PHP概率，抽奖

随机数，游标卡尺。

一个大饼，随机到哪个坑里，就中哪个奖。

大转盘！

公平公正！

// 获取锦鲤
public function getGoldPig() {
    $pig_gift_bag = [
        [
            'id' => 1,
            'name' => '小金猪',
            'weight' => 1000
        ],
        [
            'id' => 2,
            'name' => '中金猪',
            'weight' => 100
        ],
        [
            'id' => 3,
            'name' => '大金猪',
            'weight' => 10
        ],
        [
            'id' => 4,
            'name' => '超大金猪',
            'weight' => 1
        ],
        [
            'id' => 5,
            'name' => '抱歉，下次就中了',
            'weight' => 10000
        ],
    ];

    foreach ($pig_gift_bag as $key => $val) {
        $giftWeightArr[$val['id']] = $val['weight'];
    }

    for ($i=0;$i<10;$i++) {
        $gid = $this->getLuckyGift($giftWeightArr); //根据概率获取奖项id
        dump($pig_gift_bag[$gid-1]['name']);
    }

}

function getLuckyGift($giftWeightArr) {
    $result = '';

    //概率数组的总概率精度
    $sumWeight = array_sum($giftWeightArr); //计算数组中元素的和
    $luckyNum = mt_rand(1, $sumWeight);
    //概率数组循环
    $beginCursor = $endCursor = 0;
    foreach ($giftWeightArr as $gid => $weight) {
        $beginCursor = $endCursor;
        $endCursor += $weight;

        if ($luckyNum > $beginCursor && $luckyNum <= $endCursor) {
            $result = $gid;
            break;
        }
    }
    return $result;
}

string(24) "抱歉，下次就中了"
string(24) "抱歉，下次就中了"
string(24) "抱歉，下次就中了"
string(24) "抱歉，下次就中了"
string(24) "抱歉，下次就中了"
string(24) "抱歉，下次就中了"
string(24) "抱歉，下次就中了"
string(9) "小金猪"
string(24) "抱歉，下次就中了"
string(9) "小金猪"

有点意思哦！