PHP抽奖中奖概率算法设计

做项目的时候涉及到抽奖概率的设置，以下是php实现中奖抽奖概率的计算算法，供大家参考

一、中奖概率方法：可以看到设置了每个中奖概率，合计中奖概率为100%

<?php
 public function gl(){
	$prize_arr = [
			'0' => ['id' => 1, 'prize' => '奖品1', 'v' => 20],
			'1' => ['id' => 2, 'prize' => '奖品2', 'v' => 10],
			'2' => ['id' => 3, 'prize' => '奖品3', 'v' => 20],
			'3' => ['id' => 4, 'prize' => '奖品4', 'v' => 5],
			'4' => ['id' => 5, 'prize' => '奖品5', 'v' => 19],
			'5' => ['id' => 6, 'prize' => '奖品6', 'v' => 5],
			'6' => ['id' => 7, 'prize' => '奖品7', 'v' => 10],
			'7' => ['id' => 8, 'prize' => '奖品8', 'v' => 10],
		];
  
	foreach ($prize_arr as $key => $val) {
		$arr[$val['id']] = $val['v'];
	}
 
	$rid = $this->get_prize($arr); //根据概率获取奖项id
	$data = $prize_arr[$rid-1];
	return json($data);
 
}

二、对概率进行计算

<?php
public function get_prize($proArr) {
	$result = '';
	//概率数组的总概率精度
	$proSum = array_sum($proArr);
	//概率数组循环
	foreach ($proArr as $key => $proCur) {
		$randNum = mt_rand(1, $proSum);
		if ($randNum <= $proCur) {
			$result = $key;
			break;
		} else {
			$proSum -= $proCur;
		}
	}
	unset ($proArr);
	return $result;
}
?>