RosettaCodeData/Task/Modular-inverse/Perl/modular-inverse-2.pl

16 lines
364 B
Raku

sub invmod {
my($a,$n) = @_;
my($t,$nt,$r,$nr) = (0, 1, $n, $a % $n);
while ($nr != 0) {
# Use this instead of int($r/$nr) to get exact unsigned integer answers
my $quot = int( ($r - ($r % $nr)) / $nr );
($nt,$t) = ($t-$quot*$nt,$nt);
($nr,$r) = ($r-$quot*$nr,$nr);
}
return if $r > 1;
$t += $n if $t < 0;
$t;
}
say invmod(42,2017);