[2024][ruby][6.x] refactor

2024/ruby/day_06.rb

@@ -15,25 +15,29 @@ TURNS = {
 Loop = Class.new(Exception)
 
 def patrol(lab)
+  return enum_for(__method__, lab) unless block_given?
+
   start = lab.find { _2 == ?^ }.first
-  path = [[start, [-1,0]]]
-  seen = path.to_set
+  guard = [start, [-1,0]]
+  seen = Set.new
+
   loop do
-    pos, dir = path.last
-    peek = pos.zip(dir).map {|i,di| i + di }
+    pos, dir = guard
+    yield pos
 
-    return path unless lab.has_key?(peek)
+    peek = pos.zip(dir).map {|i,di| i + di }
+    return unless lab.has_key?(peek)
 
     raise Loop if seen.include?([peek, dir])
     seen << [peek, dir]
 
     case lab.fetch(peek)
     when ?., ?^
-      path << [peek, dir]
+      guard[0] = peek
     when ?#
-      path.last[1] = TURNS.fetch(dir)
+      guard[1] = TURNS.fetch(dir)
     when nil
-      return path
+      return
     else
       fail
     end
@@ -41,13 +45,13 @@ def patrol(lab)
 end
 
 def loop?(lab)
-  patrol(lab)
+  patrol(lab).each {}
   false
 rescue Loop
   true
 end
 
-path = patrol(input).map(&:first).to_set
+path = patrol(input).to_set
 pp path.length
 
 pp input