Ch148 (Clojure): Task #2

2 files changed, 44 insertions, 0 deletions

diff --git a/challenge-148/tyler-wardhaugh/clojure/src/c148/t2.clj b/challenge-148/tyler-wardhaugh/clojure/src/c148/t2.clj
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index 0000000000..146d377ebc
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+++ b/challenge-148/tyler-wardhaugh/clojure/src/c148/t2.clj
@@ -0,0 +1,30 @@
+(ns c148.t2
+  (:require [clojure.math :as m]
+            [clojure.pprint :refer [cl-format]]))
+
+;(set! *warn-on-reflection* true)
+(def DEFAULT-EPS 1e-6)
+(def MAX 100)
+
+(defn one-ish?
+  ([n] (one-ish? n DEFAULT-EPS))
+  ([n eps] (< (abs (- 1.0 n)) eps)))
+
+; equivalent formula, found at: https://math.stackexchange.com/a/1885139
+(defn cardano-triplet?
+  [a b c]
+  (one-ish? (- (+ (* 8 (m/pow a 3)) 
+                  (* 15 (m/pow a 2))
+                  (* 6 a))
+               (* 27 (m/pow b 2) c))))
+
+(def cardano-triplets
+  (for [a (range MAX)
+        b (range MAX)
+        c (range MAX)
+        :when (cardano-triplet? a b c)]
+    [a b c]))
+
+(defn -main
+  [& _]
+  (cl-format true "~{(~{~a~^, ~})~%~}" (take 5 cardano-triplets)))
diff --git a/challenge-148/tyler-wardhaugh/clojure/test/c148/t2_test.clj b/challenge-148/tyler-wardhaugh/clojure/test/c148/t2_test.clj
new file mode 100644
index 0000000000..37830d6b3e
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+++ b/challenge-148/tyler-wardhaugh/clojure/test/c148/t2_test.clj
@@ -0,0 +1,14 @@
+(ns c148.t2-test
+  (:require [clojure.test :refer [deftest is testing]]
+            [c148.t2 :refer [cardano-triplets]]))
+
+(def FIRST-FIVE-CARDANO-TRIPLETS 
+  [[2 1 5]
+   [5 1 52]
+   [5 2 13]
+   [8 3 21]
+   [11 4 29]])
+
+(deftest target
+  (testing "Target identified in task description"
+    (is (= FIRST-FIVE-CARDANO-TRIPLETS (take 5 cardano-triplets)))))