3v4l.org

run code in 300+ PHP versions simultaneously
<?php $que = 'bbb ahhj aaab cc iiik xxx fjjj baaaaaab yyyaaa'; echo preg_replace("/\\b([a-z])\\1+(?!\\1|\\b)|(?<=([a-z]))((?!\\2)[a-z])\\3+/","$1$3",$que);

preferences:
30.51 ms | 404 KiB | 5 Q