Add q67

src/ex/q066.clj

@@ -8,7 +8,8 @@
   (some #(when (= 0 (rem x %) (rem y %)) %) (range (min x y) 0 -1)))
 
 (defn ans2
-  "Problem 66, using Euclid's algorithm (https://en.wikipedia.org/wiki/Greatest_common_divisor#Euclid's_algorithm)"
+  "Problem 66, using Euclid's algorithm,
+  https://en.wikipedia.org/wiki/Greatest_common_divisor#Euclid's_algorithm"
   [x y]
   (loop [x x y y]
     (if (= x y) x (recur (- (max x y) (min x y)) (min x y)))))

src/ex/q067.clj

@@ -0,0 +1,14 @@
+;; https://4clojure.oxal.org/#/problem/067
+
+(ns ex.q067)
+
+(defn ans
+  "Problem 67, Prime Numbers"
+  [y]
+  (letfn [(prime? [x]
+            (cond
+              (< x 2) false
+              (= x 2) true
+              (even? x) false
+              :else (not-any? zero? (map #(mod x %) (range 3 (inc (Math/sqrt x)) 2)))))]
+    (take y (filter prime? (range)))))

test/ex/q067_test.clj

@@ -0,0 +1,11 @@
+;; https://4clojure.oxal.org/#/problem/067
+
+(ns ex.q067-test
+  (:require [clojure.test :as t]
+            [ex.q067 :as sut]))
+
+(t/deftest test-q67
+  (t/testing "Problem 67, Prime Numbers"
+    (t/is (= [2 3] (sut/ans 2)))
+    (t/is (= [2 3 5 7 11] (sut/ans 5)))
+    (t/is (= 541 (last (sut/ans 100))))))