用clojure解決euler problem 3

問題描述：

The prime factors of 13195 are 5, 7, 13 and 29.

What is the largest prime factor of the number 600851475143 ?

(ns euler-problem-3.core)
(defn largest-prime-factor
  [number]
  (loop
      [current-num number,n 2,lpf 2]
    (if (>= lpf current-num)
      lpf
      (if (zero? (rem current-num n))
        (recur (/ current-num n) n n)
        (recur current-num (inc n) lpf)))))
(largest-prime-factor 13195)
(largest-prime-factor 600851475143)

"Elapsed time: 4.15835 msecs"

結果：6857 

right！
遞歸三參數：第一個參數用來保存整除的商，第二個參數用來保存當前的除數，第三個參數用來保存最大的質因素