发红包随机金额的两种方式

1 固定面额 即 输入金额生成已知的固定金额

//total  红包总金额   
 protected function randCoupon($total=30){
        $denomination = array(10,5,3,2,1);//固定面额
        $arr = array();
        while ($total){
            if(count($denomination)>0){
                $index = rand(0,count($denomination)-1);//随机抽取一个固定面额索引
                $money = $denomination[$index];
                if($money>$total) continue;
                array_push($arr,$money);
                $total = (int)$total - (int)$money;
                if($total==1){
                    array_push($arr,$total);
                    break;
                }
                if($total<1) break;
                foreach ($denomination as $k => $item){
                    if($total <= $item){
                        array_splice($denomination,$k,1);
                    }
                }
            }

        }
        shuffle($arr);//重新打乱数组
        return $arr;
    }

2 随机金额 即输入金额及红包个数 然后生成一个随机数组

//拆分数值生成若干个和等于该数值随机值
    public function randNum($total=200,$num=17) {
        $min=0.01;//每个人最少能收到0.01元
        for ($i=1;$i<$num;$i++) {
            $safe_total = ($total - ($num-$i)*$min) / ($num-$i);//随机安全上限
            if($safe_total < 0.01) $safe_total = 0.01;
            $money = mt_rand($min*100,$safe_total*100)/100;
            $total = $total - $money;
            $data[] = round($money,2);
        }
        $data[] = round($total,2);
        shuffle($data);
        return $data;
    }