Initial data commit

Task/Proper-divisors/Clojure/proper-divisors.clj

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+(ns properdivisors
+  (:gen-class))
+
+(defn proper-divisors [n]
+  " Proper divisors of n"
+  (if (= n 1)
+    []
+  (filter #(= 0 (rem n %)) (range 1 n))))
+
+;; Property divisors of numbers 1 to 20,000 inclusive
+(def data (for [n (range 1 (inc 20000))]
+            [n (proper-divisors n)]))
+
+;; Find Max
+(defn maximal-key [k x & xs]
+  " Normal max-key only finds one key that produces maximum, while this function finds them all "
+  (reduce (fn [ys x]
+            (let [c (compare (k x) (k (peek ys)))]
+              (cond
+                (pos? c) [x]
+                (neg? c) ys
+                :else    (conj ys x))))
+          [x]
+          xs))
+
+(println "n\tcnt\tPROPER DIVISORS")
+(doseq [n (range 1 11)]
+  (let [factors (proper-divisors n)]
+    (println n "\t" (count factors) "\t" factors)))
+
+(def max-data (apply maximal-key (fn [[i pd]] (count pd)) data))
+
+(doseq [[n factors] max-data]
+  (println n " has " (count factors) " divisors"))