[Elixir] adventofcode 2018 Day 2

2018_d2.exs

### Part 1

data = ["kbqwtcvzgumhpwelrnaxydpfuj", "kbqwtcvzgsmhpoelryaxydiqij",
 "kbqwpcvzssmhpoelgnaxydifuj", "kbqgtcvxgsmhpoalrnaxydifuj",
 "kbqwtcvygsmhpoelrnaxydiaut", "kbqwtcvjgsmhpoelrnawydzfuj"]
 
 # count the duplicated char
process = fn x ->
  x
  |> Enum.chunk_every(1)
  |> Enum.group_by(& &1)
  |> Enum.filter(fn {_, y} -> Enum.count(y) != 1 end)
  |> Enum.map(fn {_, v} -> Enum.count(v) end)
  |> Enum.uniq()
end

data 
  |> Enum.map(&to_charlist/1) 
  |> Enum.map(process) 
  |> List.flatten() 
  |> Enum.group_by(& &1)
  
  
  # part 2
  
  defmodule WildTier do
  @wild '*'

  def add(root, key, value) do
    key
    |> Enum.map(fn _ -> to_string(key) end)
    |> Enum.with_index()
    |> Enum.map(fn {k, i} -> String.slice(k, 0, i) <> "*" <> String.slice(k, (i + 1)..-1) end)
    |> Enum.map(&to_charlist/1)
    |> Enum.reduce(root, &(insert(&2, &1, value)))
    |> insert(key, value)
  end

  defp insert(root, key, value) when length(key) == 1 do
    Map.update(root, key, [value], &[value | &1])
  end

  defp insert(root, key, value) when length(key) > 1 do
    [h | t] = key
    sub = Map.get(root, to_charlist(<<h>>), %{})
    Map.put(root, to_charlist(<<h>>), insert(sub, t, value))
  end

  def find?(root, _, _) when map_size(root)==0, do: nil

  def find?(root, key, wild) when length(key) == 1 and wild > 0 do
    Map.get(root, key, Map.get(root, @wild))
  end

  def find?(root, key, wild) when length(key) == 1 and wild == 0 do
    Map.get(root, key, nil)
  end

  def find?(root, key, wild) when length(key) > 1 and wild == 0 do
    [h | t] = key

    if Map.has_key?(root, to_charlist(<<h>>)) do
      root
      |> Map.get(to_charlist(<<h>>))
      |> find?(t, wild)
    else
      nil
    end
  end

  def find?(root, key, wild) when length(key) > 1 and wild > 0 do
    [h | t] = key

    if Map.has_key?(root, to_charlist(<<h>>)) do
      root
      |> Map.get(to_charlist(<<h>>))
      |> find?(t, wild)
    else
      wild = wild - 1
      root
      |> Map.get(@wild)
      |> find?(t, wild)
    end
  end
end

Enum.reduce_while(data, acc, fn x, acc ->
  value = WildTier.find?(acc, x, 1)
  if value != nil do
    {:halt, {value, x}}
  else
    {:cont, WildTier.add(acc, x, x)}
  end
end)