PHP简单实现带权重概率抽奖

最新推荐文章于 2024-01-31 16:28:14 发布

Panco95

最新推荐文章于 2024-01-31 16:28:14 发布

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本文介绍了如何使用PHP实现一个基于权重的随机抽奖算法。首先定义了奖品列表及其权重，然后通过打乱数组和计算权重总和进行随机数生成。通过对随机数的处理，找到对应的奖品，从而实现公平的抽奖过程。

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        //奖品列表，weight为权重
        $prizes = [
            ['Index' => 0, 'Weight' => 50],
            ['Index' => 1,'Weight' => 50],
            ['Index' => 2,'Weight' => 40],
            ['Index' => 3,'Weight' => 30],
            ['Index' => 4, 'Weight' => 15],
            ['Index' => 5, 'Weight' => 10],
            ['Index' => 6, 'Weight' => 5],
            ['Index' => 7, 'Weight' => 5],
            ['Index' => 8, 'Weight' => 3],
            ['Index' => 9, 'Weight' => 1],
        ];
        //打乱奖品数组顺序
        shuffle($prizes);
        // 权重计算
        $weightCount = 0;
        foreach ($prizes as $prize) {
            $weightCount += $prize['Weight'];
        }
        // 随机数抽奖，取5次平均值
        $rand1 = mt_rand(1, $weightCount);
        $rand2 = mt_rand(1, $weightCount);
        $rand3 = mt_rand(1, $weightCount);
        $rand4 = mt_rand(1, $weightCount);
        $rand5 = mt_rand(1, $weightCount);
        // 最终随机数
        $rand = intval(($rand1 + $rand2 + $rand3 + $rand4 + $rand5) / 5);
        $lastWeight = 0;   //权重计算中间值
        $userPrize = null; //奖品
        foreach ($prizes as $prize) {
            if ($rand > $lastWeight && $rand <= ($prize['Weight'] + $lastWeight)) {
                $userPrize = $prize;
                break;
            } else {
                $lastWeight += $prize['Weight'];
                continue;
            }
        }

        return $userPrize;