update

Task/Sorting-algorithms-Shell-sort/Racket/sorting-algorithms-shell-sort.rkt

@@ -0,0 +1,14 @@
+#lang racket
+(define (shell-sort! xs)
+  (define (ref i) (vector-ref xs i))
+  (define (new Δ) (if (= Δ 2) 1 (exact-floor (/ (* Δ 5) 11))))
+  (let loop ([Δ (quotient (vector-length xs) 2)])
+    (unless (= Δ 0)
+      (for ([xi (in-vector xs)] [i (in-naturals)])
+        (let while ([i i])
+          (cond [(and (>= i Δ) (> (ref (- i Δ)) xi))
+                 (vector-set! xs i (ref (- i Δ)))
+                 (while (- i Δ))]
+                [(vector-set! xs i xi)])))
+      (loop (new Δ))))
+  xs)