求教订单优惠金额均摊问题

1.82 + (20-20.01) = 1.81Copy

<?php

/**
 * WeEngine Document System
 *
 * (c) We7Team 2019 <https://www.w7.cc>
 *
 * This is not a free software
 * Using it under the license terms
 * visited https://www.w7.cc for more details
 */

namespace W7\Sdk\Order\Base\Distributor;

use Webmozart\Assert\Assert;

/**
 * 按比例分摊优惠
 * Class ProportionalIntegerDistributor
 * @package W7\Sdk\Order\Model\Service\Distributor
 */
final class ProportionalIntegerDistributor
{
    /**
     * 分摊优惠
     * @param array|int[] $integers
     * @param int $amount
     * @return array
     */
    public function distribute(array $integers, int $amount): array
    {
        Assert::allInteger($integers);

        $total = array_sum($integers);
        $distributedAmounts = [];

        foreach ($integers as $element) {
            $distributedAmounts[] = (int)round(($element * $amount) / $total, 0, \PHP_ROUND_HALF_DOWN);
        }

        $missingAmount = $amount - array_sum($distributedAmounts);
        for ($i = 0, $iMax = abs($missingAmount); $i < $iMax; ++$i) {
            $distributedAmounts[$i] += $missingAmount >= 0 ? 1 : -1;
        }

        return $distributedAmounts;
    }
}
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