Php 如何使数组组合具有唯一值和有限字符？

我有一个这样的数组 ['1', '2', '3', '4']; 我想让数组的结果像这样

[‘123’、‘124’、‘132’、‘134’、‘142’、‘143’、‘213’、‘214’、‘231’、‘234’、‘241’、‘243’、‘312’、‘314’、‘321’、‘324’、‘341’、‘342’、‘412’、‘413’、‘421’、‘423’、‘431’、‘423’]

这是我的密码

<?php 
ini_set('memory_limit', '-1');

function permute($arg) {
    $array = is_string($arg) ? str_split($arg) : $arg;
    if(1 === count($array))
        return $array;
    $result = array();
    foreach($array as $key => $item)
        foreach(permute(array_diff_key($array, array($key => $item))) as $p)
            $result[] = $item . $p;
    return $result;
}
$array = array('1','2','3','4');
var_dump(permute($array));
 ?>

我想把结果的字符限制为3个字符。怎么做

<?php
function combination($chars, $size, $combinations = array()) {

    if (empty($combinations)) {
        $combinations = $chars;
    }

    # we're done if we're at size 1
    if ($size == 1) {
        return $combinations;
    }
    $new_combinations = array();
    foreach ($combinations as $combination) {
        foreach ($chars as $char) {
            $new_combinations[] = $combination . $char;
        }
    }
    return combination($chars, $size - 1, $new_combinations);

}

function permute($array, $numberOfChar)
{
  $output = combination($array, $numberOfChar);
  $result = array_values(array_filter($output,function($str){
    for($i = 0; $i < strlen($str); $i++) 
    { 
        for($j = $i + 1; $j < strlen($str); $j++)  
        { 
            if($str[$i] == $str[$j]) 
            { 
                return false; 
            } 
        } 
    } 
    return true; 
  }));
  return $result;
}


$array = array(1,2,3,4);
print_r(permute($array, 3)); // pass an array an num of permute char

<?php
function combination($chars, $size, $combinations = array()) {

    if (empty($combinations)) {
        $combinations = $chars;
    }

    # we're done if we're at size 1
    if ($size == 1) {
        return $combinations;
    }
    $new_combinations = array();
    foreach ($combinations as $combination) {
        foreach ($chars as $char) {
            $new_combinations[] = $combination . $char;
        }
    }
    return combination($chars, $size - 1, $new_combinations);

}

function permute($array, $numberOfChar)
{
  $output = combination($array, $numberOfChar);
  $result = array_values(array_filter($output,function($str){
    for($i = 0; $i < strlen($str); $i++) 
    { 
        for($j = $i + 1; $j < strlen($str); $j++)  
        { 
            if($str[$i] == $str[$j]) 
            { 
                return false; 
            } 
        } 
    } 
    return true; 
  }));
  return $result;
}


$array = array(1,2,3,4);
print_r(permute($array, 3)); // pass an array an num of permute char