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defmodule Day02 do
def parse_report(line) do
line
|> String.trim()
|> String.split(" ")
|> Enum.map(&String.to_integer/1)
end
def is_report_safe(report) do
diffs = report
|> Enum.chunk_every(2, 1, :discard)
|> Enum.map(fn [a, b] -> b - a end)
Enum.all?(diffs, fn x -> 1 <= x and x <= 3 end) or
Enum.all?(diffs, fn x -> -3 <= x and x <= -1 end)
end
def is_report_safe_with_dampener(report) do
is_report_safe(report) or
Enum.any?(0..Enum.count(report)-1,
fn i -> List.delete_at(report, i) |> is_report_safe() end)
end
end
reports = IO.stream(:stdio, :line)
|> Enum.map(&Day02.parse_report/1)
ans1 = reports
|> Enum.count(&Day02.is_report_safe/1)
IO.puts(ans1)
ans2 = reports
|> Enum.count(&Day02.is_report_safe_with_dampener/1)
IO.puts(ans2)
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