Initial data commit

Task/Superpermutation-minimisation/Racket/superpermutation-minimisation.rkt

@@ -0,0 +1,33 @@
+#lang racket/base
+(require racket/list racket/format)
+
+(define (index-of1 x l) (for/first ((i (in-naturals 1)) (m (in-list l)) #:when (equal? m x)) i))
+
+(define (sprprm n)
+  (define n-1 (- n 1))
+  (define sp:n-1 (superperm n-1))
+  (let loop ((subs (let loop ((sp sp:n-1) (i (- (length sp:n-1) n-1 -1)) (rv null))
+                     (cond
+                       [(zero? i) (reverse rv)]
+                       [else
+                        (define sub (take sp n-1))
+                        (loop (cdr sp)
+                              (- i 1)
+                              (if (check-duplicates sub) rv (cons sub rv)))])))
+             (ary null))
+    (if (null? subs)
+        ary
+        (let ((sub (car subs)))
+          (define i (if (null? ary) 0 (index-of1 (last ary) sub)))
+          (loop (cdr subs) (append ary (drop sub i) (list n) sub))))))
+
+(define superperm
+  (let ((hsh (make-hash (list (cons 1 (list 1))))))
+    (lambda (n) (hash-ref! hsh n (lambda () (sprprm n))))))
+
+
+(define (20..20 ary)
+  (if (< (length ary) 41) ary (append (take ary 20) (cons '.. (take-right ary 20)))))
+
+(for* ((n (in-range 1 (add1 8))) (ary (in-value (superperm n))))
+  (printf "~a: len = ~a : ~a~%" (~a n #:width 3) (~a (length ary) #:width 8) (20..20 ary)))