Initial data commit

Task/Knuths-algorithm-S/Racket/knuths-algorithm-s.rkt

@@ -0,0 +1,21 @@
+#lang racket/base
+
+(define (s-of-n-creator n)
+  (define i 0)
+  (define sample (make-vector n)) ; the sample of n items
+  (lambda (item)
+    (set! i (add1 i))
+    (cond [(<= i n)               ; we're not full, so kind of boring
+           (vector-set! sample (sub1 i) item)]
+          [(< (random i) n)       ; we've already seen n items; swap one?
+           (vector-set! sample (random n) item)])
+    sample))
+
+(define counts (make-vector 10 0))
+
+(for ([i 100000])
+  (define s-of-n (s-of-n-creator 3))
+  (define sample (for/last ([digit 10]) (s-of-n digit)))
+  (for ([d sample]) (vector-set! counts d (add1 (vector-ref counts d)))))
+
+(for ([d 10]) (printf "~a ~a\n" d (vector-ref counts d)))