--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/scripts/tree.rb	Wed Feb 07 19:31:33 2018 +0900
@@ -0,0 +1,38 @@
+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|
+  parent = (i - 1) / 2;
+  child1 = 2 * i + 1;
+  child2 = 2 * i + 2;
+  if parent >= 0 then
+    connections << [nodes[i], nodes[parent], "parent"]
+  end
+  if child1 < node_num then
+    connections << [nodes[i], nodes[child1], "child1"]
+  end
+  if child2 < node_num then
+    connections << [nodes[i], nodes[child2], "child2"]
+  end
+}
+print_dot(connections)
+