CODEWITHSUNDEEP
phparraysalgorithm
Enthys
Enthys

Reputation: 305

Get all possible combinations without duplicates

How can I get all the possible combinations of given numbers. For instance I have

$arr = [ 1, 2, 3, 4]

I want to get the combinations without any duplicates inside the combinations

[1] => [1]
[2] => [2]
[3] => [3]
[4] => [4]
[5] => [1, 2]
[6] => [1, 3]
[7] => [1, 4]
[8] => [2, 3]
[9] => [2, 4]
[10] => [3, 4]
[11] => [1, 2, 3]
[12] => [1, 2, 4]
[13] => [1, 3, 4]
[14] => [2, 3, 4]
[15] => [1, 2, 3, 4]

Upvotes: 3

Views: 2171

Answers (2)

Chika
Chika

Reputation: 25

I didn't like that the given solution is modifying an iterated variable within its loop and also I wanted a solution that I can easily understand to port to other languages. So here:

<?php
function permutation(array $arr)
{
        $out=[[]];
    
        foreach($arr as $key2=> $item2){
            $copy=$out;
            foreach($copy as $k=> $v){
                array_push($copy[$k],$item2 );
            }
            array_push($out,...$copy);
            
        }
        
        return $out;
}
print_r(permutation(array(1,2,3,4)));

This second one is intentionally weird to make it better to understand what is going on.

<?php
function permutation(array $arr)
{
    
    $out=[];
    
    while(count($arr)){
        
        $out_temp=[[]];
    
        foreach($arr as $key2=> $item2){
            $copy=$out_temp;
            foreach($copy as $k=> $v){
                array_push($copy[$k],$item2 );
            }
            if($key2==0){
                unset($out_temp[0]);
            }
            array_push($out_temp,...$copy);
 
        }
        
        array_push($out,...$out_temp);
        array_shift($arr);
    }

    return $out;
}
print_r(permutation(array(1,2,3,4,5)));

Upvotes: 0

Hardik Solanki
Hardik Solanki

Reputation: 3195

I hope below function work as per your expected output : 

function get_array_combination($arr) {
    $results = array(array( ));

    foreach ($arr as $values)
        foreach ($results as $combination)
                array_push($results, array_merge($combination, array($values))); // Get new values and merge to your previous combination. And push it to your results array
    return $results;
}
$set = array('1', '2', '3', '4');
$final_array = get_array_combination($set);
echo "<pre>";
print_r(array_values(array_filter($final_array))); // Removed blank entry from array and re indexing array keys.

Upvotes: 4

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