aoc/2020/lib/days/day2.ex

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Elixir
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2023-04-17 18:18:20 +00:00
defmodule AOC.Day2 do
def parse_line(line) do
[min, max, char, password] = String.split(line, [" ", "-", ":"], trim: true)
password = String.to_charlist(password)
[char] = String.to_charlist(char)
min = String.to_integer(min)
max = String.to_integer(max)
[password, char, min, max]
end
def validate_password1(password, char, min, max) do
count = Enum.count(password, &(&1 == char))
count in min..max
end
def part1 do
AOC.Util.input_lines(2, 1)
|> Enum.map(&parse_line/1)
|> Enum.map(&apply(__MODULE__, :validate_password1, &1))
|> Enum.count(&Function.identity/1)
end
def validate_password2(password, char, pos1, pos2) do
m1 = Enum.at(password, pos1 - 1) == char
m2 = Enum.at(password, pos2 - 1) == char
(m1 or m2) and not (m1 and m2)
end
def part2 do
AOC.Util.input_lines(2, 1)
|> Enum.map(&parse_line/1)
|> Enum.map(&apply(__MODULE__, :validate_password2, &1))
|> Enum.count(&Function.identity/1)
end
end