Code and Coffee - 12/5/2012

change_for.clj

defn change-for [change coins returning]
  (let [ coin (first coins)
         others (rest coins)
        ]
	(cond
        (= change 0) returning
    	(>= change coin) (change-for (mod change coin) others (conj returning {coin (int (/ change coin))}))
     	:else (change-for change others returning))))

(defn make-change [price tendered]
  (let [ change (- tendered price) ]
    (change-for change [25 10 5 1] {})))




(= (make-change 125 200) {25 3})
(make-change 124 200)
(= (make-change 124 200) {25 3, 1 1})
(make-change 126 200)
(= (make-change 126 200) {25 2, 10 2, 1 4})