随机生成红包算法
<?php /** * Created by PhpStorm. * User: kevin_yang * Date: 2018/1/4 * Time: 22:49 */ header('content-type:text/html;charset=utf-8'); ini_set('memory_limit', '256M'); require_once('CreateReward.php'); require_once('Reward.php'); $total = 100; $num = 10; $max = mt_rand(1,2)*(ceil($total/$num)); $min = 0.1; $create_reward = new CreateReward(); //性能测试 for($i=0; $i<5; $i++) { $time_start = microtime_float(); $reward_arr = $create_reward->random_red($total, $num, $max, $min); $time_end = microtime_float(); $time[] = $time_end - $time_start; } //echo array_sum($time)/5; function microtime_float() { list($usec, $sec) = explode(" ", microtime()); return ((float)$usec + (float)$sec); } //检查结果 $reward_arr = $create_reward->random_red($total, $num, $max, $min); sort($reward_arr);//正序，最小的在前面 $sum = 0; $min_count = 0; $max_count = 0; foreach($reward_arr as $i => $val) { if ($i<3) { echo "<br />第".($i+1)."个红包，金额为：".$val."<br />"; } if ($val == $max) { $max_count++; } if ($val < $min) { $min_count++; } $val = $val*100; $sum += $val; } echo "<pre />";var_dump($reward_arr); //检测钱是否全部发完 echo '<hr>已生成红包总金额为：'.($sum/100).';总个数为：'.count($reward_arr).'<hr>'; //检测有没有小于0的值 echo "<br />最大值:".($val/100).',共有'.$max_count.'个最大值，共有'.$min_count.'个值比最小值小'; //正态分布图 //对红包进行排序一下以显示正态分布特性 $reward_arr = $create_reward->random_red($total, $num, $max, $min); $show = array(); rsort($reward_arr); foreach($reward_arr as $k=>$value) { $t=$k%2; if(!$t) $show[]=$value; else array_unshift($show,$value); } //echo "<pre>";var_dump($show);die; echo "设定最大值为:".$max.',最小值为:'.$min.'<hr />'; echo "<table style='font-size:12px;width:600px;border:1px solid #ccc;text-align:left;'><tr><td>红包金额</td><td>图示</td></tr>"; foreach($show as $val) { #线条长度计算 $width=intval($num*$val*300/$total); echo "<tr><td> {$val} </td><td width='500px;text-align:left;'><hr style='width:{$width}px;height:3px;border:none;border-top:3px double red;margin:0 auto 0 0px;'></td></tr>"; } echo "</table>";
引入文件Reward.php
<?php /* * Author:xx_lufei * Time:2016年9月14日09:55:36 * Note:红包生成随机算法 */ class Reward { public $rewardMoney; #红包金额、单位元 public $rewardNum; #红包数量 #执行红包生成算法 public function splitReward($rewardMoney, $rewardNum, $max, $min) { #传入红包金额和数量，因为小数在计算过程中会出现很大误差，所以我们直接把金额放大100倍，后面的计算全部用整数进行 $min = $min * 100; $max = $max * 100; #预留出一部分钱作为误差补偿，保证每个红包至少有一个最小值 $this->rewardMoney = $rewardMoney * 100 - $rewardNum * $min; $this->rewardNum = $rewardNum; #计算出发出红包的平均概率值、精确到小数4位。 $avgRand = 1 / $this->rewardNum; $randArr = array(); #定义生成的数据总合sum $sum = 0; $t_count = 0; while ($t_count < $rewardNum) { #随机产出四个区间的额度 $c = rand(1, 100); if ($c < 15) { $t = round(sqrt(mt_rand(1, 1500))); } else if ($c < 65) { $t = round(sqrt(mt_rand(1500, 6500))); } else if ($c < 95) { $t = round(sqrt(mt_rand(6500, 9500))); } else { $t = round(sqrt(mt_rand(9500, 10000))); } ++$t_count; $sum += $t; $randArr[] = $t; } #计算当前生成的随机数的平均值，保留4位小数 $randAll = round($sum / $rewardNum, 4); #为将生成的随机数的平均值变成我们要的1/N，计算一下每个随机数要除以的总基数mixrand。