clojureでqsortその1.clj

(ns org.program.main)

(defn less-vec [v n]
 (cond
  (= 0 (count v)) []
  :else (let [i (first v)]
         (concat (if (< i n) [i] []) (less-vec (rest v) n)))))

(defn greater-vec [v n]
 (cond
  (= 0 (count v)) []
  :else (let [i (first v)]
         (concat (if (>= i n) [i] []) (greater-vec (rest v) n)))))

(defn qsort [v]
 (cond
  (>= 1 (count v)) v
  :else (let [p (first v)
              r (rest v)]
         (concat (qsort (less-vec r p)) [p] (qsort (greater-vec r p))))))

(defn -main [n]
 (qsort n))