具體如下：
<?php/** 一個抽獎類，精確到萬分之一* 三個步驟：1.接受一個中獎機率數組;2.接受一個抽獎種子;3.返回中獎等級*/class Lottery {/** 中獎機率數組，自動判斷獎項數目* 數組索引值和為100，自動計算出不中獎的機率，若初始是超過100拋出一個錯誤*/protected $_rate = array();/** 設定中獎機率，* @param Array,中獎機率，以數組形式傳入*/public function setRate($rate = array(12.1, 34)) {$this->_rate = $rate;if (array_sum($this->_rate) > 100)//檢測機率設定是否有問題throw new Exception('Winning rate upto 100%');if (array_sum($this->_rate) < 100)//定義未中獎情況的機率，使用者給的機率只和為100時，則忽略0$this->_rate[] = 100 - array_sum($this->_rate);}/** 隨機產生一個1-10000的整數種子，提交給中獎判斷函數* @return int,按傳入的機率排序，返回中獎的項數*/public function runOnce() {return $this->judge(mt_rand(0, 10000));}/** 按所設定的機率，判斷一個傳入的隨機值是否中獎* @param int,$seed 10000以內的隨機數* @return int,$i 按傳入的機率排序，返回中獎的項數*/protected function judge($seed) {foreach ($this->_rate as $key => $value) {$tmpArr[$key + 1] = $value * 100;}//將機率乘十後累計，以便隨機播放，組合成$tmpArr[0] = 0;foreach ($tmpArr as $key => $value) {if ($key > 0) {$tmpArr[$key] += $tmpArr[$key - 1];}}for ($i = 1; $i < count($tmpArr); $i++) {if ($tmpArr[$i - 1] < $seed && $seed <= $tmpArr[$i]) {return $i; //返回中獎的項數（按機率的設定順序）}}}}$rate = array(33, 20, 2, 0.95, 12, 4.55);$a = new Lottery;$a->setRate($rate);for ($i = 0; $i <= 10000; $i++) {$b = $a->runOnce();@$rewards[$b]++;}unset($rewards['']);echo array_sum($rewards);?><html><head><meta http-equiv="Content-Type" content="text/html; charset=utf8" /></head><body><table><thead>運行10000次，對比設定機率和中獎次數</thead><tr><th>設定機率</th><th>中獎次數</th></tr><tr><td><?php echo $rate[0]; ?>%</td><td><?php echo $rewards[1] ?></td></tr><tr><td><?php echo $rate[1]; ?>%</td><td><?php echo $rewards[2] ?></td></tr><tr><td><?php echo $rate[2]; ?>%</td><td><?php echo $rewards[3] ?></td></tr><tr><td><?php echo $rate[3]; ?>%</td><td><?php echo $rewards[4] ?></td></tr><tr><td><?php echo $rate[4]; ?>%</td><td><?php echo $rewards[5] ?></td></tr><tr><td><?php echo $rate[5]; ?>%</td><td><?php echo $rewards[6] ?></td></tr><tr><td><?php echo 'miss'; ?></td><td><?php echo $rewards[7] ?></td></tr></table></body></html>
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