/**
* @en Generating all permutations of a given array
* @ru Получение всех возможны вариантов перестановок элементов массива
*
* $array = array('AAA', 'BBB', 'CCC');
*
* $result = arrays::permutation($array); # Array
* # (
* # [0] => Array
* # (
* # [0] => AAA
* # [1] => BBB
* # [2] => CCC
* # )
* #
* # [1] => Array
* # (
* # [0] => AAA
* # [1] => CCC
* # [2] => BBB
* # )
* #
* # [2] => Array
* # (
* # [0] => BBB
* # [1] => CCC
* # [2] => AAA
* # )
* #
* # [3] => Array
* # (
* # [0] => BBB
* # [1] => AAA
* # [2] => CCC
* # )
* #
* # [4] => Array
* # (
* # [0] => CCC
* # [1] => AAA
* # [2] => BBB
* # )
* #
* # [5] => Array
* # (
* # [0] => CCC
* # [1] => BBB
* # [2] => AAA
* # )
* # )
*
* @param array $array
*
* @return array
*/
public static function permutation($array)
{
$results = array();
if (count($array) == 1) {
$results[] = $array;
} else {
for ($i = 0; $i < count($array); $i++) {
$first = array_shift($array);
$subresults = items::permutation($array);
array_push($array, $first);
foreach ($subresults as $subresult) {
$results[] = array_merge(array($first), $subresult);
}
}
}
return $results;
}
/**
* @en Generating all permutations of a given string
* @ru Строковая комбинаторика. Получение всех возможны вариантов перестановок элементов строки
*
*
* $result = string::permutation('AAA BBB CCC DDD'); # Array
* # (
* # [0] => AAA BBB CCC DDD
* # [1] => AAA BBB DDD CCC
* # [2] => AAA CCC DDD BBB
* # [3] => AAA CCC BBB DDD
* # [4] => AAA DDD BBB CCC
* # [5] => AAA DDD CCC BBB
* # [6] => BBB CCC DDD AAA
* # [7] => BBB CCC AAA DDD
* # [8] => BBB DDD AAA CCC
* # [9] => BBB DDD CCC AAA
* # [10] => BBB AAA CCC DDD
* # [11] => BBB AAA DDD CCC
* # [12] => CCC DDD AAA BBB
* # [13] => CCC DDD BBB AAA
* # [14] => CCC AAA BBB DDD
* # [15] => CCC AAA DDD BBB
* # [16] => CCC BBB DDD AAA
* # [17] => CCC BBB AAA DDD
* # [18] => DDD AAA BBB CCC
* # [19] => DDD AAA CCC BBB
* # [20] => DDD BBB CCC AAA
* # [21] => DDD BBB AAA CCC
* # [22] => DDD CCC AAA BBB
* # [23] => DDD CCC BBB AAA
* # )
*
*
* @param string $string Any string
* @param string $delimiter
*
* @return array
*/
public static function permutation($string, $delimiter = ' ')
{
$array = items::permutation(explode($delimiter, $string));
$result = null;
foreach ($array as $item) {
$result[] = implode(' ', $item);
}
return $result;
}