排序算法出错

Question

我试图将排序方法从Javascript转换为php，我遇到了一些麻烦。

代码如下：

private static function quicksort($ids, $dists, $left, $right) {
    if ($right - $left <= 20) {
        for ($i = $left + 1; $i <= $right; $i++) {
            $temp = $ids[$i];
            $tempDist = $dists[$temp];
            $j = $i - 1;
            while ($j >= $left && $dists[$ids[$j]] > $tempDist) {
                $ids[$j + 1] = $ids[$j--];
            }
            $ids[$j + 1] = $temp;
        }
    } else {
        $median = ($left + $right) >> 1;
        $i = $left + 1;
        $j = $right;
        self::swap($ids, $median, $i);
        if ($dists[$ids[$left]] > $dists[$ids[$right]]) self::swap($ids, $left, $right);
        if ($dists[$ids[$i]] > $dists[$ids[$right]]) self::swap($ids, $i, $right);
        if ($dists[$ids[$left]] > $dists[$ids[$i]]) self::swap($ids, $left, $i);

        $temp = $ids[$i];
        $tempDist = $dists[$temp];
        while (true) {

                do $i++; while ($dists[$ids[$i]] < $tempDist);
                do $j--; while ($dists[$ids[$j]] > $tempDist);

            if ($j < $i) break;
            self::swap($ids, $i, $j);
        }
        $ids[$left + 1] = $ids[$j];
        $ids[$j] = $temp;

        if ($right - $i + 1 >= $j - $left) {
            self::quicksort($ids, $dists, $i, $right);
            self::quicksort($ids, $dists, $left, $j - 1);
        } else {
            self::quicksort($ids, $dists, $left, $j - 1);
            self::quicksort($ids, $dists, $i, $right);
        }
    }
}



private static function swap($arr, $i, $j) {
    $tmp = $arr[$i];
    $arr[$i] = $arr[$j];
    $arr[$j] = $tmp;
}

我使用以下参数运行此代码：

• $ ids-包含80个对象的数组
• $ dists-包含80个对象的数组
• $ left-0
• $ right-79

并在此行显示一条错误，提示未定义偏移：161

                    do $i++; while ($dists[$ids[$i]] < $tempDist);