#! /usr/bin/perl
use strict;
use warnings;

# quickshot: split on "A" if followed by "C"

while ( my $line = <DATA> ) {
        
        my @parts = $line =~ m{(\w*?A)(C\w*?)}g;

        local $, = " ";
        print @parts, "\n";
}

__DATA__
BBACCCCADD
BACBACBACDAC
BACBAC