X-Git-Url: https://git.gag.com/?p=debian%2Fgnuradio;a=blobdiff_plain;f=gnuradio-core%2Fsrc%2Futils%2Fpermute.scm;fp=gnuradio-core%2Fsrc%2Futils%2Fpermute.scm;h=23ddfc9991876aed51c324e6d353fdfda201d6f1;hp=0000000000000000000000000000000000000000;hb=8a9ddbb0675f9bfcc6e03b457fba6c79474a3693;hpb=82d471b9b4a8b389b5da44b19c69c36420828382

diff --git a/gnuradio-core/src/utils/permute.scm b/gnuradio-core/src/utils/permute.scm
new file mode 100644
index 00000000..23ddfc99
--- /dev/null
+++ b/gnuradio-core/src/utils/permute.scm
@@ -0,0 +1,27 @@
+(require 'common-list-functions)
+
+
+(define (permute lst)
+  (define (aux set head)
+    (cond ((null? set) head)
+	  (else
+	   (map (lambda (x)
+		  (aux (set-difference set (list x))
+		       (cons x head)))
+		set))))
+  (aux lst '()))
+
+(define (permute-2 lst)
+  (let ((result '()))
+    (define (aux set head)
+      (if (null? set)
+	  (set! result (cons head result))
+	  (for-each (lambda (x)
+		      (aux (set-difference set (list x))
+			   (cons x head)))
+		    set)))
+    (aux lst '())
+    result))
+
+
+