Data commit

Task/Knuth-shuffle/Racket/knuth-shuffle.rkt

@@ -0,0 +1,16 @@
+#lang racket
+
+(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 (knuth-shuffle x)
+  (if (list? x)
+    (vector->list (knuth-shuffle (list->vector x)))
+    (begin (for ([i (in-range (sub1 (vector-length x)) 0 -1)])
+             (define r (random (+ i 1)))
+             (swap! x i r))
+           x)))
+
+(knuth-shuffle '(1 2 3 4))