Subarray for the given sum

subCountItems.php

<?php

/*
 * Find a subarray with the minimum number of items
 * which sum is equal to the requested sum.
 *
 * Items [1, 2, 3, 5] and sum of 5 will return [5]
 * Items [1, 2, 3, 5] and sum of 4 will return [1, 3]
 * Items [1, 2, 3, 5] and sum of 8 will return [3, 5]
 * Items [1, 2, 3, 5] and sum of 9 will return [1, 3, 5]
 * Items [1, 2, 3, 5] and sum of 12 will return []
 */
function getSubCountItems($candidates, $sum, $items=[[]])
{
    $newItems = [];
    $count = count($candidates);

    foreach ($items as $item) {
        end($item);
        $start = key($item) !== null ? key($item) + 1: 0;

        for ($i = $start; $i < $count; $i++) {
            $add = $item + [$i => $candidates[$i]];
            $checkSum = array_sum($add);

            if ($checkSum == $sum) {
                return $add;
            }
            $newItems[] = $add;
        }
    }

    if (!empty($newItems)) {
        return getSubCountItems($candidates, $sum, $newItems);
    }
    return $newItems;
}