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March 2014 update

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Ingy döt Net 2014-04-02 16:56:35 +00:00
parent 09687c4926
commit a25938f123
1846 changed files with 21876 additions and 5203 deletions
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20
Task/Knuths-algorithm-S/Racket/knuths-algorithm-s.rkt
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@ -1,29 +1,29 @@
#lang racket
#lang racket/base
(define (s-of-n-creator n)
(let* ([count 0] ; 'i' in the description
(let ([count 0] ; 'i' in the description
[vec (make-vector n)]) ; store the elts we've seen so far
(lambda (item)
(if (< count n)
; we're not full, so, kind of boring
(begin
(vector-set! vec count item)
(set! count (+ count 1))
(vector-copy vec 0 count))
(set! count (+ count 1)))
; we've already seen n elts; fun starts
(begin
(set! count (+ count 1))
(when (< (random) (/ n count))
(vector-set! vec (random n) item))
(vector-copy vec))))))
(when (< (random count) n)
(vector-set! vec (random n) item))))
vec)))
(define counts (make-vector 10))
(define counts (make-hash '((0 . 0) (1 . 0) (2 . 0) (3 . 0) (4 . 0) (5 . 0) (6 . 0) (7 . 0) (8 . 0) (9 . 0))))
(for ([iter (in-range 0 100000)]) ; trials
(let ([s-of-n (s-of-n-creator 3)]) ; set up the chooser
(for ([d (in-vector ; iterate over the chosen digits
(for/last ([digit (in-range 0 10)]) ; loop through the digits
(s-of-n digit)))]) ; feed them in
(hash-update! counts d add1)))) ; update counts
(vector-set! counts d (add1 (vector-ref counts d)))))) ; update counts
(for ([d (in-range 0 10)])
(printf "~a ~a~n" d (hash-ref counts d)))
(printf "~a ~a~n" d (vector-ref counts d)))