示例解析php的大转盘概率算法

// 奖品列表
$Goods_list = array(
    array('id'=>1,'name'=>'特等奖','num'=>1,'rate'=>0.01),
    array('id'=>2,'name'=>'一等奖','num'=>10,'rate'=>0.1),
    array('id'=>3,'name'=>'二等奖','num'=>20,'rate'=>0.2),
    array('id'=>4,'name'=>'三等奖','num'=>50,'rate'=>0.49),
    array('id'=>5,'name'=>'感谢参与','num'=>1000,'rate'=>0.2),
);

// 计算总概率
$total_rate = 0;
foreach ($goods_list as $goods) {
    $total_rate += $goods['rate'];
}

// 随机概率
$rand_rate = mt_rand() / mt_getrandmax() * $total_rate;

// 计算中奖的奖品
$win_goods = null;
foreach ($goods_list as $goods) {
    if ($rand_rate <= $goods['rate']) {
        $win_goods = $goods;
        break;
    }
    $rand_rate -= $goods['rate'];
}

// 如果有中奖奖品，减少奖品数量
if ($win_goods) {
    $win_goods['num']--;
}