穷举排列组合的函数

<?php
function getSequenceAry($arr)
{
    if (count($arr) == 1) {
        return array($arr);
    }
    $arrRet = array();
    foreach ($arr as $k => $v) {
        $arr2 = $arr;
        unset($arr2[$k]);
        $arrOrderList = getSequenceAry($arr2);
        foreach ($arrOrderList as $order) {
            array_unshift($order, $v);
            $arrRet[] = $order;
        }
    }
    return $arrRet;
}

function getSequenceStr($arr)
{
    if (count($arr) == 1) {
        return $arr;
    }
    $arrRet = array();
    foreach ($arr as $k => $v) {
        $arr2 = $arr;
        unset($arr2[$k]);
        $arrOrderList = getSequenceStr($arr2);
        foreach ($arrOrderList as $order) {
            $arrRet[] = $v . $order;
        }
    }
    return $arrRet;
}


print_r(getSequenceAry(array(1,2,3)));
print_r(getSequenceStr(array(1,2,3)));
------------------ output ------------------
Array
(
    [0] => Array
        (
            [0] => 1
            [1] => 2
            [2] => 3
        )

    [1] => Array
        (
            [0] => 1
            [1] => 3
            [2] => 2
        )

    [2] => Array
        (
            [0] => 2
            [1] => 1
            [2] => 3
        )

    [3] => Array
        (
            [0] => 2
            [1] => 3
            [2] => 1
        )

    [4] => Array
        (
            [0] => 3
            [1] => 1
            [2] => 2
        )

    [5] => Array
        (
            [0] => 3
            [1] => 2
            [2] => 1
        )

)
Array
(
    [0] => 123
    [1] => 132
    [2] => 213
    [3] => 231
    [4] => 312
    [5] => 321
)