72 lines
1.6 KiB
Elixir
72 lines
1.6 KiB
Elixir
|
defmodule Day3 do
|
||
|
|
def part1(input) do
|
||
|
|
input
|
||
|
|
|> Enum.map(fn str ->
|
||
|
|
size = byte_size(str)
|
||
|
|
|
||
|
|
str
|
||
|
|
|> String.split("", trim: true)
|
||
|
|
|> Enum.split(div(size, 2))
|
||
|
|
end)
|
||
|
|
|> Enum.map(fn {a, b} -> hd(a -- a -- b) end)
|
||
|
|
|> Enum.map(&score/1)
|
||
|
|
|> Enum.sum()
|
||
|
|
end
|
||
|
|
|
||
|
|
defp score(<<lower::utf8>>) when lower in ?a..?z, do: lower - ?a + 1
|
||
|
|
defp score(<<upper::utf8>>) when upper in ?A..?Z, do: upper - ?A + 27
|
||
|
|
|
||
|
|
def part2(input) do
|
||
|
|
input
|
||
|
|
|> Enum.map(&String.split(&1, "", trim: true))
|
||
|
|
|> Enum.chunk_every(3)
|
||
|
|
|> Enum.map(fn [a, b, c] ->
|
||
|
|
d = a -- a -- b
|
||
|
|
hd(d -- d -- c)
|
||
|
|
end)
|
||
|
|
|> Enum.map(&score/1)
|
||
|
|
|> Enum.sum()
|
||
|
|
end
|
||
|
|
|
||
|
|
def input do
|
||
|
|
with [input_filename] <- System.argv(),
|
||
|
|
{:ok, input} <- File.read(input_filename) do
|
||
|
|
String.split(input, "\n", trim: true)
|
||
|
|
else
|
||
|
|
_ -> :error
|
||
|
|
end
|
||
|
|
end
|
||
|
|
|
||
|
|
#######################
|
||
|
|
# HERE BE BOILERPLATE #
|
||
|
|
#######################
|
||
|
|
|
||
|
|
def run do
|
||
|
|
case input() do
|
||
|
|
:error -> print_usage()
|
||
|
|
input -> run_parts_with_timer(input)
|
||
|
|
end
|
||
|
|
end
|
||
|
|
|
||
|
|
defp run_parts_with_timer(input) do
|
||
|
|
run_with_timer(1, fn -> part1(input) end)
|
||
|
|
run_with_timer(2, fn -> part2(input) end)
|
||
|
|
end
|
||
|
|
|
||
|
|
defp run_with_timer(part, fun) do
|
||
|
|
{time, result} = :timer.tc(fun)
|
||
|
|
IO.puts("Part #{part} (completed in #{format_time(time)}):\n")
|
||
|
|
IO.puts("#{result}\n")
|
||
|
|
end
|
||
|
|
|
||
|
|
defp format_time(μsec) when μsec < 1_000, do: "#{μsec}μs"
|
||
|
|
defp format_time(μsec) when μsec < 1_000_000, do: "#{μsec / 1000}ms"
|
||
|
|
defp format_time(μsec), do: "#{μsec / 1_000_000}s"
|
||
|
|
|
||
|
|
defp print_usage do
|
||
|
|
IO.puts("Usage: elixir day3.exs input_filename")
|
||
|
|
end
|
||
|
|
end
|
||
|
|
|
||
|
|
Day3.run()
|