php 抽奖概率 随机数

<?php

$prize_arr = array(
    '0' => array('id' => 1, 'title' => 'iphone5s', 'v' => 5),
    '1' => array('id' => 2, 'title' => '联系笔记本', 'v' => 10),
    '2' => array('id' => 3, 'title' => '音箱设备', 'v' => 20),
    '3' => array('id' => 4, 'title' => '30GU盘', 'v' => 30),
    '4' => array('id' => 5, 'title' => '话费50元', 'v' => 10),
    '5' => array('id' => 6, 'title' => 'iphone6s', 'v' => 15),
    '6' => array('id' => 7, 'title' => '谢谢，继续加油哦！~', 'v' => 10),
); 

foreach ($prize_arr as $key => $val) {
    $arr[$val['id']] = $val['v'];
} 

$prize_id = getRand($arr); //根据概率获取奖品id
$data['msg'] = ($prize_id == 7) ? 0 : 1; //如果为0则没中
$data['prize_title'] = $prize_arr[$prize_id - 1]['title']; //中奖奖品
echo json_encode($data);
exit; //以json数组返回给前端 

function getRand($proArr) { //计算中奖概率
    $rs = ''; //z中奖结果
    $proSum = array_sum($proArr); //概率数组的总概率精度
    //概率数组循环
    foreach ($proArr as $key => $proCur) {
        $randNum = mt_rand(1, $proSum);
        if ($randNum <= $proCur) {
            $rs = $key;
            break;
        } else {
            $proSum -= $proCur;
        }
    }
    unset($proArr);
    return $rs;
}

?>
=========================================

<?php
header("Content-Type: text/html; charset=utf-8");
$prize_arr = array(
'0' => array('id' => 1, 'url' => 'http://mp.weixin.qq.com/s/hyPRO4tJAl1cJaY97TGFvw', 'v' => 5),
'1' => array('id' => 2, 'url' => 'http://mp.weixin.qq.com/s/gD2MhdYAMx1PyA4jCdJtQQ', 'v' => 10),
'2' => array('id' => 3, 'url' => 'http://mp.weixin.qq.com/s/Ud_F_l6ZufGElkZwONzGbA', 'v' => 20),
'3' => array('id' => 4, 'url' => 'http://mp.weixin.qq.com/s/LA1lASoxuRdaZ13F8pQbNA', 'v' => 30),
'4' => array('id' => 5, 'url' => 'http://mp.weixin.qq.com/s/efZKG9GjrchhBR4zT5zU3A', 'v' => 10),
'5' => array('id' => 6, 'url' => 'http://mp.weixin.qq.com/s/ghisPsLG4OIFdehn6kZrUw', 'v' => 15),
'6' => array('id' => 7, 'url' => 'http://mp.weixin.qq.com/s/bltFJBXstWN43r0GiePzBw', 'v' => 10),
);
// echo "呵呵";
foreach ($prize_arr as $key => $val) {
$arr[$val['id']] = $val['v'];
}
// var_dump($arr);

$myid = myword($arr);
$data['url'] = $prize_arr[$myid-1]['url'];
$url = $data['url'];
echo "<script type='text/javascript'>window.location.href='$url';</script>";

function myword($str){
$rs = '';//中奖结果

$proSum = array_sum($str);//计算数组中所有值的和
//概率数组循环
foreach ($str as $k => $v) {
$word1 = mt_rand(1,$proSum); //生成更好的随机数
if( $word1 <= $v){
$rs = $k;
break;
}else{
$proSum -= $v;
}
}

return $rs;
}

?>