Day 3
Mix.install([:kino])
Read Input
file_input = Kino.Input.file("Please Select Input File")
file_info = Kino.Input.read(file_input)
file_path = Kino.Input.file_path(file_info.file_ref)
contents = File.read!(file_path)
parse_mul = fn instruction ->
~r/mul\((?\d{1,3}),(?\d{1,3})\)/
|> Regex.named_captures(instruction)
|> Map.values()
|> Enum.map(&String.to_integer/1)
|> List.to_tuple()
end
Part 1
instructions = ~r/mul\(\d{1,3},\d{1,3}\)/
|> Regex.scan(contents)
|> Enum.reject(&Enum.empty?/1)
|> List.flatten()
|> Enum.map(&(parse_mul.(&1)))
|> Enum.reduce(0, fn({a, b}, sum) -> sum + (a * b) end)
Part 2
parse_instruction = fn
"do()" -> :include
"don't()" -> :exclude
instruction -> parse_mul.(instruction)
end
instructions = ~r/(mul\(\d{1,3},\d{1,3}\))|(do\(\))|(don't\(\))/
|> Regex.scan(contents)
|> Enum.map(&List.last/1)
|> Enum.map(&(parse_instruction.(&1)))
result = instructions
|> Enum.reduce({0, :include}, fn
({a, b}, {sum, :include}) -> {sum + (a * b), :include}
(mode, {sum, _}) -> {sum, mode}
end)
|> elem(0)
