How to Generate All Combinations from a 1D Array in PHP Using a Recursive Depth-First Search?

Getting All Combinations of a 1D Array

The task of assembling all attainable combinations from a one-dimensional array can be achieved by utilizing a recursive method. This approach encompasses a depth-first search approach, exploring every possible combination while maintaining the integrity of each element's arrangement.

Consider the following PHP code, which effectively handles the aforementioned task:

<code class="php"><?php

$array = array('Alpha', 'Beta', 'Gamma', 'Sigma');

function depth_picker($arr, $temp_string, &$collect) {
    if ($temp_string != "") 
        $collect []= $temp_string;

    for ($i=0, $iMax = sizeof($arr); $i < $iMax; $i++) {
        $arrcopy = $arr;
        $elem = array_splice($arrcopy, $i, 1); // removes and returns the i'th element
        if (sizeof($arrcopy) > 0) {
            depth_picker($arrcopy, $temp_string ." " . $elem[0], $collect);
        } else {
            $collect []= $temp_string. " " . $elem[0];
        }   
    }   
}

$collect = array();
depth_picker($array, "", $collect);
print_r($collect);

?></code>

This implementation operates by traversing the input array recursively, analyzing each element and its potential impact on the overall combination set. When an element is included in the combination, a new array without that element is created for further exploration. This process continues until all elements are examined and the full spectrum of combinations is captured.

By employing this approach, you can successfully retrieve every possible combination from the provided 1D array, satisfying the requirements of retaining both the original sequence and featuring distinct arrangements.

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