langs a-z

Task/Gray-code/Perl-6/gray-code-1.pl6

@@ -0,0 +1,16 @@
+sub gray_encode ( Int $n --> Int ) {
+    return $n +^ ( $n +> 1 );
+}
+
+sub gray_decode ( Int $n is copy --> Int ) {
+    my $mask = 1 +< (32-2);
+    $n +^= $mask +> 1 if $n +& $mask while $mask +>= 1;
+    return $n;
+}
+
+for ^32 -> $n {
+    my $g = gray_encode($n);
+    my $d = gray_decode($g);
+    printf "%2d: %5b => %5b => %5b: %2d\n", $n, $n, $g, $d, $d;
+    die if $d != $n;
+}

Task/Gray-code/Perl-6/gray-code-2.pl6

@@ -0,0 +1,19 @@
+multi bin_to_gray ( [] ) { [] }
+multi bin_to_gray ( [$head, *@tail] ) {
+    return [ $head, ( @tail Z+^ ($head, @tail) ) ];
+}
+
+multi gray_to_bin ( [] ) { [] }
+multi gray_to_bin ( [$head, *@tail] ) {
+    my @bin := $head, (@tail Z+^ @bin);
+    return @bin.flat;
+}
+
+for ^32 -> $n {
+    my @b = $n.fmt('%b').comb;
+    my $g = bin_to_gray(@b);
+    my $d = gray_to_bin($g);
+    printf "%2d: %5s => %5s => %5s: %2d\n",
+            $n, @b.join, $g.join, $d.join, :2($d.join);
+    die if :2($d.join) != $n;
+}