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module Main exposing (..)
import Array exposing (map)
import Browser
import Html exposing (Html, button, div, text)
import Html.Events exposing (onClick)
import Regex
import String
main =
Browser.sandbox { init = initModel, update = update, view = view }
type alias Model =
{ number : Int
, factorialOfNumber : Int
, trailingZeroes : Int
}
initModel =
{ number = 10
, factorialOfNumber = 0
, trailingZeroes = 0
}
type Msg
= Increment
| Decrement
update msg model =
case msg of
Increment ->
{ model | number = model.number + 1 }
Decrement ->
{ model | number = model.number - 1 }
view model =
div []
[ button [ onClick Decrement ] [ text "-" ]
, div [] [ text ("Number:" ++ String.fromInt model.number) ]
, div [] [ text ("Trailing zeroes of factorial:" ++ String.fromInt (calcFactorial model.number)) ]
, div [] [ text ("Factorial of number:" ++ String.fromInt (trailingZeroes (calcFactorial model.number))) ]
, button [ onClick Increment ] [ text "+" ]
]
calcFactorial : Int -> Int
calcFactorial n =
List.product (List.range 1 n)
trailingZeroes : Int -> Int
trailingZeroes x =
let
a =
List.head <|
Regex.find zeroes <|
String.fromInt x
in
case a of
Just foo ->
String.length foo.match
Nothing ->
0
zeroes =
Maybe.withDefault Regex.never (Regex.fromString "0+$")
|
