结果

代码

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.ToString;import java.util.ArrayList;
import java.util.List;/****/
public class LotteryUtils {public static void main(String[] args) throws InterruptedException {List<Prize> list = new ArrayList<>();list.add(new Prize(1L, "一等奖", 5));list.add(new Prize(2L, "二等奖", 15));list.add(new Prize(3L, "三等奖", 35));list.add(new Prize(4L, "谢谢回顾", 45)); // 权重越大，几率越高Integer t1 = 0;Integer t2 = 0;Integer t3 = 0;Integer t4 = 0;for (int i = 0; i < 100; i++) {Prize prize = weightFilter(list);if(prize.getId() == 1){t1++;}else if(prize.getId() == 2){t2++;}else if(prize.getId() == 3){t3++;}else{t4++;}}System.out.println("100万次抽结果如下：");System.out.println("一等奖："+t1);System.out.println("二等奖："+t2);System.out.println("三等奖："+t3);System.out.println("谢谢回顾："+t4);}/*** 从一组数据按照概率分布随机取出一个** @param list列表* @return 随机生成的数据的Prize */// 基于权重的随机算法public static Prize weightFilter(List<Prize> list) {// 获取list的权重总数long weight = list.stream().mapToLong(Prize::getWeight).sum();// 在总权重中抽取随机样本int random = (int) Math.floor(Math.random() * weight);for (int j = 0; j < list.size(); j++) {//如果随机样本 < 对象[j] 中指定的概率数值，则认为此次随机 命中在对象[j]上if (random - list.get(j).getWeight() < 0) {return list.get(j);//如果随机样本 > 对象[j] 中指定的概率数值 ，则认为此次随机 未命中在对象[j]上 ，刷新随机样本，继续下次循环} else {random -= list.get(j).getWeight();}}return null;}@Data@ToString@AllArgsConstructorpublic static class Prize {private Long id;private String prizeName;private Integer weight;}}