红包算法，直接看代码

package com.xincai.api.forum.util;

import java.math.BigDecimal;
import java.math.RoundingMode;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;

/**
 * @author: tranquil_chen
 * @Time: 2024/3/5  8:40
 * @description: 红包随机金额生成算法
 */
public class RedPacketUtil {

    /**
     * 分红包算法：二倍均值法
     * @param totalAmount 红包总金额，单位为分
     * @param totalPeopleNum 总人数
     * @return 随机金额数组
     */
    public static List<Double> splitRedpacket(Double totalAmount, Double totalPeopleNum) {
        List<Double> amountList = new ArrayList<Double>();

        if (totalAmount>0 && totalPeopleNum>0){
            Double restAmount = totalAmount * 100;
            Double restPeopleNum = totalPeopleNum;

            Random random = new Random();
            for (int i = 0; i < totalPeopleNum - 1; i++) {
                // 随机范围：[1，剩余人均金额的两倍)，左闭右开

                double amount = random.nextInt((int) (restAmount / restPeopleNum * 2 - 1)) + 1;
                restAmount -= amount;
                restPeopleNum--;
                amountList.add(amount/100);
            }
            amountList.add(restAmount/100);
        }
        return amountList;
    }

    /**
     * 二倍均值法
     */
    public static List<BigDecimal> splitRedpacket(BigDecimal amount, BigDecimal min , BigDecimal num){

        List<BigDecimal> redMoneyList = new ArrayList<>();
        BigDecimal remain = amount.subtract(min.multiply(num));
        final Random random = new Random();
        final BigDecimal hundred = new BigDecimal("100");
        final BigDecimal two = new BigDecimal("2");
        BigDecimal sum = BigDecimal.ZERO;
        BigDecimal redpeck ;
        BigDecimal finalMoney = new BigDecimal(0);
        for (int i = 0; i < num.intValue(); i++) {
            final int nextInt = random.nextInt(100);
            if(i == num.intValue() -1){
                redpeck = remain;
            }else{
                redpeck = new BigDecimal(nextInt).multiply(remain.multiply(two).divide(num.subtract(new BigDecimal(i)),2, RoundingMode.CEILING)).divide(hundred,2, RoundingMode.FLOOR);
            }
            if(remain.compareTo(redpeck) > 0){
                remain = remain.subtract(redpeck);
            }else{
                remain = BigDecimal.ZERO;
            }
            if (i == num.intValue() -1) {
                finalMoney = amount.subtract(sum);
            } else {
                finalMoney = min.add(redpeck).setScale(2, RoundingMode.DOWN);
            }

            sum = sum.add(finalMoney);
            redMoneyList.add(finalMoney);
        }
        return redMoneyList;
    }

    public static void main(String[] args) {
        splitRedpacket(new BigDecimal(10),new BigDecimal(0.1),new BigDecimal(6));
    }
}