import java.util.LinkedList;
import java.util.List;
/**
* Function: 模拟微信红包生成，以分为单位
*
* @
author crossoverJie
* Date: 03/01/2018 16:52
* @
since JDK 1.8
*/
public class RedPacket {
/**
* 生成红包最小值 1 分
*/
private static final int MIN_MONEY = 1;
/**
* 生成红包最大值 200 人民币
*/
private static final int MAX_MONEY = 200 * 100;
/**
* 小于最小值
*/
private static final int LESS = -1;
/**
* 大于最大值
*/
private static final int MORE = -2;
/**
* 正常值
*/
private static final int OK = 1;
/**
* 最大的红包是平均值的 TIMES 倍，防止某一次分配红包较大
*/
private static final double TIMES = 2.1F;
private int recursiveCount = 0;
public List<Integer> splitRedPacket(int money, int count) {
List<Integer> moneys = new LinkedList<>();
//金额检查，如果最大红包 * 个数 < 总金额；则需要调大最小红包 MAX_MONEY
if (MAX_MONEY * count <= money) {
System.err.println("请调大最小红包金额 MAX_MONEY=[" + MAX_MONEY + "]");
return moneys ;
}
//计算出最大红包
int max = (int) ((money / count) * TIMES);
max = max > MAX_MONEY ? MAX_MONEY : max;
for (int i = 0; i < count; i++) {
//随机获取红包
int redPacket = randomRedPacket(money, MIN_MONEY, max, count - i);
moneys.add(redPacket);
//总金额每次减少
money -= redPacket;
}
return moneys;
}
private int randomRedPacket(int totalMoney, int minMoney, int maxMoney, int count) {
//只有一个红包直接返回
if (count == 1) {
return totalMoney;
}
if (minMoney == maxMoney) {
return minMoney;
}
//如果最大金额大于了剩余金额 则用剩余金额 因为这个 money 每分配一次都会减小
maxMoney = maxMoney > totalMoney ? totalMoney : maxMoney;
//在 minMoney 到 maxMoney 生成一个随机红包
int redPacket = (int) (Math.random() * (maxMoney - minMoney) + minMoney);
int lastMoney = totalMoney - redPacket;
int status = checkMoney(lastMoney, count - 1);
//正常金额
if (OK == status) {
return redPacket;
}
//如果生成的金额不合法 则递归重新生成
if (LESS == status) {
recursiveCount++;
System.out.println("recursiveCount==" + recursiveCount);
return randomRedPacket(totalMoney, minMoney, redPacket, count);
}
if (MORE == status) {
recursiveCount++;
System.out.println("recursiveCount===" + recursiveCount);
return randomRedPacket(totalMoney, redPacket, maxMoney, count);
}
return redPacket;
}
/**
* 校验剩余的金额的平均值是否在 最小值和最大值这个范围内
*
* @
param lastMoney
* @
param count
* @
return */
private int checkMoney(int lastMoney, int count) {
double avg = lastMoney / count;
if (avg < MIN_MONEY) {
return LESS;
}
if (avg > MAX_MONEY) {
return MORE;
}
return OK;
}
public static void main(String[] args) {
RedPacket redPacket = new RedPacket();
List<Integer> redPackets = redPacket.splitRedPacket(20000, 100);
System.out.println(redPackets);
int sum = 0;
for (Integer red : redPackets) {
sum += red;
}
System.out.println(sum);
}
}
注 引用至:
github.com/crossoverJie