版权声明:本文为博主原创文章,未经博主允许不得转载。 https://blog.csdn.net/xiong9999/article/details/85263987
第一版
package com.demo.hongbao;
import java.text.DecimalFormat;
import java.util.Random;
/**
* @ClassName: Main
* @Description: 模拟微信发红包
*/
public class Main {
private static final DecimalFormat FORMAT = new DecimalFormat("######.##");
private static final Random RANDOM = new Random();
public static void main(String[] args) {
String[] redPackage = getRedPackage(20, 11, 0);
for (String red : redPackage) {
double parseDouble = Double.parseDouble(red);
System.out.println(red);
}
}
/**
* @Title: getRedPackage
* @param: totalAmount:总金额
* @param: number:总人数
* @param: minAmount:每人最少的金额,默认为0.01
* @return: String[]
*/
private static String[] getRedPackage(double totalAmount, int number, double minAmount) {
minAmount = minAmount <= 0 ? 0.01 : minAmount;
// amount为随机数种子=总金额-总人数*最少金额
double amount = totalAmount - number * minAmount;
if (totalAmount <= 0 || number < 1 || amount <= 0) {
throw new NumberFormatException("传入参数有误!");
}
String[] everyMoneys = new String[number];
for (int i = 0; i < everyMoneys.length; i++) {
if (amount > 0) {
//获取amount范围内的随机数
String temp = FORMAT.format(RANDOM.nextDouble() * amount);
double parseDouble = Double.parseDouble(temp);
//将amount与最少金额相加,即某一个人的红包金额
everyMoneys[i] = FORMAT.format(minAmount + parseDouble);
//用剩下的钱数,再算随机数
amount -= parseDouble;
} else {
//说明随机数种子已用完
everyMoneys[i] = "" + minAmount;
}
}
return everyMoneys;
}
}
问题
金额分配不够均衡,前几个人金额大,后几个人却很少。
出现原因:在通过种子获取随机数时,刚开始的种子数很大,越往后,种子数越小,最后种子数变为0时,剩余的所有红包全部为最小值。
第二版
package com.demo.hongbao;
import java.text.DecimalFormat;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
/**
* @ClassName: Main
* @Description: 模拟微信发红包
*/
public class Main {
private static final DecimalFormat FORMAT = new DecimalFormat("######.##");
private static final Random RANDOM = new Random();
public static void main(String[] args) {
List<String> redPackage = getRedPackage(10, 20, 0.3);
for (String red : redPackage) {
System.out.println(red);
}
}
/**
* @Title: getRedPackage
* @param: totalAmount:总金额
* @param: number:总人数
* @param: minAmount:每人最少的金额,默认为0.01
* @return: String[]
*/
private static List<String> getRedPackage(double totalAmount, int number, double minAmount) {
if (totalAmount <= 0 || number < 1 || minAmount < 0) {
throw new NumberFormatException("传入参数有误!");
}
minAmount = minAmount == 0 ? 0.01 : minAmount;
List<String> everyMoneys = new ArrayList<>();
//最后一个人的红包=总金额-其他人的红包金额和。所以在循环时,去掉一个人,从1开始
for (int i = 1; i < number; i++) {
//剩余的人数
int remainNumber = number - i;
//最少剩余总金额:每个人至少都分最少的红包金额后的剩余金额
double totalMinAmount = minAmount * remainNumber;
//为了不出现红包分配不均衡的情况,取随机数时的上限为去掉最少剩余总金额的平均数
double tempMax = (totalAmount - totalMinAmount) / remainNumber;
//计算随机数,这个数就是一个红包的金额
String temp = FORMAT.format(RANDOM.nextDouble() * (tempMax - minAmount) + minAmount);
everyMoneys.add(temp);
//总金额-这一次产生的金额,进入下次循环
totalAmount -= Double.parseDouble(temp);
}
//把最后一次的金额加到红包列表中
everyMoneys.add(FORMAT.format(totalAmount));
return everyMoneys;
}
}