[2023][ruby][8.1]

2023/ruby/day_08.rb

@@ -0,0 +1,14 @@
+instructions, network = ARGF.read.split("\n\n")
+
+network = network
+  .scan(/(\w+) = \((\w+), (\w+)\)/)
+  .to_h { [_1, { L: _2, R: _3 }] }
+
+node = "AAA"
+p instructions.chars.map(&:to_sym)
+  .cycle.with_index.lazy
+  .filter_map {|dir, i|
+    node = network.fetch(node).fetch(dir)
+    (node == "ZZZ") ? i+1 : nil
+  }
+  .first