Day 1: two solutions for part one, part two + tests. Would love to hear some critic/thoughts/suggestions.
defmodule AOC_2021.Day1 do
@input "input.txt"
def part_one_1 do
[_, result] =
@input
|> list_of_numbers()
|> Enum.reduce([0, 0], fn item, [last_item, result] ->
cond do
last_item == 0 ->
[item, result]
last_item < item ->
[item, result + 1]
true ->
[item, result]
end
end)
result
end
def part_one_2 do
result =
@input
|> list_of_numbers()
|> Enum.to_list()
|> do_job(0)
result
end
defp do_job([first | [second | _] = tail], result) when first < second,
do: do_job(tail, result + 1)
defp do_job([_ | [_ | _] = tail], result), do: do_job(tail, result)
defp do_job([_ | _], result), do: result
def part_two do
[_item, _, result] =
@input
|> list_of_numbers()
|> Enum.chunk_every(3, 1, :discard)
|> Enum.reduce([0, 0, 0], fn [first, second, third], [last_item, window_sum, result] ->
cond do
last_item == 0 ->
[first + second + third, second + third, result]
last_item < window_sum + third ->
[window_sum + third, second + third, result + 1]
true ->
[window_sum + third, second + third, result]
end
end)
result
end
defp list_of_numbers(input) do
input
|> File.stream!([], :line)
|> Stream.map(fn line ->
{integer, _} = Integer.parse(line)
integer
end)
end
end
case System.argv() do
["--test"] ->
ExUnit.start()
defmodule AOC_2021.Day1Test do
use ExUnit.Case
@expected_part_one 1121
@expected_part_two 1065
test "tests" do
response = fn _, _, _ ->
[
AOC_2021.Day1.part_one_1(),
AOC_2021.Day1.part_one_2(),
AOC_2021.Day1.part_two()
]
end
assert [@expected_part_one, @expected_part_one, @expected_part_two] ==
response.(1121, 1121, 1065)
end
end
["--run"] ->
AOC_2021.Day1.part_one_1()
|> IO.inspect(label: "\npart_one_1 \n")
AOC_2021.Day1.part_one_2()
|> IO.inspect(label: "\npart_one_2 \n")
AOC_2021.Day1.part_two()
|> IO.inspect(label: "\npart_two \n")
_ ->
IO.puts(:stderr, "\nplease specify --run or --test flag")
end
