euler009.clj

; Problem 9
; A Pythagorean triplet is a set of three natural numbers, a < b < c,
; for which,
;
; a^2 + b^2 = c^2
; For example, 3^2 + 4^2 = 9 + 16 = 25 = 52.
;
; There exists exactly one Pythagorean triplet for which a + b + c = 1000.
; Find the product abc.

(defn pythagorean? [a b c]
  (= (+ (* a a) (* b b)) (* c c)))

(defn pythagorean-triplets-with-sum [n]
     (for [a (range 1 (- n 3))
	   b (range (inc a) (- n 3))
	   :let [c (- n a b)]
	   :when (pythagorean? a b c)]
       [a b c]))

(def answer
     (reduce * (first (pythagorean-triplets-with-sum 1000))))