project euler 71

pe_71.clj

;; Problem 71  : 2011/12/8
;; "Elapsed time: 151.987474 msecs"

(defn my-numerator [n]
  (if (integer? n)
    n
    (numerator (rationalize n))))

(defn my-denominator [n]
  (if (integer? n)
    1
    (denominator (rationalize n))))

(defn frac-reduce [n d]
  (let [frac (/ n d)]
    [(my-numerator frac) (my-denominator frac)]))

(defn pe-71 [base left lmt]
  (let [[base-n base-d] base
	[left-n left-d] left]
    (loop [left-num left-n, left-den left-d]
      (let [[new-num new-den] (frac-reduce (+ base-n left-num) (+ base-d left-den))]
	(if (> new-den lmt)
	  (/ left-num left-den)
	  (recur new-num new-den))))))