隨機生成紅包演算法
阿新 • • 發佈：2018-11-30
<?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(); //效能測試 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); } //檢查結果 $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".($i+1)."個紅包，金額為：".$val."<br />"; } if ($val == $max) { $max_count++; } if ($val < $min) { $min_count++; } $val = $val*100; $sum += $val; } echo "<pre />";var_dump($reward_arr); //檢測錢是否全部發完 echo '<hr>已生成紅包總金額為：'.($sum/100).';總個數為：'.count($reward_arr).'<hr>'; //檢測有沒有小於0的值 echo "<br />最大值:".($val/100).',共有'.$max_count.'個最大值，共有'.$min_count.'個值比最小值小'; //正態分佈圖 //對紅包進行排序一下以顯示正態分佈特性 $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($show);die; echo "設定最大值為:".$max.',最小值為:'.$min.'<hr />'; echo "<table style='font-size:12px;width:600px;border:1px solid #ccc;text-align:left;'><tr><td>紅包金額</td><td>圖示</td></tr>"; foreach($show as $val) { #線條長度計算 $width=intval($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>";
引入檔案Reward.php
<?php /* * Author:xx_lufei * Time:2016年9月14日09:55:36 * Note:紅包生成隨機演算法 */ class Reward { public $rewardMoney; #紅包金額、單位元 public $rewardNum; #紅包數量 #執行紅包生成演算法 public function splitReward($rewardMoney, $rewardNum, $max, $min) { #傳入紅包金額和數量，因為小數在計算過程中會出現很大誤差，所以我們直接把金額放大100倍，後面的計算全部用整數進行 $min = $min * 100; $max = $max * 100; #預留出一部分錢作為誤差補償，保證每個紅包至少有一個最小值 $this->rewardMoney = $rewardMoney * 100 - $rewardNum * $min; $this->rewardNum = $rewardNum; #計算出發出紅包的平均概率值、精確到小數4位。 $avgRand = 1 / $this->rewardNum; $randArr = array(); #定義生成的資料總合sum $sum = 0; $t_count = 0; while ($t_count < $rewardNum) { #隨機產出四個區間的額度 $c = rand(1, 100); if ($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; } #計算當前生成的隨機數的平均值，保留4位小數 $randAll = round($sum / $rewardNum, 4); #為將生成的隨機數的平均值變成我們要的1/N，計算一下每個隨機數要除以的總基數mixrand。此處可以約等處理，產生的誤差後邊會找齊 #總基數 = 均值/平均概率 $mixrand = round($randAll / $avgRand, 4); #對每一個隨機數進行處理，並乘以總金額數來得出這個紅包的金額。 $rewardArr = array(); foreach ($randArr as $key => $randVal) { #單個紅包所佔比例randVal $randVal = round($randVal / $mixrand, 4); #算出單個紅包金額 $single = floor($this->rewardMoney * $randVal); #小於最小值直接給最小值 if ($single < $min) { $single += $min; } #大於最大值直接給最大值 if ($single > $max) { $single = $max; } #將紅包放入結果陣列 $rewardArr[] = $single; } #對比紅包總數的差異、將差值放在第一個紅包上 $rewardAll = array_sum($rewardArr); $rewardArr[0] = $rewardMoney * 100 - ($rewardAll - $rewardArr[0]);#此處應使用真正的總金額rewardMoney，$rewardArr[0]可能小於0 #第一個紅包小於0時,做修正 if ($rewardArr[0] < 0) { rsort($rewardArr); $this->add($rewardArr, $min); } rsort($rewardArr); #隨機生成的最大值大於指定最大值 if ($rewardArr[0] > $max) { #差額 $diff = 0; foreach ($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 $rewardArr; } #處理所有超過最大值的紅包 public function diff($diff, &$rewardArr, $max, $min, $transfer, $k) { #將多餘的錢均攤給小於最大值的紅包 for ($i = $k; $i < $this->rewardNum; $i++) { #造隨機值 if ($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, $k); } } #第一個紅包小於0,從大紅包上往下減 public function add(&$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); } } }
引入檔案CreateReward.php
<?php
class CreateReward{
/*
* 生成紅包
* author xx 2018年9月23日13:53:38
* @param int $total 紅包總金額
* @param int $num 紅包總數量
* @param int $max 紅包最大值
*
*/
public function random_red($total, $num, $max, $min)
{
#總共要發的紅包金額，留出一個最大值;
$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;
}
}
執行結果
第1個紅包，金額為：6.67
第2個紅包，金額為：7.73
第3個紅包，金額為：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)
}
已生成紅包總金額為：100;總個數為：10