如何实现抢红包算法？

方法一：二倍均值法

public static List<Integer> divideRedPackage(Integer totalAmount, Integer totalPeopleNum) {
        List<Integer> amountList = new    ArrayList<Integer>();
        Integer restAmount = totalAmount;
        Integer restPeopleNum = totalPeopleNum;
        Random random = new Random();
        for (int i = 0; i < totalPeopleNum - 1; i++) {
            // 随机范围：[1，剩余人均金额的两倍)，左闭右开
            int amount = random.nextInt(restAmount / restPeopleNum * 2 - 1) + 1;
            restAmount -= amount;
            restPeopleNum--;
            amountList.add(amount);
        }
        amountList.add(restAmount);
        return amountList;
    }

缺陷：除了最后一次，任何一次抢到的金额都不会超过人均金额的两倍，并不是任意的随机

方法二： 线段分割法

实现真正的随机

思路：

①，待分割的数为n，有m个人抢红包，可以随机插入m-1块板，则能将n分成m份

②，将分好组的数进行排序，取出放到list中，则能随机分成m个红包

public static void line_cut(int money,int people ) {
        List<Integer> team=new ArrayList<>();
        List<Integer> result=new ArrayList<>();
        ThreadLocalRandom random=ThreadLocalRandom.current();
        
        int m=money-1;
        while(team.size() < people -1) {
            int nextInt = random.nextInt(m)+1;//不让nextInt 为0
            if(!team.contains(nextInt)) {
                team.add(nextInt);
            }            
        }
        Collections.sort(team);
        System.out.println(team);
       
        for (int i = 0; i < team.size(); i++) {
            if(i== 0) {
                result.add(team.get(i));
            }else {
                result.add(team.get(i)-team.get(i-1));
                if(i==team.size()-1) {
                    result.add(money-team.get(i));
                }
            }
        }
        System.out.println(result);        
        //验证分割后的数是否是输入的总金额
        Optional<Integer> r = result.stream().reduce(Integer::sum);
        System.out.println(r.get());
    }

 

 

 

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