From 4a32c58221e6f1f5b885c09f60340911068c2b9d Mon Sep 17 00:00:00 2001
From: Jeremy Ashkenas <jashkenas@gmail.com>
Date: Sun, 17 Jan 2010 15:58:44 -0500
Subject: [PATCH] added bentley's chapter from beautiful code to the
 examples/tests -- quicksort runtime analysis

---
 examples/beautiful_code/quicksort.coffee            | 13 +++++++++++++
 .../regular_expression_matcher.coffee               |  4 ++--
 2 files changed, 15 insertions(+), 2 deletions(-)
 create mode 100644 examples/beautiful_code/quicksort.coffee

diff --git a/examples/beautiful_code/quicksort.coffee b/examples/beautiful_code/quicksort.coffee
new file mode 100644
index 00000000..bbba0504
--- /dev/null
+++ b/examples/beautiful_code/quicksort.coffee
@@ -0,0 +1,13 @@
+# Beautiful Code, Chapter 3.
+# Produces the expected runtime of Quicksort, for every integer from 1 to N.
+
+runtime: N =>
+  [sum, t]: [0, 0]
+  for n in [1..N]
+    sum += 2 * t
+    t: n - 1 + sum / n
+  t
+
+print(runtime(3) is 2.6666666666666665)
+print(runtime(5) is 7.4)
+print(runtime(8) is 16.92142857142857)
diff --git a/examples/beautiful_code/regular_expression_matcher.coffee b/examples/beautiful_code/regular_expression_matcher.coffee
index d36f1d30..da6bd696 100644
--- a/examples/beautiful_code/regular_expression_matcher.coffee
+++ b/examples/beautiful_code/regular_expression_matcher.coffee
@@ -1,5 +1,5 @@
-# Beautiful Code, chapter 1.
-# Implements a regular expression matcher that supports characters,
+# Beautiful Code, Chapter 1.
+# Implements a regular expression matcher that supports character matches,
 # '.', '^', '$', and '*'.
 
 # Search for the regexp anywhere in the text.