Mercurial > repos > other > adventofcode2023
view day22.rb @ 35:ca54f9702892
Day 24 part 2 instructions and partial solution
author | IBBoard <dev@ibboard.co.uk> |
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date | Thu, 18 Apr 2024 19:54:59 +0100 |
parents | 47dc75915e91 |
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] Block = Struct.new(:id, :x, :y, :z) SupportedBy = Struct.new(:blocks, :z) supports = Hash.new supported_by = Hash.new blocks = File.open(file, "r").each_line(chomp: true).with_index.map do |line, id| block_start, block_end = line.split("~") start_x, start_y, start_z = block_start.split(",") end_x, end_y, end_z = block_end.split(",") supports[id] = [] Block.new(id, start_x.to_i..end_x.to_i, start_y.to_i..end_y.to_i, start_z.to_i..end_z.to_i) end def height_sort(a,b) if a.z.first == b.z.first # Make it a stable sort a.y.first == b.y.first ? a.x.first <=> b.x.first : a.y.first <=> b.y.first else a.z.first <=> b.z.first end end blocks.sort! {|a,b| height_sort(a, b)} def overlap?(range_1, range_2) range_1.include?(range_2.first) || range_1.include?(range_2.last) || range_2.include?(range_1.first) || range_2.include?(range_1.last) end blocks.reduce([]) do |lower_blocks, block| support_blocks = lower_blocks.reduce(SupportedBy.new([], 0)) do |candidate_supports, lower_block| if overlap?(block.x, lower_block.x) && overlap?(block.y, lower_block.y) if lower_block.z.last > candidate_supports.z SupportedBy.new([lower_block], lower_block.z.last) elsif lower_block.z.last == candidate_supports.z candidate_supports.blocks << lower_block candidate_supports else candidate_supports end else candidate_supports end end drop = block.z.first - support_blocks.z - 1 block.z = (support_blocks.z+1)..(support_blocks.z+block.z.size) support_blocks.blocks.each {|support| supports[support.id] << block} supported_by[block.id] = support_blocks.blocks lower_blocks << block lower_blocks end disintegratable = supports.filter {|block_id, supports_list| supports_list.all? {|supported| supported_by[supported.id].length > 1} } puts "#{disintegratable.length} disintegratable blocks" def find_droppers(id, supports, supported_by, dropping, cache) new_drops = supports[id].filter do |block| (Set.new(supported_by[block.id].map(&:id)) - dropping).length == 0 end dropping = dropping + new_drops.map(&:id) new_drops.each do |supported_block| cache_key = [supported_block.id, Set.new(supported_by[supported_block.id].map(&:id)) & dropping] if cache.include?(cache_key) dropping += cache[cache_key] #puts "Got #{cache[cache_key]} for #{cache_key}" else supported_droppers = find_droppers(supported_block.id, supports, supported_by, dropping, cache) cache[cache_key] = supported_droppers #puts "Caching #{supported_droppers} for #{cache_key} while dropping #{dropping}" dropping += supported_droppers end end dropping - [id] end cascade = Hash.new cache = Hash.new blocks.reverse.each do |block| id = block.id cascade[id] = find_droppers(id, supports, supported_by, Set.new([id]), cache) end puts "Dropping a total of #{cascade.values.map{|val| val.length}.sum} blocks"