Sync

Task/Self-referential-sequence/Clojure/self-referential-sequence-2.clj

@@ -0,0 +1,19 @@
+(defn perms
+  "produce all the permutations of a finite sequence"
+  [ds]
+  (if (empty? ds)
+    []
+    (let [rotseq (for [n (range (count ds))] (concat (drop n ds) (take n ds)))]
+      (reduce-with [rs [], [[d & ds]] rotseq]
+        (concat rs (if (empty? ds) [[d]] (map #(cons d %) (perms ds))))))))
+
+(doseq [result results]
+  (let [seed (first result)
+        seeds (->> seed perms (map vec) set sort (remove (comp zero? first)))]
+    (apply println "Seed value(s):" (map #(apply str %) seeds)))))
+  (println)
+  (println "Iterations:" (count result))
+  (println)
+  (println "Sequence:")
+  (doseq [ds result]
+    (println (apply str ds))))