Sorting algorithms/Bogosort: Difference between revisions

=={{header|Scheme}}==

Uses [[Knuth shuffle]] to shuffle the list.

<lang scheme>(import (rnrs base (6))

(srfi :27 random-bits))

(define (shuffle lst)

(define (swap! vec i j)

(let ((tmp (vector-ref vec i)))

(vector-set! vec i (vector-ref vec j))

(vector-set! vec j tmp)))

(define vec (list->vector lst))

(let loop ((i (sub1 (vector-length vec))))

(unless (zero? i)

(swap! vec i (random-integer (add1 i)))

(loop (sub1 i))))

(vector->list vec))

(define (sorted? lst pred?)

(cond

((null? (cdr lst)) #t)

((pred? (car lst) (cadr lst)) (sorted? (cdr lst) pred?))

(else #f)))

(define (bogosort lst)

(if (sorted? lst <)

lst

(bogosort (shuffle lst))))

(let ((input '(5 4 3 2 1)))

(display "Input: ")

(display input)

(newline)

(display "Output: ")

(display (bogosort input))

(newline))</lang>

{{out}}

<pre>Input: (5 4 3 2 1)

Output: (1 2 3 4 5)</pre>