public class WxAlgorithm{

 /**
 * @param moneySum 輸入總金額
 * @param redNum 輸入紅包數(shù)量
 */
 private static void wxAlgorithm(double moneySum, int redNum) {
 // 設(shè)置最小的金額
 double moneyMin = 0.01;
 Random random = new Random();
 //精確小數(shù)點(diǎn)2位
 NumberFormat formatter = new DecimalFormat("#.##");
 for (int i=1;i<redNum;i++)
 {
 //隨機(jī)一個數(shù)，數(shù)值范圍在最小值與余額之間
 String money = formatter.format(random.nextDouble() * (moneySum - moneyMin) + moneyMin);
 //數(shù)值轉(zhuǎn)換
  moneySum = Double.valueOf(formatter.format(moneySum - Double.valueOf(money)));
 
 System.out.println("第"+i+"個紅包：" + money + "元 ,余額：" + moneySum);
 }
 
 System.out.println("最后個紅包：" + moneySum + "元 ,余額：" + (moneySum - moneySum));
 }
 
 public static void main(String[] args) {
 wxAlgorithm(10.26, 9);
 }
}

public static double [] getMoney(double money, int num){
 Random r = new Random();
 DecimalFormat format = new DecimalFormat(".##");
 
 double middle = Double.parseDouble(format.format(money/num));
 double [] dou = new double[num];
 double redMoney = 0;
 double nextMoney = money;
 double sum = 0;
 int index = 0;
 for(int i=num;i>0;i--){
  if(i == 1){
  dou[index] = nextMoney;
  }else{
  while(true){
   String str = format.format(r.nextDouble()*nextMoney);
   redMoney = Double.parseDouble(str);
   if(redMoney>0 && redMoney < middle){
   break;
   }
  }
  nextMoney = Double.parseDouble(format.format(nextMoney - redMoney));
  sum = sum + redMoney;
  dou[index] = redMoney;
  middle = Double.parseDouble(format.format(nextMoney/(i-1)));
  index++;
  }
 }
 return dou;
 }

package com.sunron.test;

import java.math.BigDecimal;

import org.junit.Test;

public class HongBao {
 @Test
 public void testHonbao(){
 hb(100, 9, 0.01);//金額，個數(shù)，最少值
 //zb();
 }
 void hb(double total,int num,double min){
 for(int i=1;i<num;i++){
 double safe_total=(total-(num-i)*min)/(num-i);
 double money=Math.random()*(safe_total-min)+min;
 BigDecimal money_bd=new BigDecimal(money);
 money=money_bd.setScale(2,BigDecimal.ROUND_HALF_UP).doubleValue(); 
 total=total-money;
 BigDecimal total_bd=new BigDecimal(total);
 total=total_bd.setScale(2,BigDecimal.ROUND_HALF_UP).doubleValue();
 System.out.println("第"+i+"個紅包："+money+",余額為:"+total+"元");
 }
 System.out.println("第"+num+"個紅包："+total+",余額為:0元");
 }
 
 void zb(){
  for(int a=0;a<=10000;a++){
  if(a % 1000== 0) 
  System.out.println (a);
  }
 
 }

}

public static void main(String[] args) {
 //紅包數(shù)
 int number = 10;
 //紅包總額
 float total = 100;
 float money;
 //最小紅包
 double min = 1;
 double max;
 int i = 1;
 List math = new ArrayList();
 DecimalFormat df = new DecimalFormat("###.##");
 while (i < number) {
  //保證即使一個紅包是最大的了,后面剩下的紅包,每個紅包也不會小于最小值
  max = total - min * (number - i);
  int k = (int)(number - i) / 2;
  //保證最后兩個人拿的紅包不超出剩余紅包
  if (number - i <= 2) {
  k = number - i;
  }
  //最大的紅包限定的平均線上下
  max = max / k;
  //保證每個紅包大于最小值,又不會大于最大值
  money = (int) (min * 100 + Math.random() * (max * 100 - min * 100 + 1));
  money = (float)money / 100;
  //保留兩位小數(shù)
  money = Float.parseFloat(df.format(money));
  total=(int)(total*100 - money*100);
  total = total/100;
  math.add(money);
  System.out.println("第" + i + "個人拿到" + money + "剩下" + total);
  i++;
  //最后一個人拿走剩下的紅包
  if (i == number) {
  math.add(total);
  System.out.println("第" + i + "個人拿到" + total + "剩下0");
  }
 }
//取數(shù)組中最大的一個值的索引
 System.out.println("本輪發(fā)紅包中第" + (math.indexOf(Collections.max(math)) + 1) + "個人手氣最佳");
 }