sub gcd { $_[1] ? gcd($_[1], $_[0] % $_[1]) : $_[0] } sub shuffle { my ($seed, $max, $i) = @_; my $ca = $seed; $ca-- until gcd($ca, $max) == 1; my $cb = $seed - $ca; ($ca * $i + $cb) % $max; } for my $seed (1 .. 10) { my @result = map shuffle($seed, 15, $_), 0 .. 14; print "seed=$seed ==> @result\n"; }