今天分享一篇有趣的搶紅包算法，基本原理就是“二倍均值”，簡單說，也就是一個公式，在這里，令P為人數(shù)，M為紅包總金額，那么每次搶到的紅包金額=隨機(jī)區(qū)間（0，P/Mx2），這樣才可以保證每次搶到隨機(jī)金額的均值是相等的。

下面是簡單的代碼：

package Sort_normal;

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

// M:剩餘紅包
// N:剩餘金額
// 每次搶到金額：隨機(jī)區(qū)間[0,M/Nx2]
public class Red_Package {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        System.out.println("請輸入紅包金額：");
        Integer TotalAmount = in.nextInt();
        System.out.println("請輸入人數(shù)：");
        Integer TotalPeople = in.nextInt();
        List<Integer> amountList = RedPackage(TotalAmount, TotalPeople);
//        String[] NameList = new String[]{"小黃", "張三", "李四", "王五", "鶴叔", "麗麗", "小明", "阿杰", "媚姐", "王姨"};
        for (Integer amount : amountList) {
            System.out.println("搶到金額：" + new BigDecimal(amount).divide(new BigDecimal(100)) + "元");
        }
    }

    public static List<Integer> RedPackage(Integer TotalAmount, Integer TotalPeople) {
        List<Integer> amountList = new ArrayList<Integer>();
        Integer restAmount = TotalAmount;//剩餘金額
        Integer restPeople = TotalPeople;//剩餘人數(shù)
        Random random = new Random();
        for (int i = 0; i < TotalPeople - 1; i++) {
            //隨機(jī)範(fàn)圍：[1,剩餘人均金額的兩倍]
            int amount = random.nextInt(restAmount / restPeople * 2 - 1) + 1;
            restAmount -= amount;
            restPeople--;
            amountList.add(amount);
        }
        amountList.add(restAmount);
        return amountList;
    }
}

下面是運行的結(jié)果：

運行結(jié)果