//最小红包额度 
private static final int MINMONEY = 1; 
//最大红包额度 
private static final int MAXMONEY = 200 * 100; 

private boolean isRight(int money, int count) { 
 double avg = money / count; 
 if (avg < MINMONEY) { 
 return false; 
 } 
 if (avg > MAXMONEY) { 
 return false; 
 } 
 return true; 
} 

private int random(int money, int minS, int maxS, int count) { 
 //红包数量为1，直接返回金额 
 if (count == 1) { 
 return money; 
 } 
 //如果最大金额和最小金额相等，直接返回金额 
 if (minS == maxS) { 
 return minS; 
 } 
 int max = maxS > money ? money : maxS; 
 //随机产生一个红包 
 int one = ((int)Math.rint(Math.random() * (max - minS) + minS)) % max + 1; 
 int money1 = money - one; 
 //判断该种分配方案是否正确 
 if (isRight(money1, count -1)) { 
 return one; 
 } else { 
 double avg = money1 / (count - 1); 
 if (avg < MINMONEY) { 
 //递归调用，修改红包最大金额 
 return random(money, minS, one, count); 
 }else if (avg > MAXMONEY) { 
 //递归调用，修改红包最小金额 
 return random(money, one, maxS, count); 
 } 
 } 
 return one; 
} 

//每个红包最大是平均值的倍数 
private static final double TIMES = 2.1; 
 
public List<Integer> splitRedPackets(int money, int count) { 
 if (!isRight(money, count)) { 
 return null; 
 } 
 List<Integer> list = new ArrayList<Integer>(); 
 //红包最大金额为平均金额的TIMES倍 
 int max = (int) (money * TIMES / count); 
 max = max > MAXMONEY ? MAXMONEY : max; 
 for (int i = 0; i < count; i++) { 
 int one = random(money, MINMONEY, max, count - i); 
 list.add(one); 
 money -= one; 
 } 
 return list; 
} 

 /** 
 *@Description: 
 */ 
package com.lulei.weixin.util; 
 
import java.util.ArrayList; 
import java.util.List; 
 
import com.lulei.util.JsonUtil; 
 
public class RedPacketUtil { 
 //最小红包额度 
 private static final int MINMONEY = 1; 
 //最大红包额度 
 private static final int MAXMONEY = 200 * 100; 
 //每个红包最大是平均值的倍数 
 private static final double TIMES = 2.1; 
 
 /** 
 * @param money 
 * @param count 
 * @return 
 * @Author:lulei 
 * @Description: 拆分红包 
 */ 
 public List<Integer> splitRedPackets(int money, int count) { 
 if (!isRight(money, count)) { 
 return null; 
 } 
 List<Integer> list = new ArrayList<Integer>(); 
 //红包最大金额为平均金额的TIMES倍 
 int max = (int) (money * TIMES / count); 
 max = max > MAXMONEY ? MAXMONEY : max; 
 for (int i = 0; i < count; i++) { 
 int one = random(money, MINMONEY, max, count - i); 
 list.add(one); 
 money -= one; 
 } 
 return list; 
 } 
 
 /** 
 * @param money 
 * @param minS 
 * @param maxS 
 * @param count 
 * @return 
 * @Author:lulei 
 * @Description: 随机红包额度 
 */ 
 private int random(int money, int minS, int maxS, int count) { 
 //红包数量为1，直接返回金额 
 if (count == 1) { 
 return money; 
 } 
 //如果最大金额和最小金额相等，直接返回金额 
 if (minS == maxS) { 
 return minS; 
 } 
 int max = maxS > money ? money : maxS; 
 //随机产生一个红包 
 int one = ((int)Math.rint(Math.random() * (max - minS) + minS)) % max + 1; 
 int money1 = money - one; 
 //判断该种分配方案是否正确 
 if (isRight(money1, count -1)) { 
 return one; 
 } else { 
 double avg = money1 / (count - 1); 
 if (avg < MINMONEY) { 
 //递归调用，修改红包最大金额 
 return random(money, minS, one, count); 
 }else if (avg > MAXMONEY) { 
 //递归调用，修改红包最小金额 
 return random(money, one, maxS, count); 
 } 
 } 
 return one; 
 } 
 
 /** 
 * @param money 
 * @param count 
 * @return 
 * @Author:lulei 
 * @Description: 此种红包是否合法 
 */ 
 private boolean isRight(int money, int count) { 
 double avg = money / count; 
 if (avg < MINMONEY) { 
 return false; 
 } 
 if (avg > MAXMONEY) { 
 return false; 
 } 
 return true; 
 } 
 
 public static void main(String[] args) { 
 // TODO Auto-generated method stub 
 RedPacketUtil util = new RedPacketUtil(); 
 System.out.println(JsonUtil.parseJson(util.splitRedPackets(20000, 100))); 
 } 
}