Solve AOC2025 day 5 part 2 in Ruby

Author: daniero

aoc2025/input-sample05.txt

@@ -0,0 +1,11 @@
+3-5
+10-14
+16-20
+12-18
+
+1
+5
+8
+11
+17
+32

aoc2025/ruby/05.rb

@@ -1,8 +1,29 @@
 a,b = File
-  .read('../input-real05.txt')
+  .read('input-05.txt')
   .split("\n\n")
 
-ranges = a.lines.map { it.scan(/\d+/).map(&:to_i).then { Range.new *it } }
+ranges = a.lines.map { Range.new *it.scan(/\d+/).map(&:to_i) }
 ids = b.lines.map(&:to_i)
 
-p ids.count { |id| ranges.any? { |range| range.cover? id } }
+
+print "Part 1: "
+puts ids.count { |id| ranges.any? { |range| range.cover? id } }
+
+
+print "Part 2: "
+
+without_overlap = ranges
+  .sort_by { [it.min, -it.size] }
+  .reduce([]) { |rs, r|
+    next [r] if rs.empty?
+    next rs if rs.last.cover? r
+    next rs if r.min < rs.last.min && r.max <= rs.last.max
+
+    start = [r.min, rs.last.max+1].max
+    next_range = Range.new(start, r.max)
+    next rs if rs.last.cover? next_range
+
+    [*rs, next_range]
+  }
+
+puts without_overlap.sum { it.size }