tree を簡単に可視化する方法ないだろうかで教えていただいた graphviz を試してみた。 ツリーの構造を以下のようなファイルで指定する。 digraph rbtrees { 1 [style = filled, fillcolor = "#cccccc"]; "Nil0" [style = filled, fillcolor = "#cccccc"]; 1 -> "Nil0"; 2 [style = filled, color = "#336666", fillcolor = "#CC9999"]; 1 -> 2; 2 [style = filled, color = "#336666", fillcolor = "#CC9999"]; "Nil1" [style = filled, fillcolor = "#cccccc"]; 2 -> "Nil1"; 3 [style = f
![graphviz でツリー構造を可視化 - higepon blog](https://cdn-ak-scissors.b.st-hatena.com/image/square/e0bd470d871d715e22b666276f715f9968c2c3f4/height=288;version=1;width=512/https%3A%2F%2Fcdn-ak.f.st-hatena.com%2Fimages%2Ffotolife%2Fh%2Fhigepon%2F20100417%2F20100417210226.png)