Day five

5-1.rb

@@ -0,0 +1,47 @@
+#!/usr/bin/env ruby
+
+problem = 5
+input = File.readlines("#{problem}.input").map(&:strip)
+#input = DATA.read.split("\n")
+split = input.index("")
+
+rules = input[0...split].map { _1.split("|").map(&:to_i) }
+page_sets = input[split+1..].map { _1.split(",").map(&:to_i) }
+
+result = page_sets.select do |page_set|
+  rules
+    .select { |a| (page_set & a).sort == a.sort }
+    .all? { |(a, b)| page_set.index(a) < page_set.index(b) }
+end.map { _1[_1.size / 2] }.sum
+
+p result
+
+__END__
+47|53
+97|13
+97|61
+97|47
+75|29
+61|13
+75|53
+29|13
+97|29
+53|29
+61|53
+97|53
+61|29
+47|13
+75|47
+97|75
+47|61
+75|61
+47|29
+75|13
+53|13
+
+75,47,61,53,29
+97,61,53,29,13
+75,29,13
+75,97,47,61,53
+61,13,29
+97,13,75,29,47

5-2.rb

@@ -0,0 +1,61 @@
+#!/usr/bin/env ruby
+
+problem = 5
+input = File.readlines("#{problem}.input").map(&:strip)
+#input = DATA.read.split("\n")
+split = input.index("")
+
+rules = input[0...split].map { _1.split("|").map(&:to_i) }
+page_sets = input[split+1..].map { _1.split(",").map(&:to_i) }
+
+result = page_sets.select do |page_set|
+  rules
+    .select { |a| (page_set & a).sort == a.sort }
+    .any? { |(a, b)| page_set.index(a) > page_set.index(b) }
+end.map do |page_set|
+  matched_rules = rules
+    .select { |a| (page_set & a).sort == a.sort }
+    .reduce(Hash.new { |h, k| h[k] = Array.new }) { |a, (k, v)| a[k] << v; a }
+
+  page_set.sort do |a, b|
+    if matched_rules[a].include?(b)
+      -1
+    elsif matched_rules[b].include?(a)
+      1
+    else
+      0
+    end
+  end
+end.map { _1[_1.size / 2] }.sum
+
+p result
+
+__END__
+47|53
+97|13
+97|61
+97|47
+75|29
+61|13
+75|53
+29|13
+97|29
+53|29
+61|53
+97|53
+61|29
+47|13
+75|47
+97|75
+47|61
+75|61
+47|29
+75|13
+53|13
+
+75,47,61,53,29
+97,61,53,29,13
+75,29,13
+75,97,47,61,53
+61,13,29
+97,13,75,29,47