use strict;
use warnings;

my $str     = 'xxxx yy zzzzz xxxx qqq xxxx vv zzzzz wwww ppp';
my @lengths = qw/2 4 3/;

my @seqs = getSequences( $str, @lengths );

print "@$_\n" for @seqs;

sub getSequences {
	my ( $string, @lengths )   = @_;
	my ( $i,      @sequences ) = 0;

	my $re = join '\b.+?\b', map { $i++; "(?<C$i>[a-z]{$_})" } @lengths;

	push @sequences, [ map $+{"C$_"}, 1 .. @lengths ]
	  while $string =~ /\b$re\b/ig;

	return @sequences;
}