$gailv_arr = array();

        $gailv_arr[11] = 1;

        $gailv_arr[2] = 1;

        $gailv_arr[33] = 1;

        $gailv_arr[44] = 1;

        $gailv_arr[55] = 1;

        $proSum = array_sum($gailv_arr);

if($proSum==0){

echo "没有奖品了";

exit();

}

        arsort($gailv_arr);

        //概率数组循环

        $zhongjiang_id = 0;

        foreach ($gailv_arr as $key => $vo) {

            $randNum = mt_rand(1, $proSum);

            if ($randNum <= $vo) {

                $zhongjiang_id = $key;

                break;

            } else {

                $proSum -= $vo;

            }

        }

        echo $zhongjiang_id;