Mercurial > repos > other > adventofcode2023
view day11b.rb @ 27:6b58ddfaed38
Add Day 18 part 1 solution using line crossing
author | IBBoard <dev@ibboard.co.uk> |
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date | Tue, 02 Jan 2024 16:04:33 +0000 |
parents | ddb69833346c |
children |
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#! /usr/bin/env ruby 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] OPEN_SPACE = "." GALAXY = "#" EXPANSION_FACTOR = 1000000 input_space = File.open(file, "r").each_line(chomp: true).map(&:each_char).map(&:to_a) first, *rest = input_space open_columns = first.zip(*rest).each_with_index.map {|col, idx| col.all? {|cell| cell == OPEN_SPACE} ? idx : nil}.compact open_rows = input_space.each_with_index.map {|row, idx| row.all? {|cell| cell == OPEN_SPACE} ? idx : nil}.compact galaxies = input_space.each_with_index.flat_map {|row, y| row.each_with_index.map {|cell, x| [x, y] if cell == GALAXY}}.compact galactic_distances = galaxies.combination(2).map do |a, b| x_1, x_2 = [a[0], b[0]].minmax y_1, y_2 = [a[1], b[1]].minmax expanded_cols = ((x_1..x_2).to_a & open_columns).length expanded_rows = ((y_1..y_2).to_a & open_rows).length # Avoid double-counting the expanded cell by subtracting the number of columns first rather any complex logic x_2 - x_1 + - expanded_cols + (expanded_cols * EXPANSION_FACTOR) + y_2 - y_1 + - expanded_rows + (expanded_rows * EXPANSION_FACTOR) end puts galactic_distances.sum