8 my @list = map { [$i++, $key * $_] } <>;
11 for my $idx (0 .. $#list) {
13 $i++ while $list[$i][0] != $idx;
14 my $item = splice @list, $i, 1;
15 my $dest = ($item->[1] + $i) % @list;
16 splice @list, $dest, 0, $item;
21 $i++ while $list[$i][1] != 0;