PHP中如何进行排序算法和搜索算法？

function bubbleSort($arr) {
    $len = count($arr);

    for ($i = 0; $i < $len - 1; $i++) {
        for ($j = 0; $j < $len - $i - 1; $j++) {
            if ($arr[$j] > $arr[$j + 1]) {
                $temp = $arr[$j];
                $arr[$j] = $arr[$j + 1];
                $arr[$j + 1] = $temp;
            }
        }
    }

    return $arr;
}

function quickSort($arr) {
    if (count($arr) < 2) {
        return $arr;
    }

    $pivot = $arr[0];
    $left = $right = [];

    for ($i = 1; $i < count($arr); $i++) {
        if ($arr[$i] < $pivot) {
            $left[] = $arr[$i];
        } else {
            $right[] = $arr[$i];
        }
    }

    return array_merge(quickSort($left), [$pivot], quickSort($right));
}

function mergeSort($arr) {
    if (count($arr) < 2) {
        return $arr;
    }

    $mid = floor(count($arr) / 2);
    $left = array_slice($arr, 0, $mid);
    $right = array_slice($arr, $mid);

    return merge(mergeSort($left), mergeSort($right));
}

function merge($left, $right) {
    $result = [];

    while (count($left) && count($right)) {
        if ($left[0] <= $right[0]) {
            $result[] = array_shift($left);
        } else {
            $result[] = array_shift($right);
        }
    }

    while (count($left)) {
        $result[] = array_shift($left);
    }

    while (count($right)) {
        $result[] = array_shift($right);
    }

    return $result;
}

function linearSearch($arr, $target) {
    $len = count($arr);

    for ($i = 0; $i < $len; $i++) {
        if ($arr[$i] == $target) {
            return $i;
        }
    }

    return -1;
}

function binarySearch($arr, $target) {
    $low = 0;
    $high = count($arr) - 1;

    while ($low <= $high) {
        $mid = floor(($low + $high) / 2);
        if ($arr[$mid] < $target) {
            $low = $mid + 1;
        } else if ($arr[$mid] > $target) {
            $high = $mid - 1;
        } else {
            return $mid;
        }
    }

    return -1;
}