Question

I’ve two arrays like this:

$arr = Array (1, 2, 3 ,4 ,5, 6 ,7 ,8 ) ;

and this:

$arr2 = Array (7, 6, 5,8 ,3 ,2 ,1, 4 )  

The pairs of these arrays are the numbers with the same key ($arr[0]-$arr2[0] ecc.)

1-7
2-6
3-5
4-8
5-3
6-2
7-1
8-4

as you can see there are some duplicate pairs like 1-7 and 7-1 , 2-6 and 6-2 , 3-5 and 5-3, 4-8 and 8-4.

I need a function who recives these two arrays and return one array with each single pairs.

For example this is what the function should returns:

Array ( [0] => 1 [1] => 7 [2] => 2 [3] => 6 [4] => 3 [5] => 5 [6] => 4 [7] => 8 ) 

As you can see the pairs ares: 1-7 , 2-6, 3-5 and 4-8.

I’ve made this function who doesnt work properly:

function free_pairs($arr,$arr2){
$ok = 0;
$ris = array();
$indice_ris=0;
for ($i=1; $i <=count($arr) ; $i++) { 
    $x1 = $arr[$i];
    $x2 = $arr2[$i];
    for ($j=1; $j <= count($arr2) ; $j++) { 
        $y1 = $arr[$j];
        $y2 = $arr2[$j];
        if($x1 != $y2 && $x2 != $y1){
            $ok = 1;
        } else {
            $ok = 0;
        }
    }
    if ($ok == 1) {
        $ris[$indice_ris] = $x1;
        $ris[$indice_ris+1] = $x2;
        $indice_ris = $indice_ris+2;
        $ok = 0;
    }
    return $ris;
}

I think the problem is in this if:

if($x1 != $y2 && $x2 !=$y1)

What do you think about?

Answer 1

After some corrections on your original script, this seems to work:

$arr1 = Array (1, 2, 3, 4 ,5, 6 ,7 ,8);
$arr2 = Array (7, 6, 5, 8 ,3 ,2 ,1, 4);
$res = free_pairs($arr1, $arr2);
print_r($res);

function free_pairs($arr,$arr2){
    $ris = array();
    for ($i = 0; $i < count($arr); $i++) { 
        $x1 = $arr[$i];
        $x2 = $arr2[$i];
        $ok = 0;
        for ($j = $i+1; $j < count($arr2); $j++) { 
            $y1 = $arr[$j];
            $y2 = $arr2[$j];
            if($x1 == $y2 && $x2 == $y1){
                $ok = 1;
            }
        }
        if ($ok == 0) {
            $ris[] = $x1;
            $ris[] = $x2;
        }
    }
    return $ris;
}

output:

Array
(
    [0] => 5
    [1] => 3
    [2] => 6
    [3] => 2
    [4] => 7
    [5] => 1
    [6] => 8
    [7] => 4
)