Here’s my take:
defmodule Sol do
@file_path Path.join(~w(priv input.txt))
def run_1(file \\ @file_path) do
file
|> prepare_stream()
|> count(&increase?/2)
end
def run_2(file \\ @file_path) do
file
|> prepare_stream()
|> to_sliding_window()
|> Stream.map(&sum_window/1)
|> count(&increase?/2)
end
defp prepare_stream(file) do
file
|> File.stream!()
|> Stream.map(&String.trim/1)
|> Stream.map(&String.to_integer/1)
end
defp to_sliding_window(stream, size \\ 3) do
Stream.chunk_every(stream, size, 1, :discard)
end
defp sum_window(numbers) when length(numbers) == 3, do: Enum.sum(numbers)
defp count(stream, condition) do
{_, count} =
Enum.reduce(stream, {nil, 0}, fn val, {prev, count} ->
count =
case condition.(prev, val) do
true -> count + 1
false -> count
end
{val, count}
end)
count
end
defp increase?(prev, curr)
when is_integer(prev) and
is_integer(curr) and
prev < curr do
true
end
defp increase?(_, _), do: false
end
