sub.batch
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+-- [
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+-- ]
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+
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+main =
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+ Html.program
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+ { init = (initModel, Cmd.none)
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+ , view = view
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+ , update = update
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+ , subscriptions = \_ -> Sub.none
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+ }
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+
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+
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Brandon Wong
8 years ago