Advent of Code (AOC) 2017 Day 4

day4.ex

  defmodule Day4 do
    def parser( input ) do
      String.split( input, "\n" )
      |> Enum.reduce( [], fn "", acc -> acc; line,acc -> [ String.split(line," ") | acc ] end )
    end

    def start1( input ) do
      parser( input ) |> step1a( [valid: 0, invalid: 0] )
    end

    def step1a( [ line | rest ], [ valid: v, invalid: i ] ) do
      Enum.sort( line )
      |> step1b
      |> case do
           true -> step1a( rest, [ valid: v+1, invalid: i ] )
           false -> step1a( rest, [ valid: v, invalid: i+1 ] )
         end
    end
    def step1a( [ ], result ), do: result

    def step1b( [ w1, w1 | rest ] ), do: false
    def step1b( [ _ | rest ] ), do: step1b( rest )
    def step1b( [] ), do: true

    def	start2( input )	do
      parser( input ) |> step2a( [ valid: 0, invalid: 0 ] )
    end

    def	step2a( [ line | rest ], [ valid: v, invalid: i ] ) do
      line
      |> Enum.map( fn word -> String.to_charlist(word) |> Enum.sort end )
      |> Enum.sort
      |> step1b
      |> case do
           true	-> step2a( rest, [ valid: v+1, invalid: i ] )
           false -> step2a( rest, [ valid: v, invalid: i+1 ] )
         end
    end
    def	step2a( [], result ), do: result
  end