Mercurial > repos > other > adventofcode2023
view day4.rb @ 18:ddb69833346c
Implement day 11 distance finding in space
"shortest distance" is simplified by it being cardinal directions,
so it's the same as taking the right-angle between them.
The Part 1 space expansion was quite clean, but the Part 2
approach generalises it to something even nicer.
author | IBBoard <dev@ibboard.co.uk> |
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date | Mon, 11 Dec 2023 20:08:47 +0000 |
parents | 9da7a71b313d |
children |
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#! /usr/bin/env ruby require 'set' if ARGV.length != 1 abort("Incorrect arguments - needs input file") elsif not File.exist? (ARGV[0]) abort("File #{ARGV[0]} did not exist") end file = ARGV[0] sum = 0 File.open(file, "r").each_line(chomp: true) do |line| winning_number_str, our_number_str = line.split(":")[1].split("|").map(&:chomp) winning_numbers = Set.new(winning_number_str.split(" ").map(&:to_i)) our_numbers = Set.new(our_number_str.split(" ").map(&:to_i)) our_winning_numbers = winning_numbers & our_numbers sum += our_winning_numbers.length > 0 ? 2 ** (our_winning_numbers.length - 1) : 0 end puts sum