Solution to Advent of Code 2015 - Day 1 (https://adventofcode.com/2015/day/1)

Day01.elm

module Main exposing (main)

import Html exposing (Html, div, strong, text)


partOne : Html a
partOne =
    div []
        [ strong [] [ text "Part 1: " ]
        , puzzleInput |> parseInput |> findEndingFloor |> String.fromInt |> text
        ]


partTwo : Html a
partTwo =
    div []
        [ strong [] [ text "Part 2: " ]
        , puzzleInput |> parseInput |> findPositionOfBasement |> Maybe.map String.fromInt |> Maybe.withDefault "Basement position not found!" |> text
        ]


main : Html a
main =
    div []
        [ partOne
        , partTwo
        ]


type Direction
    = Up
    | Down


type alias FloorNumber =
    Int


type alias FloorNumberPosition =
    Int


type alias Directions =
    List Direction


findEndingFloor : Directions -> FloorNumber
findEndingFloor initialDirections =
    let
        initialFloor =
            0
    in
    List.foldl
        (\direction currentFloor -> nextFloor currentFloor direction)
        initialFloor
        initialDirections


findPositionOfBasement : Directions -> Maybe FloorNumberPosition
findPositionOfBasement initialDirections =
    let
        basementFloor =
            0

        initialFloor =
            0

        initialPosition =
            1

        findBasement directions position currentFloor =
            case directions of
                [] ->
                    Nothing

                direction :: remaining_directions ->
                    let
                        floor =
                            nextFloor currentFloor direction
                    in
                    if floor == basementFloor then
                        Just (position + 1)

                    else
                        findBasement remaining_directions (position + 1) floor
    in
    findBasement initialDirections initialPosition initialFloor


nextFloor : FloorNumber -> Direction -> FloorNumber
nextFloor currentFloor direction =
    case direction of
        Up ->
            currentFloor + 1

        Down ->
            currentFloor - 1


parseInput : String -> Directions
parseInput input =
    String.foldr
        (\char directions ->
            case char of
                '(' ->
                    Up :: directions

