Sorting algorithms/Heapsort: Difference between revisions

=={{header|Clojure}}==

{{trans|OCaml}}

<lang lisp>

(defn- swap [a i j]

(assoc a i (nth a j) j (nth a i)))

(defn- sift [a pred k l]

(loop [a a x k y (inc (* 2 k))]

(if (< (inc (* 2 x)) l)

(let [ch (if (and (< y (dec l)) (pred (nth a y) (nth a (inc y))))

(inc y)

y)]

(if (pred (nth a x) (nth a ch))

(recur (swap a x ch) ch (inc (* 2 ch)))

a))

a)))

(defn heapsort

([a pred]

(let [len (count a)]

(reduce (fn [c term] (sift (swap c term 0) pred 0 term))

(reduce (fn [c i] (sift c pred i len))

(vec a)

(range (dec (int (/ len 2))) -1 -1))

(range (dec len) 0 -1))))

([a]

(heapsort a <)))

</lang>

Example usage:

<lang lisp>

user> (heapsort [1 2 4 6 2 3 6])

[1 2 2 3 4 6 6]

user> (heapsort [1 2 4 6 2 3 6] >)

[6 6 4 3 2 2 1]

user> (heapsort (list 1 2 4 6 2 3 6))

[1 2 2 3 4 6 6]

</lang>