1 files changed, 52 insertions, 0 deletions
diff --git a/coding-exercises/2/66.rkt b/coding-exercises/2/66.rkt
new file mode 100644
index 0000000..7cfedb8
--- /dev/null
+++ b/coding-exercises/2/66.rkt
@@ -0,0 +1,52 @@
+#lang racket
+(require "../../shared/sets.rkt")
+
+;; just use id as key
+(define (key x)
+  (if (number? x)
+    x
+    (error "Only supports numericals that we can compare with >, <, = -- KEY")))
+
+(define (list-lookup given-key set-of-records)
+  (cond ((null? set-of-records) false)
+        ((equal? given-key (key (car set-of-records)))
+         (car set-of-records))
+        (else (list-lookup given-key (cdr set-of-records)))))
+
+(define (lookup given-key set-of-records)
+  (if (null? set-of-records) 
+    false
+    (let ((v (key (car set-of-records))))
+      (cond ((= given-key v) v)
+            ((< given-key v)
+             (lookup given-key (left-branch set-of-records)))
+            ((> given-key v)
+             (lookup given-key (right-branch set-of-records)))))))
+
+((lambda ()
+  (println "list -- LOOKUP")
+  (println (list-lookup 5 (list 1 2 3 4 5)))
+  (newline)
+  (println "tree -- UNION")
+  (define test216a (make-entry
+                     7
+                     '()
+                     '()))
+  (define test216b (make-entry
+                     4
+                     (make-entry 1 '() '())
+                     (make-entry
+                       8
+                       (make-entry 6 '() '())
+                       (make-entry
+                         10
+                         '()
+                         (make-entry
+                                       12
+                                       '()
+                                       '())))))
+  (println (lookup 10
+                   (union-set
+                     (list->tree (tree->list test216a))
+                     (list->tree (tree->list test216b)))))
+  (newline)))