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December 20, 2023 00:28
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Advent of Code 2023 day019.rb
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require_relative "main" | |
module Day019 | |
INPUT = File.read('INPUT.txt') | |
parts = INPUT.split("\n\n") | |
guides = parts.first.to_lines.map do |guide_line| | |
guide_pieces = guide_line.split("{") | |
name = guide_pieces.first | |
predicates = guide_pieces.last[0..(guide_pieces.last.length - 2)].split(",").map do |predicate| | |
predicate_parts = predicate.split(":") | |
if predicate_parts.count == 2 | |
cond_text = predicate_parts.first | |
parts_gt = predicate_parts.first.split(">") | |
parts_lt = predicate_parts.first.split("<") | |
if parts_gt.count == 2 | |
cond = ->(part) { part[parts_gt.first] > parts_gt.last.to_i } | |
elsif parts_lt.count == 2 | |
cond = ->(part) { part[parts_lt.first] < parts_lt.last.to_i } | |
else | |
raise "wat" | |
end | |
dest = predicate_parts.last | |
else | |
cond_text = "true" | |
cond = ->(_) { true } | |
dest = predicate | |
end | |
{ | |
cond_text: cond_text, | |
cond: cond, | |
dest: dest | |
} | |
end | |
[name, predicates] | |
end.to_h | |
parts = parts.last.to_lines.map do |part_text| | |
part_text.gsub(/[\{\}]/, "").split(",").map do |item| | |
k, v = item.split("=") | |
[k, v.to_i] | |
end.to_h | |
end | |
########## | |
# Part 1 # | |
########## | |
is_accepted = ->(part) do | |
guide_name = "in" | |
loop do | |
if guide_name == "A" | |
return true | |
elsif guide_name == "R" | |
return false | |
else | |
guide = guides[guide_name] | |
guide.each do |predicate| | |
if predicate[:cond].call(part) | |
guide_name = predicate[:dest] | |
break | |
end | |
end | |
end | |
end | |
end | |
answer1 = parts.reduce(0) do |memo, part| | |
is_accepted.call(part) ? memo + part.values.sum : memo | |
end | |
pp answer1 | |
########## | |
# Part 2 # | |
########## | |
MAX = 4000 | |
all_acceptances = [] | |
dfs = ->(cursor, ranges) do | |
return if cursor == "R" | |
if cursor == "A" | |
all_acceptances.push(ranges) | |
else | |
next_ranges = ranges.clone | |
last_ranges = next_ranges.clone | |
guides[cursor].each do |predicate| | |
parts_gt = predicate[:cond_text].split(">") | |
parts_lt = predicate[:cond_text].split("<") | |
if parts_gt.count == 2 | |
char = parts_gt.first | |
ranges_new = ((parts_gt.last.to_i + 1)..MAX).to_a & next_ranges[char] | |
next_ranges[char] = ranges_new | |
elsif parts_lt.count == 2 | |
char = parts_lt.first | |
ranges_new = (1..(parts_lt.last.to_i - 1)).to_a & next_ranges[char] | |
next_ranges[char] = ranges_new | |
end | |
dfs.call(predicate[:dest], next_ranges) | |
next_ranges = next_ranges.map do |k, v| | |
if last_ranges[k] != v | |
[k, last_ranges[k] - v] | |
else | |
[k, v] | |
end | |
end.to_h | |
last_ranges = next_ranges.clone | |
end | |
end | |
end | |
dfs.call("in", { | |
"x" => (1..MAX).to_a, | |
"m" => (1..MAX).to_a, | |
"a" => (1..MAX).to_a, | |
"s" => (1..MAX).to_a | |
}) | |
answer2 = all_acceptances.reduce(0) do |memo, range| | |
memo + range.values.map(&:count).arith_prod | |
end | |
pp answer2 | |
end |
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