Select Code to Download

use strict;
use warnings FATAL => 'all';
...
    printf "Group %d: <%s>\n", $_, substr($string, $-[$_], $+[$_] - $-
+[$_]);
  }
}

Group 0: <aacbbbcac>
Group 1: <ac>
Group 2: <a>
Group 3: <bbb>
Group 4: <c>