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Advent of Code (2016) : Day 6

-- Problem --
You can find Part 1 of the problem statement here. Part 2 is unlocked on successful completion of Part 1.

-- Solution in Elixir --

      defmodule Aoc.Day6 do

  def parse_input() do
    {:ok, input} = File.read("day6_input.txt")
    String.split(input)
    |> Stream.map(&String.graphemes/1)
    |> Enum.reduce(List.duplicate([],8), fn([e1,e2,e3,e4,e5,e6,e7,e8],[l1,l2,l3,l4,l5,l6,l7,l8]) ->
      [[e1|l1],[e2|l2],[e3|l3],[e4|l4],[e5|l5],[e6|l6],[e7|l7],[e8|l8]]
    end)
  end

  def most_common_character(list_with_dups) do
    Stream.uniq(list_with_dups)
    |> Stream.map(&({count_occurrences(list_with_dups, &1), &1}))
    |> Enum.max |> elem(1)
  end

  def least_common_character(list_with_dups) do
    Stream.uniq(list_with_dups)
    |> Stream.map(&({count_occurrences(list_with_dups, &1), &1}))
    |> Enum.min |> elem(1)
  end

  def count_occurrences(list, target_elem) do
    Enum.reduce(list, 0, fn(elem, count) ->
      case elem == target_elem do
        true -> count + 1
        false -> count
      end
    end)
  end

  def output_1() do
    parse_input()
    |> Enum.map_join(&most_common_character/1)
  end

  def output_2() do
    parse_input()
    |> Enum.map_join(&least_common_character/1)
  end

end

    

You can find all my Advent of Code (2016) solutions here.