AdventOfCode/2020/elixir/day4/day4part2.exs

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Elixir
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defmodule Day4Part2 do
@required MapSet.new(["byr", "ecl", "eyr", "hcl", "hgt", "iyr", "pid"])
def run do
File.read!("input")
|> String.trim()
|> String.split("\n\n")
|> Enum.map(fn passport ->
passport
|> String.split([" ", "\n"])
|> Enum.map(&String.split(&1, ":"))
|> Map.new(fn [k, v] -> {k, v} end)
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|> Map.delete("cid")
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end)
|> Enum.filter(&MapSet.subset?(@required, &1 |> Map.keys() |> MapSet.new()))
|> Enum.count(&valid?/1)
|> IO.puts()
end
def valid?(passport) do
byr?(passport) && iyr?(passport) && eyr?(passport) && hgt?(passport) && hcl?(passport) &&
ecl?(passport) && pid?(passport)
end
def byr?(%{"byr" => byr}) do
date = String.to_integer(byr)
1920 <= date && date <= 2002
end
def iyr?(%{"iyr" => iyr}) do
date = String.to_integer(iyr)
2010 <= date && date <= 2020
end
def eyr?(%{"eyr" => eyr}) do
date = String.to_integer(eyr)
2020 <= date && date <= 2030
end
def hgt?(%{"hgt" => hgt}) do
{hgt, unit} =
case Regex.run(~r/\A(\d+)([^\d]+)\z/, hgt, capture: :all_but_first) do
[hgt, unit] -> {String.to_integer(hgt), unit}
nil -> {0, nil}
end
case unit do
"cm" -> 150 <= hgt && hgt <= 193
"in" -> 59 <= hgt && hgt <= 76
nil -> false
end
end
def hcl?(%{"hcl" => hcl}) do
Regex.match?(~r/\A#[0-9a-f]{6}\z/, hcl)
end
def ecl?(%{"ecl" => ecl}) do
ecl in ["amb", "blu", "brn", "gry", "grn", "hzl", "oth"]
end
def pid?(%{"pid" => pid}) do
Regex.match?(~r/\A\d{9}\z/, pid)
end
end
Day4Part2.run()