用clojure解决euler problem 9

问题描述：

A Pythagorean triplet is a set of three natural numbers,abc, for which,

a²+b²=c²

For example, 3²+ 4²= 9 + 16 = 25 = 5².

There exists exactly one Pythagorean triplet for whicha+b+c= 1000.
Find the productabc.

解决方案：

(ns euler-problem-9.core)
(defn square
  [n]
  (* n n))

(defn pythagorean-triplet-sum-1000
  []
  (loop [a 1 b 1]
    (if (= (+ (square a) (square b)) (square (- 1000 a b)))
      (* a b (- 1000 a b))
      (if (and (= a 333) (= b 499))
        "no answer"
        (if (= b 499)
          (recur (inc a) 1)
          (recur a (inc b)))))))
(pythagorean-triplet-sum-1000)

(defn pythagorean-triplet-sum-1000-a-b-c
  []
  (loop [a 1 b 1]
    (if (= (+ (square a) (square b)) (square (- 1000 a b)))
      (list a b (- 1000 a b))
      (if (and (= a 333) (= b 499))
        "no answer"
        (if (= b 499)
          (recur (inc a) 1)
          (recur a (inc b)))))))
(pythagorean-triplet-sum-1000-a-b-c)

abc的乘积为：31875000

a，b，c分别为200，375 ，425