还在抱怨王者荣耀水晶难抽？PHP一文带你搞懂游戏中的抽奖算法

一、初始化奖品

• id 奖品的id
• pid 奖品的自定义id
• type 奖品类型，1、虚拟奖品 2、实物奖品 3、礼包码 待扩充
• name 奖品名称
• total 奖品总数
• chance 获奖概率/抽奖基数10000
• daynum 每日数量限制
• pay 充值限制

  1 <?php
  2 $prize = [
  3     ['id' => 1, 'pid' => 11, 'type' => 1, 'name' => '典藏英雄', 'total' => 20, 'chance' => 1000, 'daynum' => 10, 'pay' => 2000 ],
  4     ['id' => 2, 'pid' => 12, 'type' => 1, 'name' => '史诗皮肤', 'total' => 40, 'chance' => 1000, 'daynum' => 10, 'pay' => 4000 ],
  5     ['id' => 3, 'pid' => 13, 'type' => 1, 'name' => '钻石奖励', 'total' => 80, 'chance' => 1000, 'daynum' => 10, 'pay' => 4000 ],
  6     ['id' => 4, 'pid' => 14, 'type' => 1, 'name' => '荣耀水晶', 'total' => 20, 'chance' => 1000, 'daynum' => 10, 'pay' => 8000 ]
  7 ];

  •  奖品详情应该从数据库中读出来
  • 奖品详情应该加入缓存，避免数据库的压力

  二、谢谢参与

  1 <?php
  2 $thanks_prize = [
  3     'id' => 0,
  4     'pid' => 0,
  5     'type' => 1,
  6     'name' => '谢谢参与'
  7 ];

  •  为填充剩余概率的奖品

  三、过滤抽奖、如充值条件

  1 <?php
  2 $pay_total = 7000;
  3 foreach ($prize as $key => $value) {
  4     if($value['pay'] > $pay_total) unset($prize[$key]);
  5 }

  •  初步过滤一些必要因素，比如充值，角色创建时间等

  四、重组概率

   1 <?php
   2 $now_chance = array_sum(array_column($prize, 'chance'));
   3 $remain_chance = 10000 - $now_chance;
   4 $prize[] = ['id' => 0, 'pid' => 0, 'type' => 1, 'name' => '谢谢参与', 'total' => 0, 'chance' => $remain_chance, 'daynum' => 0, 'pay' => 0];
   5  
   6 $award = [];
   7 $num = 0;
   8 foreach ($prize as $_v) {
   9     $num += $_v['chance'];
  10     $award[] = ['id' => $_v['id'], 'pid' => $_v['pid'], 'type' => $_v['type'], 'name' => $_v['name'], 'total' => $_v['total'], 'chance' => $num, 'daynum' => $_v['daynum'], 'pay' => $_v['pay']];
  11 }

  •  初步过滤后，重构新的抽奖信息，加入谢谢参与
  • 第二步重组概率

  五、进行抽奖

   1 <?php
   2 $rand = mt_rand(1, 10000);
   3 $result = [];
   4 foreach ($award as $_k => $_v) {
   5     if ($_k == 0) {
   6         if ($rand > 0 && $rand <= $_v['chance']) {
   7             $result = $_v;
   8             break;
   9         }
  10     } else {
  11         if ($rand > $award[$_k - 1]['chance'] && $rand <= $_v['chance']) {
  12             $result = $_v;
  13             break;
  14         }
  15     }
  16 }

  • 开始抽奖，并返回抽中的结果

  六、过滤回调

   1 <?php
   2 //此处应该查询数据库，查看该奖品已经抽中的数量
   3 $yet_num = 50;
   4 if($result['pid'] != 0 && $yet_num > $result['total']) {
   5     $result = $thanks_prize;
   6 }
   7  
   8 //此处应该查询数据库，查看该奖品今日已经抽中的数量
   9 $yet_today_num = 50;
  10 if($result['pid'] != 0 && $yet_today_num > $result['daynum']) {
  11     $result = $thanks_prize;
  12 }

  • 二次过滤，奖品总数的限制以及奖品的每日限制等 

  七、最终抽奖结果

   1 <?php
   2 //删除敏感字段
   3 unset($result['total'],$result['chance'],$result['daynum'],$result['pay']);
   4  
   5 //返回最终抽奖结果
   6 echo json_encode([
   7     'prize' => $award,
   8     'rand' => $rand,
   9     'result' => $result
  10 ]);

