solution to 2.62

diff --git a/src/sicp/ex2_62.clj b/src/sicp/ex2_62.clj
new file mode 100644 (file)
index 0000000..0ca7117
--- /dev/null
+++ b/src/sicp/ex2_62.clj
@@ -0,0 +1,25 @@
+(ns sicp.ex2_62
+  (:use [clojure.test]))
+
+(defn union-set [set1 set2]
+  (let [x1 (first set1)
+        x2 (first set2)]
+    (cond (empty? set1) set2
+          (empty? set2) set1
+          (= x1 x2) (cons x1 (union-set (rest set1)
+                                        (rest set2)))
+          (< x1 x2) (cons x1 (union-set (rest set1)
+                                        set2))
+          (> x1 x2) (cons x2 (union-set set1
+                                        (rest set2))))))
+
+(deftest test-union
+  (are [x y] [= x y]
+       (union-set '() '()) '()
+       (union-set '(1) '()) '(1)
+       (union-set '() '(1)) '(1)
+       (union-set '(1 2 3) '(1 2 3)) '(1 2 3)
+       (union-set '(1 2 3 4) '(1 2 3)) '(1 2 3 4)
+       (union-set '(1 2 4) '(3 4 5)) '(1 2 3 4 5)
+       (union-set '(1 2 3 4) '(5 6 7 8)) '(1 2 3 4 5 6 7 8)
+       (union-set '(1 2 3) '(3 4 5 6)) '(1 2 3 4 5 6)))