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Add alternative Day 5 parsing solution (to README)

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Adam Millerchip 2020-12-06 01:48:26 +09:00
parent ae2e69fb8e
commit d2dc8fb98c
1 changed files with 16 additions and 0 deletions
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@ -42,3 +42,19 @@ Did a lot of refactoring here but the end result, especially for part 2, is pret
Even if I decided to refactor the parser, it can just be swapped in for part 2. Zipping was a nice idea. Even if I decided to refactor the parser, it can just be swapped in for part 2. Zipping was a nice idea.
I quite enjoyed this one, maybe because it's a Saturday and I wasn't burnt out from work :-) I quite enjoyed this one, maybe because it's a Saturday and I wasn't burnt out from work :-)
** Update **
After reading the Elixir Forum thread: https://elixirforum.com/t/advent-of-code-2020-day-5/35997/
I really had to have a go at just parsing the boarding pass directly into an integer. I said I wouldn't
commit code to my solutions after reading forums, so I'll add it here instead :-) It converts each
character to a bit on the fly, and interprets the result as a 10-bit integer. 🦾
def char_to_bit(c) when c in 'FL', do: <<0::1>>
def char_to_bit(c) when c in 'BR', do: <<1::1>>
def seat_id_bitstring(boarding_pass \\ "FBFBBFFRLR") do
<<id::integer-10>> = for <<char <- boarding_pass>>, into: <<>>, do: char_to_bit(char)
id
end