Data commit

Task/Sorting-Algorithms-Circle-Sort/Racket/sorting-algorithms-circle-sort.rkt

@@ -0,0 +1,35 @@
+#lang racket
+(define (circle-sort v0 [<? <])
+  (define v (vector-copy v0))
+
+  (define (swap-if l r)
+    (define v.l (vector-ref v l))
+    (define v.r (vector-ref v r))
+    (and (<? v.r v.l)
+         (begin (vector-set! v l v.r) (vector-set! v r v.l) #t)))
+
+  (define (inr-cs! L R)
+    (cond
+      [(>= L (- R 1)) #f] ; covers 0 or 1 vectors
+      [else
+       (define M (quotient (+ L R) 2))
+       (define I-moved?
+         (for/or ([l (in-range L M)] [r (in-range (- R 1) L -1)])
+           (swap-if l r)))
+       (define M-moved? (and (odd? (- L R)) (> M 0) (swap-if (- M 1) M)))
+       (define L-moved? (inr-cs! L M))
+       (define R-moved? (inr-cs! M R))
+       (or I-moved? L-moved? R-moved? M-moved?)]))
+
+  (let loop () (when (inr-cs! 0 (vector-length v)) (loop)))
+  v)
+
+(define (sort-random-vector)
+  (define v (build-vector (+ 2 (random 10)) (λ (i) (random 100))))
+  (define v< (circle-sort v <))
+  (define sorted? (apply <= (vector->list v<)))
+  (printf "   ~.a\n-> ~.a [~a]\n\n" v v< sorted?))
+
+(for ([_ 10]) (sort-random-vector))
+
+(circle-sort '#("table" "chair" "cat" "sponge") string<?)