在php中生成简单组合[重复]

Question

This question already has an answer here:

• Get all permutations of a PHP array? 5 answers

we have 3 school branches:

xschool atlanta 
xschool ortigas
xschool bagio

I will generate a simple combinations.
How can I generate the array which is below in php language

arr1[0]=> xschool atlanta
arr1[1]=>xschool ortigas
arr1[2]=>xschool bagio
arr1[3]=>xschool atlanta,xschool ortigas
arr1[4]=>xschool atlanta,xschool bagio
arr1[5]=>xschool ortigas,xschool bagio
arr1[6]=>xschool atlanta,xschool ortigas,xschool bagio

I wasn't able to set up algorithm in my mind...

Why I need this algorithm? Sometimes our parttime teachers can work in 2 branches different day. So when we add the teacher to our system, the combobox should show us the list(array) which is above.

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Answer 1

Yes, I solved my problem. Here the code:

function combine_set_well($array) {
    // initialize by adding the empty set
    $results = array(array( ));

    foreach ($array as $element)
        foreach ($results as $combination)
            array_push($results, array_merge(array($element), $combination));

    return $results;
}

$set = array('xschool atlanta', 'xschool ortegas', 'xschool bagio');
$ayarla=combine_set_well($set);
asort($ayarla);
foreach ($ayarla as $combination) {
    print join(",", $combination) . "<br/>";
}