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@noahlz
Created December 4, 2011 04:47
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(Clojure version) Given an array of integers, determine if any two given elements sum to a given target.
(defn any-pair-make-sum? [arr target]
(let [m (frequencies arr)]
(loop [f (first arr)
x (- target f)
r (rest arr)]
(let [entry (find m x)
only-needs-one-count (not (= x f))]
(if (and entry (or only-needs-one-count (> 1 (val entry))))
true
(if (empty? r)
false
(recur (first r)
(- target (first r))
(rest r))))))))
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