PHP的排列组合问题
现有数组$arr = array('Area','Income','Age','Gender');
想根据以上数组里的元素，组成新的数组如下:
AreaGenderIncomeAge
AreaGenderAgeIncome
AreaIncomeGenderAge
AreaIncomeAgeGender
AreaAgeGenderIncome
AreaAgeIncomeGender
GenderIncomeAgeArea
GenderIncomeAreaAge
GenderAgeAreaIncome
GenderAgeIncomeArea
GenderAreaAgeIncome
GenderAreaIncomeAge
IncomeAgeGenderArea
IncomeAgeAreaGender
IncomeAreaGenderAge
IncomeAreaAgeGender
IncomeGenderAreaAge
IncomeGenderAgeArea
AgeIncomeAreaGender
AgeIncomeGenderArea
AgeAreaGenderIncome
AgeAreaIncomeGender
AgeGenderAreaIncome
AgeGenderIncomeArea
希望各位大神能提供好的算法
[解决办法]

$arr = array('Area','Income','Age','Gender');
print_r(Arrangement($arr));

//排列 Arrangement
function Arrangement($arr = array(), $res = '') {
  if(! is_array($arr) ) $arr = str_split($arr);
  if(empty($arr)) $array[] = $res;
  else foreach($arr AS $k => $v) {
    unset($arr[$k]);
    foreach( Arrangement($arr, $res . " $v") AS $t) $array[] = $t;
    $arr[$k]    = $v;
  }
  return  $array;
}

Array
(
[0] => Area Income Age Gender
[1] => Area Income Gender Age
[2] => Area Age Gender Income
[3] => Area Age Income Gender
[4] => Area Gender Income Age
[5] => Area Gender Age Income
[6] => Income Age Gender Area
[7] => Income Age Area Gender
[8] => Income Gender Area Age

[9] => Income Gender Age Area
[10] => Income Area Age Gender
[11] => Income Area Gender Age
[12] => Age Gender Area Income
[13] => Age Gender Income Area
[14] => Age Area Income Gender
[15] => Age Area Gender Income
[16] => Age Income Gender Area
[17] => Age Income Area Gender
[18] => Gender Area Income Age
[19] => Gender Area Age Income
[20] => Gender Income Age Area
[21] => Gender Income Area Age
[22] => Gender Age Area Income
[23] => Gender Age Income Area
)