PHP 中两个数组的完全唯一组合

Question

I've been struggling with this question for an entire work day I cannot craft a viable solution that doesn't either take huge amounts of memory or take forever to complete.

If I have two arrays:

$letters = array ('a','b','c','d');

$numbers = array (1,2,3,4);

How do I get COMPLETELY unique combinations? In other words, since these arrays have four elements each, the function should return four combinations ONLY, with each element in the arrays only used once.

Example combinations using the arrays above:

a1 b2 c3 d4

-or-

a2 b4 c3 d1

-or-

a4 b2 c3 d1

...etc...

All of the examples I find do not take uniqueness of both arrays into account. Answers like this are not valid:

a1 b2 c3 d3

-or-

a3 b2 c3 d2

I'm having a hell of a time crafting a function that works properly.

Answer 1

Given the arrays are both of equal length as in your example, maybe something like this, using shuffle :

<?php

$letters = array ('a','b','c','d');
$numbers = array (1,2,3,4);

function randmix($a, $b){
    shuffle($a);
    shuffle($b);
    foreach($a as $i => $val){
        $product []= $val.$b[$i];
    }
    return $product;
}

print_r(randmix($letters,$numbers));

 Array ( [0] => d1 [1] => a3 [2] => c4 [3] => b2 )

Answer 2

Another possibility without shuffling the arrays beforehand (not that there's anything wrong with that; just a different approach):

while ($letters && $numbers) {              // keep going as long as both arrays have values
    $combination = '';
    foreach ([&$letters, &$numbers] as &$array) {

        // select a random element from each array and then unset it
        $key = array_rand($array);
        $combination .= $array[$key];
        unset($array[$key]);
    }
    $combinations[] = $combination;
}