coins.clj

(ns coins)

(def heads (repeat 50 :H))
(def tails (repeat 50 :T))

(def flip {:H :T :T :H})

(defn permutation [n]
  [(concat (take n heads) (drop n tails))
   (concat (drop n heads) (take n tails))])

(defn count-coins
  [face coins]
  (count (filter #{face} coins)))

(if (every? true? (map (fn [n]
       (let [[left right] (permutation n)]
         (= (count-coins :T (map flip left))
            (count-coins :T right))))
     (range 51)))
  (println "Looks like it works for all combinations!")
  (println "Looks like you win, sir wobin...."))