根据比例计算随机中奖

                //算法修改 @ln
                if($media_app['MediaApp']['ratio']){
                    $max_rand_number = 1 / $media_app['MediaApp']['ratio'];
                    $rand_value       = rand( 1, $max_rand_number );
                    $is_become_winner = ( $rand_value == 1 );
                }