微信随机生成红包金额算法java版

public class WxAlgorithm{ /** * @param moneySum 输入总金额 * @param redNum 输入红包数量 */ private static void wxAlgorithm(double moneySum, int redNum) { // 设置最小的金额 double moneyMin = 0.01; Random random = new Random(); //精确小数点2位 NumberFormat formatter = new DecimalFormat("#.##"); for (int i=1;i<redNum;i++) {  //随机一个数，数值范围在最小值与余额之间  String money = formatter.format(random.nextDouble() * (moneySum - moneyMin) + moneyMin);  //数值转换    moneySum = Double.valueOf(formatter.format(moneySum - Double.valueOf(money)));   System.out.println("第"+i+"个红包：" + money + "元 ,余额：" + moneySum); }  System.out.println("最后个红包：" + moneySum + "元 ,余额：" + (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);//金额，个数，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+"个红包："+money+",余额为:"+total+"元"); } System.out.println("第"+num+"个红包："+total+",余额为: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) {  //红包数  int number = 10;  //红包总额  float total = 100;  float money;  //最小红包  double min = 1;  double max;  int i = 1;  List math = new ArrayList();  DecimalFormat df = new DecimalFormat("###.##");  while (i < number) {   //保证即使一个红包是最大的了,后面剩下的红包,每个红包也不会小于最小值   max = total - min * (number - i);   int k = (int)(number - i) / 2;   //保证最后两个人拿的红包不超出剩余红包   if (number - i <= 2) {    k = number - i;   }   //最大的红包限定的平均线上下   max = max / k;   //保证每个红包大于最小值,又不会大于最大值   money = (int) (min * 100 + Math.random() * (max * 100 - min * 100 + 1));   money = (float)money / 100;   //保留两位小数   money = Float.parseFloat(df.format(money));   total=(int)(total*100 - money*100);   total = total/100;   math.add(money);   System.out.println("第" + i + "个人拿到" + money + "剩下" + total);   i++;   //最后一个人拿走剩下的红包   if (i == number) {    math.add(total);    System.out.println("第" + i + "个人拿到" + total + "剩下0");   }  }//取数组中最大的一个值的索引  System.out.println("本轮发红包中第" + (math.indexOf(Collections.max(math)) + 1) + "个人手气最佳"); }