Initial data commit

Task/Verhoeff-algorithm/Raku/verhoeff-algorithm.raku

@@ -0,0 +1,47 @@
+my @d = [^10] xx 5;
+@d[$_][^5].=rotate($_), @d[$_][5..*].=rotate($_) for 1..4;
+push @d: [@d[$_].reverse] for flat 1..4, 0;
+
+my @i = 0,4,3,2,1,5,6,7,8,9;
+
+my %h = flat (0,1,5,8,9,4,2,7,0).rotor(2 =>-1).map({.[0]=>.[1]}), 6=>3, 3=>6;
+my @p = [^10],;
+@p.push: [@p[*-1].map: {%h{$_}}] for ^7;
+
+sub checksum (Int $int where * ≥ 0, :$verbose = True ) {
+    my @digits = $int.comb;
+    say "\nCheckdigit calculation for $int:";
+    say " i  ni  p(i, ni)  c" if $verbose;
+    my ($i, $p, $c) = 0 xx 3;
+    say " $i   0      $p     $c" if $verbose;
+    for @digits.reverse {
+        ++$i;
+        $p = @p[$i % 8][$_];
+        $c = @d[$c; $p];
+        say "{$i.fmt('%2d')}   $_      $p     $c" if $verbose;
+    }
+    say "Checkdigit: {@i[$c]}";
+    +($int ~ @i[$c]);
+}
+
+sub validate (Int $int where * ≥ 0, :$verbose = True) {
+    my @digits = $int.comb;
+    say "\nValidation calculation for $int:";
+    say " i  ni  p(i, ni)  c" if $verbose;
+    my ($i, $p, $c) = 0 xx 3;
+    for @digits.reverse {
+        $p = @p[$i % 8][$_];
+        $c = @d[$c; $p];
+        say "{$i.fmt('%2d')}   $_      $p     $c" if $verbose;
+        ++$i;
+    }
+    say "Checkdigit: {'in' if $c}correct";
+}
+
+## TESTING
+
+for 236, 12345, 123456789012 -> $int {
+    my $check = checksum $int, :verbose( $int.chars < 8 );
+    validate $check, :verbose( $int.chars < 8 );
+    validate +($check.chop ~ 9), :verbose( $int.chars < 8 );
+}