php获取数组中相加和最接近或等于(

<code>$count = count($arr);
$array = array();
for($i=0;$i<$count;$i++){
    $r = $arr[$i];
    unset($arr[$i]);
    $sum = abs(array_sum($arr) - $a);
    $array[$sum][] = $arr;
    $arr[] = $r;
}
return $array;</code>

<code>[2] => Array
    (
        [0] => Array
            (
                [1] => 20
                [2] => 10
                [3] => 6
            )

    )

[3] => Array
    (
        [0] => Array
            (
                [3] => 6
                [4] => 15
                [5] => 20
            )

    )

[7] => Array
    (
        [0] => Array
            (
                [2] => 10
                [3] => 6
                [4] => 15
            )

        [1] => Array
            (
                [4] => 15
                [5] => 20
                [6] => 10
            )

    )
</code>

<code>
$maxSize = 38;
$arr = array(15, 20, 10, 6);
$result = array();
$answers = array();
$currSize = 36;
$len = count($arr);
for ($i = 0; $i < $len; $i++) {
    $result[] = array();
    for ($j = 0; $j <= $maxSize; $j++) {
        $result[$i][$j] = 0;
    }
}
for ($i = 0; $i <= $maxSize; $i++) {
    for ($j = 0; $j < $len; $j++) {
        if ($arr[$j] > $i) {
            if ($j === 0) $result[$j][$i] = 0;
            else $result[$j][$i] = $result[$j - 1][$i];
        } else {
            if ($j === 0) $result[$j][$i] = $arr[$j];
            else $result[$j][$i] = max($result[$j - 1][$i], $result[$j - 1][$i - $arr[$j]] + $arr[$j]);
        }
    }
}
// 找出答案
for ($i = $len - 1; $i >= 0 && $currSize !== 0; $i--) {
    if ($result[$i][$currSize] - $result[$i - 1][$currSize - $arr[$i]] === $arr[$i]) {
        $answers[] = $arr[$i];
        $currSize -= $arr[$i];
    }
}
</code>