php 抽奖概率算法

<?php
function drawPrize($probabilities) {
    $total = array_sum($probabilities);
    $rand = mt_rand(1, $total);

    $sum = 0;
    foreach ($probabilities as $key => $probability) {
        $sum += $probability;
        if ($rand <= $sum) {
            return $key;
        }
    }
}

$probabilities = [
    '一等奖' => 1, // 1%
    '二等奖' => 5, // 5%
    '三等奖' => 20, // 20%
    '谢谢参与' => 74 // 74%
];

$result = drawPrize($probabilities);
echo "恭喜你获得了: " . $result;
?>