Day 3

Day 3: Rucksack Reorganization

Day 3: Rucksack Reorganization

Input

input = """
vJrwpWtwJgWrhcsFMMfFFhFp
jqHRNqRjqzjGDLGLrsFMfFZSrLrFZsSL
PmmdzqPrVvPwwTWBwg
wMqvLMZHhHMvwLHjbvcjnnSBnvTQFn
ttgJtRGJQctTZtZT
CrZsJsPPZsGzwwsLwLmpwMDw
"""

Part 1

f = fn line, range ->
  String.slice(line, range)
  |> String.to_charlist()
  |> MapSet.new()
end

scores = ?a..?z |> Enum.zip(1..26) |> Kernel.++(Enum.zip(?A..?Z, 27..52)) |> Map.new()

input
|> String.split("\n", trim: true)
|> Enum.map(fn line ->
  len = String.length(line)

  f.(line, 0..(div(len, 2) - 1))
  |> MapSet.intersection(f.(line, div(len, 2)..-1))
  |> Enum.at(0)
  |> then(&Map.fetch!(scores, &1))
end)
|> Enum.sum()

Part 2

f = fn line ->
  line
  |> String.to_charlist()
  |> MapSet.new()
end

scores = ?a..?z |> Enum.zip(1..26) |> Kernel.++(Enum.zip(?A..?Z, 27..52)) |> Map.new()

input
|> String.split("\n", trim: true)
|> Enum.chunk_every(3)
|> Enum.map(fn lines ->
  lines
  |> Enum.map(f)
  |> Enum.reduce(fn line_map_set, acc ->
    MapSet.intersection(line_map_set, acc)
  end)
  |> Enum.at(0)
  |> then(&Map.fetch!(scores, &1))
end)
|> Enum.sum()