抢红包算法

今天分享一篇有趣的抢红包算法，基本原理就是“二倍均值”，简单说，也就是一个公式，在这里，令P为人数，M为红包总金额，那么每次抢到的红包金额=随机区间（0，P/Mx2），这样才可以保证每次抢到随机金额的均值是相等的。

下面是简单的代码：

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：隨機區間[0,M/Nx2]
public class Red_Package {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        System.out.println("请输入红包金额：");
        Integer TotalAmount = in.nextInt();
        System.out.println("请输入人数：");
        Integer TotalPeople = in.nextInt();
        List<Integer> amountList = RedPackage(TotalAmount, TotalPeople);
//        String[] NameList = new String[]{"小黄", "张三", "李四", "王五", "鹤叔", "丽丽", "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
        Random random = new Random();
        for (int i = 0; i < TotalPeople - 1; i++) {
            //隨機範圍：[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;
    }
}

下面是运行的结果：