                ')' ->
                    Down :: directions

                _ ->
                    directions
        )
        []
        input


puzzleInput : String
puzzleInput =
    "((((()(()(((((((()))(((()((((()())(())()(((()((((((()((()(()(((()(()((())))()((()()())))))))))()((((((())((()))(((((()(((((((((()()))((()(())()((())((()(()))((()))()))()(((((()(((()()))()())((()((((())()())()((((())()(()(()(((()(())(()(())(((((((())()()(((())(()(()(()(())))(()((((())((()))(((()(()()(((((()()(()(((()(((((())()))()((()(()))()((()((((())((((())(()(((())()()(()()()()()(())((((())((())(()()))()((((())))((((()())()((((())((()())((())(())(((((()((((()(((()((((())(()(((()()))()))((((((()((())()())))(((()(()))(()()(()(((()(()))((()()()())((()()()(((())())()())())())((()))(()(()))(((((()(()(())((()(())(())()((((()())()))((((())(())((())())((((()(((())(())((()()((((()((((((()(())()()(()(()()((((()))(())()())()))(())))(())))())()()(())(()))()((()(()(())()()))(()())))))(()))(()()))(())(((((()(()(()()((())()())))))((())())((())(()(())((()))(())(((()((((((((()()()(()))()()(((()))()((()()(())(())())()(()(())))(((((()(())(())(()))))())()))(()))()(()(((((((()((((())))())())())())()((((((((((((((()()((((((()()()())())()())())())(())(())))())((()())((()(()))))))()))))))))))))))))())((())((())()()))))))(((()((()(()()))((())(()()))()()())))(())))))))(()(((())))())()())))()()(())()))()(()))())((()()))))(()))))()))(()()(())))))))()(((()))))()(()))(())())))))()))((()))((()))())(())))))))))((((())()))()))()))())(())()()(())))())))(()())()))((()()(())))(())((((((()(())((()(((()(()()(())))()))))))()))()(()((()))()(()))(()(((())((((())())(())(()))))))))())))))))())())))))())))))()()(((())()(()))))))))())))))(())()()()))()))()))(()(())()()())())))))))())()(()(()))))()()()))))())(()))))()()))))()())))))(((())()()))(()))))))))))()()))))()()()))))(()())())()()())()(()))))()(()))(())))))))(((((())(())())()()))()()))(())))))()(()))))(())(()()))()())()))()))()))()))))())()()))())())))(()))(()))))))())()(((())()))))))))()))()())))())))())))()))))))))))()()))(()()))))))(())()(()))))())(()))))(()))))(()())))))())())()()))))())()))))))))(()))))()))))))()(()())))))))()))())))())))())))())))))))())(()()))))))(()())())))()())()))))))))))))))())))()(())))()))())()()(())(()()))(())))())()())(()(()(()))))())))))))))))())(()))()))()))))(())()())()())))))))))))()()))))))))))))())())))))(()())))))))))))())(())))()))))))))())())(()))()))(())))()))()()(())()))))))()((((())()))())())))))()))()))))((()())()))))())))(())))))))))))))))))()))))()()())()))()()))))())()))((()())))())))(()))(()())))))))()))()))))(())))))))(())))))())()()(()))())()))()()))))())()()))))())()))())))))))(()))))()())()))))))))(()))())))(()))()))))(())()))())())(())())())))))))((((())))))()))()))()())()(())))()))()))()())(()())()()(()())()))))())())))))(()))()))))())(()()(())))))(())()()((())())))))(())(())))))))())))))))))()(())))))))()())())())()(()))))))))(()))))))))())()()))()(()))))))()))))))())))))))(())))()()(())()())))))(((())))()((())()))())))(()()))())(())())))()(((()())))))()(()()())))()()(()()(()()))())()(()()()))())()()))()())(()))))())))))())))(())()()))))(()))))(())(()))(())))))()()))()))))())()))()()(())())))((()))())()))))))()()))))((()(()))))()()))))))())))))())(()((()())))))))))))()())())))()))(()))))))(()))(())()())))(()))))))))())()()()()))))(()())))))))((())))()))(()))(())(())()())()))))))))(())))())))(()))()()))(()()))(()))())))()(())))())((()((()(())))((())))()))))((((())())()())))(())))()))))))())(()()((())))())()(()())))))(()())()))())))))))((())())))))))(()(()))())()()(()()(((()(((()())))))()))))))()(())(()()((()()(())()()))())()())()))()())())())))))))(((())))))))()()))))))(((())()))(()()))(()()))))(()(()()((((())()())((()()))))(()(())))))()((()()()())()()((()((()()))(()))(((()()()))(((())))()(((())()))))))((()(())())))(()())(((((()(()))(()((()))(()())()))))(()(()))()(()))(())(((())(()()))))()()))(((()))))(()()()()))())))((()()()(())()))()))))()()))()))))))((((((()()()))))())((()()(((()))))(()(())(()()())())())))()(((()()))(())((())))(()))(()()()())((())())())(()))))()))()((()(())()(()()(())(()))(())()))(())(()))))(())(())())(()()(()((()()((())))((()))()((())))(((()()()()((((()))(()()))()()()(((())((())())(()()(()()()))()((())(())()))())(((()()(())))()((()()())()())(()(())())(((())(())())((())(())()(((()()))(())))((())(()())())(())((()()()((((((())))((()(((((())()))()))(())(()()))()))(())()()))(())((()()())()()(()))())()((())))()((()()())((((()())((())())())((()((()))()))((())((()()(()((()()(((())(()()))))((()((())()(((())(()((())())((())(()((((((())())()(()())()(())(((())((((((()(())(()((()()()((()()(()()()())))()()(((((()()))()((((((()))()(()(()(()(((()())((()))())()((()))(())))()))()()))())()()))())((((())(()(()))(((((((())(((()(((((()(((()()((((())(((())())))(()()()(()(()))()))((((((()))((()(((()(())((()((((()((((((())(((((())))(((()(()))))(((()(((())()((())(()((()))(((()()(((())((((()(()(((((()))(((()(((((((()(()()()(()(()(()()())(())(((((()(())())()())(()(()(()))()(()()()())(()()(()((()))()((())())()(()))((())(()))()(()))()(((()(()(()((((((()()()()())()(((((()()(((()()()((()(((((()))((((((((()()()(((((()))))))(()()()(())(()))(()()))))((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