2022 Day 4

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Adam Millerchip 2022-12-04 15:59:40 +09:00
parent afaacf77a1
commit 79b64b911d

55
2022/day4.exs Normal file
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defmodule Day4 do
def part1(input) do
Enum.count(input, fn [a, b] -> MapSet.subset?(a, b) or MapSet.subset?(b, a) end)
end
def part2(input) do
Enum.count(input, fn [a, b] -> not MapSet.disjoint?(a, b) end)
end
def input do
with [input_filename] <- System.argv(),
{:ok, input} <- File.read(input_filename) do
input
|> String.split(["-", ",", "\n"], trim: true)
|> Enum.map(&String.to_integer/1)
|> Enum.chunk_every(2)
|> Enum.map(fn [a, b] -> MapSet.new(a..b) end)
|> Enum.chunk_every(2)
else
_ -> :error
end
end
#######################
# HERE BE BOILERPLATE #
#######################
def run do
case input() do
:error -> print_usage()
input -> run_parts_with_timer(input)
end
end
defp run_parts_with_timer(input) do
run_with_timer(1, fn -> part1(input) end)
run_with_timer(2, fn -> part2(input) end)
end
defp run_with_timer(part, fun) do
{time, result} = :timer.tc(fun)
IO.puts("Part #{part} (completed in #{format_time(time)}):\n")
IO.puts("#{result}\n")
end
defp format_time(μsec) when μsec < 1_000, do: "#{μsec}μs"
defp format_time(μsec) when μsec < 1_000_000, do: "#{μsec / 1000}ms"
defp format_time(μsec), do: "#{μsec / 1_000_000}s"
defp print_usage do
IO.puts("Usage: elixir day4.exs input_filename")
end
end
Day4.run()