关于概率:转盘-抽奖-概率中奖项计算

//key：奖项key，value：中奖的概率占比或者份数$array = ['key1' => 20, 'key2' => 40, 'key3' => 30, 'key5' => 10];//return：返回中奖的key$fun = function ($array) {    asort($array);//概率大小排序，调配区间，0-10-20-30-40;    $randNum = mt_rand(1, array_sum($array));//随机数    //print_r($randNum . PHP_EOL);    //区间判断    $start = 0;    foreach ($array as $key => $item) {        //结构区间数：0-10-20-30-40;        $start += $item;        //print_r('start:' . $start . ' key:' . $key . PHP_EOL);        if ($randNum <= $start) {            return $key;        }    }};var_dump($fun($array));