  八、抽奖封装成类

    1 <?php
    2 /**
    3  * Created by PhpStorm.
    4  * User: autofelix
    5  * Date: 2020/10/30
    6  * Time: 13:14
    7  * Desc: 抽奖算法
    8  */
    9  
   10 class Lottery
   11 {
   12     /**
   13      * 概率基数
   14      * @var int
   15      */
   16     private $total_chance = 10000;
   17  
   18     /**
   19      * 谢谢参与奖励
   20      * @var array
   21      */
   22     private $thanks_prize = [
   23         'id' => 0,
   24         'pid' => 0,
   25         'type' => 1,
   26         'name' => '谢谢参与'
   27     ];
   28  
   29     /**
   30      * 奖池
   31      * @var array
   32      */
   33     private $prize = [
   34         ['id' => 1, 'pid' => 11, 'type' => 1, 'name' => '典藏英雄', 'total' => 20, 'chance' => 1000, 'daynum' => 10, 'pay' => 2000 ],
   35         ['id' => 2, 'pid' => 12, 'type' => 1, 'name' => '史诗皮肤', 'total' => 40, 'chance' => 1000, 'daynum' => 10, 'pay' => 4000 ],
   36         ['id' => 3, 'pid' => 13, 'type' => 1, 'name' => '钻石奖励', 'total' => 80, 'chance' => 1000, 'daynum' => 10, 'pay' => 4000 ],
   37         ['id' => 4, 'pid' => 14, 'type' => 1, 'name' => '荣耀水晶', 'total' => 20, 'chance' => 1000, 'daynum' => 10, 'pay' => 8000 ]
   38     ];
   39  
   40     /**
   41      * Lottery constructor.
   42      */
   43     public function __construct()
   44     {
   45     }
   46  
   47     /**
   48      * @return int
   49      */
   50     private function get_user_pay()
   51     {
   52         //这里应该调用接口，返回用户正确的充值信息
   53         return 3000;
   54     }
   55  
   56     /**
   57      * 重构奖池、重组概率
   58      * @return array
   59      */
   60     private function init_lottery_pond()
   61     {
   62         $award = [];
   63  
   64         //充值限制
   65         $user_pay = $this->get_user_pay();
   66         foreach ($this->prize as $key => $value) {
   67             if($value['pay'] <= $user_pay) unset($this->prize[$key]);
   68         }
   69  
   70         //加入谢谢惠顾
   71         $now_chance = array_sum(array_column($this->prize, 'chance'));
   72         $remain_chance = $this->total_chance - $now_chance;
   73         $this->prize[] = ['id' => 0, 'pid' => 0, 'type' => 1, 'name' => '谢谢参与', 'total' => 0, 'chance' => $remain_chance, 'daynum' => 0, 'pay' => 0];
   74  
   75         //重组概率
   76         $num = 0;
   77         foreach ($this->prize as $_v) {
   78             $num += $_v['chance'];
   79             $award[] = ['id' => $_v['id'], 'pid' => $_v['pid'], 'type' => $_v['type'], 'name' => $_v['name'], 'total' => $_v['total'], 'chance' => $num, 'daynum' => $_v['daynum'], 'pay' => $_v['pay']];
   80         }
   81  
   82         return $award;
   83     }
   84  
   85     /**
   86      * 获取抽奖结果
   87      * @return array
   88      */
   89     public function get_prize()
   90     {
   91         $award = $this->init_lottery_pond();
   92         $rand = mt_rand(1, $this->total_chance);
   93         $result = [];
   94         foreach ($award as $_k => $_v) {
   95             if ($_k == 0) {
   96                 if ($rand > 0 && $rand <= $_v['chance']) {
   97                     $result = $_v;
   98                     break;
   99                 }
  100             } else {
  101                 if ($rand > $award[$_k - 1]['chance'] && $rand <= $_v['chance']) {
  102                     $result = $_v;
  103                     break;
  104                 }
  105             }
  106         }
  107  
  108         $result = $this->filter($result);
  109         return $result;
  110     }
  111  
  112     /**
  113      * 抽奖过滤回调函数
  114      * @param $result
  115      * @return array
  116      */
  117     public function filter($result)
  118     {
  119         //奖品总数限制，此处应该查数据库
  120         $yet_num = 50;
  121         if($result['pid'] != 0 && $yet_num > $result['total']) {
  122             $result = $this->thanks_prize;
  123         }
  124  
  125         //奖品每日数量限制，此处应该查数据库
  126         $yet_today_num = 50;
  127         if($result['pid'] != 0 && $yet_today_num > $result['daynum']) {
  128             $result = $this->thanks_prize;
  129         }
  130  
  131         //不暴露敏感信息
  132         unset($result['total'], $result['chance'], $result['daynum'], $result['pay'] );
  133         return $result;
  134     }
  135  
  136     private function __clone()
  137     {
  138     }
  139 }
  140  
  141 echo json_encode((new Lottery())->get_prize());

   

标签：抽奖,pay,pid,daynum,chance,result,total,搞懂,PHP
来源： https://www.cnblogs.com/ypha/p/14123713.html