$polvero = array('a','b','c','d','e','e','e','e','e','f','e','f','e','f','a','a','a','f','f','f');

foreach($polvero as $key=>$value){

if($twice==true and !array_key_exists(1,$twice)){
$string.=$starttag.$value;
}else{
$string.=$endtag.$value;
}

if($polvero[$key-1]==$value && $polvero[$key+1]==$value){
$twice[]=true;
$starttag=’<span>’;
}elseif($twice==true){
$endtag=’</span>’;
if(array_key_exists($key+1,$polvero)){
$twice=false;
}else{
$twice=false;
$end=true;
}
}else{
$endtag=false;
}

}

if($end==true){$string.=’</span>’;}