php计算24点游戏

求: 三个5,一个1组成的数学表达式的结果=24, 结果:(5-1/5)*5=24

set_time_limit(0);
$values = array(1, 5, 5, 5);
$result = 24;

$list = array();

echo "

";
 makeValue($values);
 print_r($list);
 function makeValue($values, $set=array())
 {
  $words = array("+", "-", "*", "/");
  if(sizeof($values)==1)
  {
   $set[] = array_shift($values);
   return makeSpecial($set);
  }
  foreach($values as $key=>$value)
  {
   $tmpValues = $values;
   unset($tmpValues[$key]);
   foreach($words as $word)
   {
    makeValue($tmpValues, array_merge($set, array($value, $word)));
   }
  }
 } 

 function makeSpecial($set)
 {
  $size = sizeof($set);
  if($size  {
   return makeResult($set);
  }
  for($len=3; $len  {
   for($start=0; $start   {
    if(!($set[$start-1]=="*" || $set[$start-1]=="/" || $set[$start+$len]=="*" || $set[$start+$len]=="/"))
     continue;
    $subSet = array_slice($set, $start, $len);
    if(!in_array("+", $subSet) && !in_array("-", $subSet))
     continue;
    $tmpSet = $set;
    array_splice($tmpSet, $start, $len-1);
    $tmpSet[$start] = "(".implode("", $subSet).")";
    makeSpecial($tmpSet); 
   }
  }
 } 

 function makeResult($set)
 {
  global $result, $list;
     $str = implode("", $set);
  @eval("\$num=$str;");
  if($num==$result && !in_array($str, $list))
   $list[] = $str;
 } 
?>