generating simple combination in php

Question

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.

Maerlyn, because school branches will be dynamic not static. In the future if we have 5 branches we will add the system 5 branches name so some of our teacher can work 3 branches as a part time teacher... so it should generate the list(array) which I explained already above. in combobox. if i choose "arr1[6]=>xschool atlanta,xschool ortigas,xschool bagio" it means this teacher work in these 3 branches. — Burhan, Oct 16 '14 at 08:19

score 2 · Answer 1 · answered Oct 16 '14 at 04:53

2

I might provide you a direction (pseudocode), this is just one of many ways to solve this. You got to implement your own code ;).

Generate a list of binary number from 000 -> 111 Each number match to 1 permutation.

000 
001 => xschool atlanta
010 => xschool ortigas
100 => xschool bagio
110 => xschool atlanta,xschool ortigas
101 => xschool atlanta,xschool bagio
011 => xschool ortigas,xschool bagio
111 => xschool atlanta,xschool ortigas,xschool bagio

The rest you got to do by yourself. Have fun coding ;)

answered Oct 16 '14 at 04:53

Toby D

1,465
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+1 for the idea, nice... – Ronser Oct 16 '14 at 05:14
2

There will be a soft limit of the number of elements of the input due to the size of integer type. This limitation is quite low (about 31 elements) – Hieu Le Oct 16 '14 at 05:17

score 0 · Accepted Answer · answered Oct 16 '14 at 08:31

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/>";
}

generating simple combination in php

2 Answers2