此处可以约等处理，产生的误差后边会找齐 #总基数 = 均值/平均概率 $mixrand = round($randAll / $avgRand, 4); #对每一个随机数进行处理，并乘以总金额数来得出这个红包的金额。 $rewardArr = array(); foreach ($randArr as $key => $randVal) { #单个红包所占比例randVal $randVal = round($randVal / $mixrand, 4); #算出单个红包金额 $single = floor($this->rewardMoney * $randVal); #小于最小值直接给最小值 if ($single < $min) { $single += $min; } #大于最大值直接给最大值 if ($single > $max) { $single = $max; } #将红包放入结果数组 $rewardArr[] = $single; } #对比红包总数的差异、将差值放在第一个红包上 $rewardAll = array_sum($rewardArr); $rewardArr[0] = $rewardMoney * 100 - ($rewardAll - $rewardArr[0]);#此处应使用真正的总金额rewardMoney，$rewardArr[0]可能小于0 #第一个红包小于0时,做修正 if ($rewardArr[0] < 0) { rsort($rewardArr); $this->add($rewardArr, $min); } rsort($rewardArr); #随机生成的最大值大于指定最大值 if ($rewardArr[0] > $max) { #差额 $diff = 0; foreach ($rewardArr as $k => &$v) { if ($v > $max) { $diff += $v - $max; $v = $max; } else { break; } } $transfer = round($diff / ($this->rewardNum - $k + 1)); $this->diff($diff, $rewardArr, $max, $min, $transfer, $k); } return $rewardArr; } #处理所有超过最大值的红包 public function diff($diff, &$rewardArr, $max, $min, $transfer, $k) { #将多余的钱均摊给小于最大值的红包 for ($i = $k; $i < $this->rewardNum; $i++) { #造随机值 if ($transfer > $min * 20) { $aa = rand($min, $min * 20); if ($i % 2) { $transfer += $aa; } else { $transfer -= $aa; } } if ($rewardArr[$i] + $transfer > $max) continue; if ($diff - $transfer < 0) { $rewardArr[$i] += $diff; $diff = 0; break; } $rewardArr[$i] += $transfer; $diff -= $transfer; } if ($diff > 0) { $i++; $this->diff($diff, $rewardArr, $max, $min, $transfer, $k); } } #第一个红包小于0,从大红包上往下减 public function add(&$rewardArr, $min) { foreach ($rewardArr as &$re) { $dev = floor($re / $min); if ($dev > 2) { $transfer = $min * floor($dev / 2); $re -= $transfer; $rewardArr[$this->rewardNum - 1] += $transfer; } elseif ($dev == 2) { $re -= $min; $rewardArr[$this->rewardNum - 1] += $min; } else { break; } } if ($rewardArr[$this->rewardNum - 1] > $min || $rewardArr[$this->rewardNum - 1] == $min) { return; } else { $this->add($rewardArr, $min); } } }
引入文件CreateReward.php
<?php
class CreateReward{
/*
* 生成红包
* author xx 2018年9月23日13:53:38
* @param int $total 红包总金额
* @param int $num 红包总数量
* @param int $max 红包最大值
*
*/
public function random_red($total, $num, $max, $min)
{
#总共要发的红包金额，留出一个最大值;
$total = $total - $max;
$reward = new Reward();
$result_merge = $reward->splitReward($total, $num, $max - 0.01, $min);
sort($result_merge);
$result_merge[1] = $result_merge[1] + $result_merge[0];
$result_merge[0] = $max * 100;
foreach ($result_merge as &$v) {
$v = floor($v) / 100;
}
return $result_merge;
}
}
运行结果
第1个红包，金额为：6.67
第2个红包，金额为：7.73
第3个红包，金额为：7.83
array(10) {
[0]=>
float(6.67)
[1]=>
float(7.73)
[2]=>
float(7.83)
[3]=>
float(8.46)
[4]=>
float(8.89)
[5]=>
float(9.21)
[6]=>
float(10.15)
[7]=>
float(10.48)
[8]=>
float(10.58)
[9]=>
float(20)
}
已生成红包总金额为：100;总个数为：10
