PHP实现大转盘抽奖算法实例

 1 function get_gift(){  
 2         //拼装奖项数组
 3         // 奖项id，奖品，概率
 4         $prize_arr = array(   
 5           ‘0‘ => array(‘id‘=>1,‘prize‘=>‘平板电脑‘,‘v‘=>0),   
 6           ‘1‘ => array(‘id‘=>2,‘prize‘=>‘数码相机‘,‘v‘=>0),   
 7           ‘2‘ => array(‘id‘=>3,‘prize‘=>‘音箱设备‘,‘v‘=>0),   
 8           ‘3‘ => array(‘id‘=>4,‘prize‘=>‘4G优盘‘,‘v‘=>5),   
 9           ‘4‘ => array(‘id‘=>5,‘prize‘=>‘10Q币‘,‘v‘=>0),   
10           ‘5‘ => array(‘id‘=>6,‘prize‘=>‘空奖‘,‘v‘=>5),   
11         );   
12 
13         foreach ($prize_arr as $key => $val) {   
14           $arr[$val[‘id‘]] = $val[‘v‘];//概率数组           }    
15         $rid = $this->get_rand($arr); //根据概率获取奖项id   
16         $res[‘yes‘] = $prize_arr[$rid-1][‘prize‘]; //中奖项   
17         unset($prize_arr[$rid-1]); //将中奖项从数组中剔除，剩下未中奖项   
18         shuffle($prize_arr); //打乱数组顺序   
19         for($i=0;$i<count($prize_arr);$i++){   
20           $pr[] = $prize_arr[$i][‘prize‘];  //未中奖项数组         }   
21         $res[‘no‘] = $pr;
22         // var_dump($res);
23 
24         if($res[‘yes‘]!=‘空奖‘){  
25             $result[‘status‘]=1;  
26             $result[‘name‘]=$res[‘yes‘];  
27         }else{  
28             $result[‘status‘]=-1;  
29             $result[‘msg‘]=$res[‘yes‘];  
30         }   
31         //return $result;  
32         var_dump($result);
33     }  
34 
35     //计算中奖概率
36     function get_rand($proArr) {   
37       $result = ‘‘;   
38 
39       //概率数组的总概率精度   
40       $proSum = array_sum($proArr);   
41       // var_dump($proSum);
42 
43       //概率数组循环   
44       foreach ($proArr as $key => $proCur) {   
45         $randNum = mt_rand(1, $proSum);  //返回随机整数
46          if ($randNum <= $proCur) {   
47           $result = $key;   
48           break;   
49         } else {   
50           $proSum -= $proCur;   
51         }   
52       }   
53       unset ($proArr);   
54       return $result;   
55     }