PHP的排列組合有關問題

PHP的排列組合問題
現有數組$arr = array('Area','Income','Age','Gender');
想根據以上數組裡的元素，組成新的數組如下:
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演算法

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------解決方案--------------------

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

