最近做抽奖的活动

1.抽奖算法简化如下：

function choujiang($config)
{
    $isOk = 0;
    foreach ($config['Win'] as $key => $value) {
        if ($value['upperLimit'] > $value['existing']) {
            $isOk = 1;
        }
    }
    if ($isOk === 0) return "所有商品都被中完了";

    $mt_rand = mt_rand(0, 9999); // mt_rand比rand效率要高4倍
    if ($mt_rand < $config['NoWin']['probability']) {
        return '对不起，你没有中奖';
    } else {
        $sum = array_sum(array_column($config['Win'], 'probability'));
        if ($sum !== 10000) return '概率和不等于10000';
        return gailv($config['Win']);
    }
}

function gailv($config)
{
    $mt_rand = mt_rand(0, 9999);
    $begin = 0;
    foreach ($config as $key => $value) {
        if ($mt_rand >= $begin && $mt_rand < $begin + $value['probability']) {
            if ($value['upperLimit'] <= $value['existing']) {
                return gailv($config);
            } else {
                return "恭喜您中奖了，商品id：{$value['product_id']}，商品名：{$value['product_name']}";
            }
        }
        $begin += $value['probability'];
    }
}

/*
    不中奖概率：80.00%
    中奖概率：20.00%，其中：中product1的概率：10.00%, 此种奖品数：500个，已经中了200个
*/

$config = [
    'NoWin' => ['probability' => 8000],
    'Win' => [
        ['product_id' => 1, 'product_name' => 'product1', 'probability' => 1000, 'upperLimit' => 500, 'existing' => 200],
        ['product_id' => 2, 'product_name' => 'product2', 'probability' => 2000, 'upperLimit' => 500, 'existing' => 500],
        ['product_id' => 3, 'product_name' => 'product3', 'probability' => 3000, 'upperLimit' => 500, 'existing' => 200],
        ['product_id' => 4, 'product_name' => 'product4', 'probability' => 4000, 'upperLimit' => 500, 'existing' => 200],
    ]
];

echo choujiang($config);