Project:
 ```1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 ``` ```; two bad sorts (define rand #f) (define randint #f) (let ((two31 #x80000000) (a (make-vector 56 -1)) (fptr #f)) (define (mod-diff x y) (modulo (- x y) two31)) ; generic version ; (define (mod-diff x y) (logand (- x y) #x7FFFFFFF)) ; fast version (define (flip-cycle) (do ((ii 1 (+ ii 1)) (jj 32 (+ jj 1))) ((< 55 jj)) (vector-set! a ii (mod-diff (vector-ref a ii) (vector-ref a jj)))) (do ((ii 25 (+ ii 1)) (jj 1 (+ jj 1))) ((< 55 ii)) (vector-set! a ii (mod-diff (vector-ref a ii) (vector-ref a jj)))) (set! fptr 54) (vector-ref a 55)) (define (init-rand seed) (let* ((seed (mod-diff seed 0)) (prev seed) (next 1)) (vector-set! a 55 prev) (do ((i 21 (modulo (+ i 21) 55))) ((zero? i)) (vector-set! a i next) (set! next (mod-diff prev next)) (set! seed (+ (quotient seed 2) (if (odd? seed) #x40000000 0))) (set! next (mod-diff next seed)) (set! prev (vector-ref a i))) (flip-cycle) (flip-cycle) (flip-cycle) (flip-cycle) (flip-cycle))) (define (next-rand) (if (negative? (vector-ref a fptr)) (flip-cycle) (let ((next (vector-ref a fptr))) (set! fptr (- fptr 1)) next))) (define (unif-rand m) (let ((t (- two31 (modulo two31 m)))) (let loop ((r (next-rand))) (if (<= t r) (loop (next-rand)) (modulo r m))))) (init-rand 19380110) ; happy birthday donald e knuth (set! rand (lambda seed (cond ((null? seed) (/ (next-rand) two31)) ((eq? (car seed) 'get) (cons fptr (vector->list a))) ((eq? (car seed) 'set) (set! fptr (caadr seed)) (set! a (list->vector (cdadr seed)))) (else (/ (init-rand (modulo (numerator (inexact->exact (car seed))) two31)) two31))))) (set! randint (lambda args (cond ((null? (cdr args)) (if (< (car args) two31) (unif-rand (car args)) (floor (* (next-rand) (car args))))) ((< (car args) (cadr args)) (let ((span (- (cadr args) (car args)))) (+ (car args) (if (< span two31) (unif-rand span) (floor (* (next-rand) span)))))) (else (let ((span (- (car args) (cadr args)))) (- (car args) (if (< span two31) (unif-rand span) (floor (* (next-rand) span)))))))))) (define (shuffle x) (do ((v (list->vector x)) (n (length x) (- n 1))) ((zero? n) (vector->list v)) (let* ((r (randint n)) (t (vector-ref v r))) (vector-set! v r (vector-ref v (- n 1))) (vector-set! v (- n 1) t)))) (define (stooge-sort lt? xv . args) (if (null? args) (stooge-sort lt? xv 0 (- (vector-length xv) 1)) (let ((lo (car args)) (hi (cadr args))) (when (lt? (vector-ref xv hi) (vector-ref xv lo)) (let ((t (vector-ref xv lo))) (vector-set! xv lo (vector-ref xv hi)) (vector-set! xv hi t))) (when (< 1 (- hi lo)) (let ((mid (quotient (- hi lo -1) 3))) (stooge-sort lt? xv lo (- hi mid)) (stooge-sort lt? xv (+ lo mid) hi) (stooge-sort lt? xv lo (- hi mid)))))) xv) (define (sorted? lt? xs) (cond ((null? xs) #t) ((null? (cdr xs)) #t) ((lt? (cadr xs) (car xs)) #f) (else (sorted? lt? (cdr xs))))) (define (bogosort lt? xs) (if (sorted? lt? xs) xs (bogosort lt? (shuffle xs)))) (display (stooge-sort < #(1 5 9 8 6 2 4 3 7))) (newline) (display (bogosort < '(1 5 4 2 3))) (newline) ```
 ```1 2 ``` ```#(1 2 3 4 5 6 7 8 9) (1 2 3 4 5) ```