draft

<?php

$n = 83;
$arr1 = [34,52,11,23,73,21,52,35,26,5,7,6,12,11,2];
print_r($arr1);
rsort($arr1);

$result = array();
$done = 0;
$dummy_arr = $arr1; // container of imaginary array to be compared
$dummy_n = $n; // initialize the amount needed
foreach ($arr1 as $key => $a) {
    if ($dummy_n < $a){
        continue;
    }elseif($dummy_n == $a){
        $result[] = $a;
    }else{
        $result[] = $a;
        $dummy_n = $dummy_n - $a;
    }
    $total = array_sum($result);
    if ($total == $n){
        $done = 1;
        break;
    }
}
echo "<br><hr>";
echo "result<br>";
print_r($result);