41 lines
1,005 B
Elixir
41 lines
1,005 B
Elixir
defmodule Day5 do
|
|
def upcase?(char), do: char in ?A..?Z
|
|
def same_letter?(c1, c2), do: String.upcase(<<c1::utf8>>) === String.upcase(<<c2::utf8>>)
|
|
def case_differs?(c1, c2), do: upcase?(c1) !== upcase?(c2)
|
|
def react?(c1, c2), do: same_letter?(c1, c2) && case_differs?(c1, c2)
|
|
|
|
# note: reverses the list - for part 1 doesn't seem to matter
|
|
def react(chars) do
|
|
Enum.reduce(chars, [], fn
|
|
curr, [] -> [curr]
|
|
curr, [prev | old] -> if react?(curr, prev), do: old, else: [curr, prev | old]
|
|
end)
|
|
end
|
|
|
|
def part1 do
|
|
File.read!("input")
|
|
|> String.trim()
|
|
|> String.to_charlist()
|
|
|> react()
|
|
|> length()
|
|
end
|
|
|
|
def part2 do
|
|
polymer =
|
|
File.read!("input")
|
|
|> String.trim()
|
|
|> String.to_charlist()
|
|
|
|
lengths =
|
|
for lower <- ?a..?z, upper = lower - 32 do
|
|
Enum.reject(polymer, &(&1 in [lower, upper]))
|
|
|> react()
|
|
|> length()
|
|
end
|
|
|
|
Enum.min(lengths)
|
|
end
|
|
end
|
|
|
|
IO.puts(Day5.part1())
|
|
IO.puts(Day5.part2())
|