JAVA作业——红包分发

JAVA作业——红包分发

大体思路

如果发总金额为 $m$ 的 $n$ 个红包，先用一个长度为 $n$ 的临时数组 $a$ 存放 $n$ 个随机双精度小数 $(0\le a_i<1)$ ，然后用 $sum$ 表示数组 $a$ 的和，每个红包的金额 $b_i=\frac{a_i}{sum}\cdot m$。

代码

import java.util.Arrays;
import java.util.Random;
import java.math.*;
import java.util.Scanner;

public class Main {
   
    public static long now_time;
    public static long seed;
    public static int[] get_red_packets(int money, int num) {
   
        Random random = new Random(seed);
        seed = random.nextLong();
        int[] res = new int[num];
        double[] temp=new double[num];
        double sum = 0;
        int sum2 = 0;
        for (int i = 0; i < num; i++) {
   
            temp[i] = random.nextDouble();
            sum += temp[i];
        }
        for (int i = 0; i < num; i++) {
   
            res[i] = 1+ (int)(temp[i] / sum * (money-num));
            sum2 += res[i]-1;
        }
        res[random.nextInt(num)]+=money-sum2-num;
        return res;
    }

    public static void show(int[] red_packet){
   
        System.out.println("红包 : " + Arrays.toString(red_packet));
    }

    public static void main(String[] args) {
   
        int num, money;
        Scanner scanner = new Scanner(System.in);
        now_time = System.currentTimeMillis();
        Random init_random = new Random(now_time);
        seed = init_random.nextLong();
        System.out.println("请输入要分发的红包数量:");
        num = scanner.nextInt();
        System.out.println("请输入要分发的红包总金额(分):");
        money = scanner.nextInt();
        int a[] = get_red_packets(money,num);
        show(a);
    }
}