lotto.clj

;; A Clojure implementation of http://koziolekweb.pl/2016/05/08/lotto-to-fajna-rzecz/.

(ns lotto)

(defn lotto
  ([] (lotto 49 6 100000))
  ([n k r]
   (let [balls (range 1 (inc n))
         random-balls #(take k (shuffle balls))
         empty-counts (zipmap balls (repeat 0))
         append-counts (fn [counts draw]
                         (reduce #(update-in %1 [%2] inc) counts draw))
         counts (reduce append-counts empty-counts (repeatedly r random-balls))]
     (println counts)
     (doseq [[b v] (sort-by val counts)]
       (printf "%d=%.2f%%\n" b (/ (* 100.0 v) r))))))