--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/scripts/ring.rb	Wed Jan 02 21:48:37 2019 +0900
@@ -0,0 +1,28 @@
+def create_nodes(node_num)
+  (0..node_num - 1).map { |i|
+    i = "node" + i.to_s
+  }
+end
+
+def print_dot(connections)
+  puts "digraph test {"
+  connections.each { |connection|
+    print "\t"
+    print connection[0]
+    print " -> "
+    print connection[1]
+    print ' [label="' + connection[2] + '"]'
+    puts
+  }
+  puts "}"
+end
+
+node_num = ARGV[0].to_i
+nodes = create_nodes(node_num)
+connections = Array.new
+nodes.each_with_index { |node, i|
+  connections << [nodes[i], nodes[(i + 1) % node_num], "right"]
+  connections << [nodes[i], nodes[i - 1], "left"]
+}
+print_dot(connections)
+