$_ = "bbbccabcabcabcdba";
    my $l = length;
    s{((\w{$l})\2+)}{($2){@{[length($1)/length($2)]}}}g while -- $l;

##</code><code>##

    (b){3}c(cab){3}cdba

##</code><code>##

    (b){3}c(c(a){2}b){3}cdba