solution to 2.67

diff --git a/src/sicp/ex2_67.rkt b/src/sicp/ex2_67.rkt
new file mode 100644 (file)
index 0000000..a740f05
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+++ b/src/sicp/ex2_67.rkt
@@ -0,0 +1,15 @@
+#lang racket
+
+(require "ch2_3.rkt"
+         rackunit)
+
+;; Exercise 2.67.  Define an encoding tree and a sample message:
+(define sample-tree
+  (make-code-tree (make-leaf 'A 4)
+                  (make-code-tree 
+                   (make-leaf 'B 2)
+                   (make-code-tree (make-leaf 'D 1)
+                                   (make-leaf 'C 1)))))
+(define sample-message '(0 1 1 0 0 1 0 1 0 1 1 1 0))
+
+(check equal? (decode sample-message sample-tree) '(A D A B B C A))
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