Day 2: Red-Nosed Reports
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Elixir
defmodule AdventOfCode.Solution.Year2024.Day02 do
use AdventOfCode.Solution.SharedParse
@impl true
def parse(input) do
for line <- String.split(input, "\n", trim: true),
do: String.split(line) |> Enum.map(&String.to_integer/1)
end
def part1(input) do
Enum.count(input, &is_safe(&1, false))
end
def part2(input) do
Enum.count(input, &(is_safe(&1, true) or is_safe(tl(&1), false)))
end
def is_safe([a, b, c | rest], can_fix) do
cond do
(b - a) * (c - b) > 0 and abs(b - a) in 1..3 and abs(c - b) in 1..3 ->
is_safe([b, c | rest], can_fix)
can_fix ->
is_safe([a, c | rest], false) or is_safe([a, b | rest], false)
true ->
false
end
end
def is_safe(_, _), do: true
end