gist:1181618

;; As it turns out, A is much slower than B in some cases, but faster in others! Fun.

(time (sum-divisorsA 2000000)) => "Elapsed time: 3766.863 msecs"
(time (sum-divisorsB 2000000)) => "Elapsed time: 113.786 msecs"

(time (sum-divisorsA 200000))  => "Elapsed time: 3.233 msecs"
(time (sum-divisorsB 200000))  => "Elapsed time: 8.436 msecs"




(time (is-abundant?A 1000000)) => "Elapsed time: 14.259 msecs"
(time (is-abundant?B 1000000)) => "Elapsed time: 58.678 msecs"



;; Methods marked A use the inefficient method, yet produce results faster.
;; Methods marked B use the MUCH faster sum-divisors method with no other changes but gets much slower as the range you sum rises.

(defn is-abundant?A [num]
  (> (sum-divisorsA num) num))

(defn is-abundantB? [num]
  (> (sum-divisorsB num) num))

(defn abundantlistA [start end]
  (filter is-abundant?A (range start end)))

(defn abundantlistB [start end]
  (filter is-abundant?B (range start end)))