#!/usr/bin/perl -w
use strict;

while (<DATA>) {
    chomp;
    $_ =~ s/(\w)(\1+)/\($1$2\)/g;
    print "$_\n";
}

__DATA__
thhheeee good boyy
the qqquick brrrowwwn fooox

##</code><code>##

t(hhh)(eeee) g(oo)d bo(yy)
the (qqq)uick b(rrr)o(www)n f(ooo)x