public List<BigDecimal> divideRedPacket(BigDecimal totalAmount, int num) { List<BigDecimal> list = new ArrayList<>(); BigDecimal remainingAmount = totalAmount; Random random = new Random(); for (int i = 0; i < num; i++) { if (i == num - 1) { list.add(remainingAmount); } else { BigDecimal maxAmount = remainingAmount.divide(new BigDecimal(num - i), 2, BigDecimal.ROUND_DOWN) .multiply(new BigDecimal("2")); BigDecimal amount = maxAmount.multiply(new BigDecimal(random.nextDouble() + 0.01)) .setScale(2, BigDecimal.ROUND_DOWN); list.add(amount); remainingAmount = remainingAmount.subtract(amount); } } return list; }优化以上代码，要求添加两个参数，两个参数分别控制几个红包的小数点第二位为几

好的，我可以帮您优化这段代码，加入两个参数来控制小数点位数。以下是优化后的代码：

public List<BigDecimal> divideRedPacket(BigDecimal totalAmount, int num, int decimalPlaces, int fixedValue) {
    List<BigDecimal> list = new ArrayList<>();
    BigDecimal remainingAmount = totalAmount;
    Random random = new Random();
    BigDecimal factor = new BigDecimal("10").pow(decimalPlaces);

    for (int i = 0; i < num; i++) {
        if (i == num - 1) {
            list.add(remainingAmount.setScale(decimalPlaces, BigDecimal.ROUND_DOWN));
        } else {
            BigDecimal maxAmount = remainingAmount.divide(new BigDecimal(num - i), decimalPlaces, BigDecimal.ROUND_DOWN)
                .multiply(new BigDecimal("2"));
            BigDecimal amount = maxAmount.multiply(new BigDecimal(random.nextDouble() + 0.01))
                .setScale(decimalPlaces, BigDecimal.ROUND_DOWN);
            if (fixedValue != -1) {
                amount = amount.setScale(decimalPlaces, BigDecimal.ROUND_DOWN);
                amount = amount.setScale(fixedValue, BigDecimal.ROUND_HALF_UP);
            }
            list.add(amount.divide(factor, decimalPlaces, BigDecimal.ROUND_DOWN));
            remainingAmount = remainingAmount.subtract(amount);
        }
    }

    return list;
}

其中，`decimalPlaces` 参数控制小数点后的位数，`fixedValue` 参数控制小数点第二位保留多少位。如果 `fixedValue` 参数为 -1，则不进行保留操作。