[2024][ruby][6.x] optimize obstacles

2024/ruby/day_06.rb

@@ -44,10 +44,11 @@ rescue Loop
   true
 end
 
-pp patrol(input).map(&:first).to_set.length
+path = patrol(input).map(&:first).to_set
+pp path.length
 
 pp input
-  .select { _2 == ?. }
+  .select { path.include?(_1) && _2 != ?^ }
   .select {|xy, _|
     # pp xy
     input[xy] = ?#