java——抽奖（根据随机值进行抽奖，根据执行范围进行抽奖）

柔光的暖阳◎ 2022-05-14 04:42 227阅读 0赞

如题

下面上货。

需求是这样的，根据不同的概率抽出不同的奖金。

例如：

2%的概率为8

3%的概率为5

5%的概率为3

90%的概率为2

package com.example.demo.demo;
    
    public class LuckyMachine {
        private static int[] money = {8, 5, 3, 2};
        private static double[] probablity = {0.02, 0.03, 0.05, 0.9};
        public static double[] realprobablity;
    
        static {
            realprobablity = new double[probablity.length + 1];
            realprobablity[0] = 0;
            for (int i = 1; i < realprobablity.length; i++) {
                realprobablity[i] = realprobablity[i - 1] + probablity[i - 1];
            }
        }
    
        public static int runLuckyMachine() {
            double k = Math.random();
            System.out.println(k);
            int res = 0;
            for (int i = 0; i < realprobablity.length - 1; i++) {
                double vp = realprobablity[i];
                double vn = realprobablity[i + 1];
                if (vp <= k && k < vn) {
                    res = money[i];
                    break;
                }
            }
            return res;
        }
    
        public static void main(String[] args) {
            for (int i = 0; i < realprobablity.length; i++) {
                double v = realprobablity[i];
                System.out.println(v);
            }
            System.out.println("=====================");
            int a1 = 0;
            int a2 = 0;
            int a3 = 0;
            int a4 = 0;
            for (int i = 0; i < 1000000; i++) {
                int tmp = runLuckyMachine();
                System.out.println(tmp);
                if (tmp == 2) {
                    a1++;
                }
                if (tmp == 3) {
                    a2++;
                }
                if (tmp == 5) {
                    a3++;
                }
                if (tmp == 8) {
                    a4++;
                }
            }
            System.out.println("a1:" + a1);
            System.out.println("a2:" + a2);
            System.out.println("a3:" + a3);
            System.out.println("a4:" + a4);
        }

同样还有依据指定范围进行的：

15% 的概率40-60

30%的概率61-88

40%的概率89-94

15%的概率95-99

package com.example.demo.demo;
    
    import java.util.*;
    
    public class LuckyMachineV2 {
        private static Integer[][] valueArray = {
       {40, 60}, {61, 88}, {89, 94}, {95, 99}};
        private static double[] probablity = {0.15, 0.3, 0.4, 0.15};
        private static double[] realprobablity;
    
        static {
            realprobablity = new double[probablity.length + 1];
            realprobablity[0] = 0;
            for (int i = 1; i < realprobablity.length; i++) {
                realprobablity[i] = realprobablity[i - 1] + probablity[i - 1];
            }
        }
    
        public static List<Integer> runLuckyMachine() {
            double k = Math.random();
            System.out.println(k);
            Integer[] res = null;
            int type = 0;
            for (int i = 0; i < realprobablity.length - 1; i++) {
                double vp = realprobablity[i];
                double vn = realprobablity[i + 1];
                if (vp <= k && k < vn) {
                    type = i;
                    res = valueArray[i];
                    break;
                }
            }
            List<Integer> list = new ArrayList<>();
            if (res != null) {
                list = new ArrayList<>(Arrays.asList(res));
                list.add(type);
            }
            return list;
        }
    
        public static void main(String[] args) {
            Set<Integer> typeSet = new HashSet<>();
            typeSet.add(0);
            List<Integer> list1 = new ArrayList<>();
            List<Integer> list2 = new ArrayList<>();
            List<Integer> list3 = new ArrayList<>();
            List<Integer> list4 = new ArrayList<>();
            while (typeSet.size() == 1) {
                typeSet.clear();
                list1.clear();
                list2.clear();
                list3.clear();
                list4.clear();
                list1 = runLuckyMachine();
                list2 = runLuckyMachine();
                list3 = runLuckyMachine();
                list4 = runLuckyMachine();
                System.out.println(list1);
                System.out.println(list2);
                System.out.println(list3);
                System.out.println(list4);
                typeSet.add(list1.get(2));
                typeSet.add(list2.get(2));
                typeSet.add(list3.get(2));
                typeSet.add(list4.get(2));
                System.out.println("typeSet is " + typeSet);
            }
            int r1 = (int) (Math.random() * (list1.get(1) - list1.get(0))) + list1.get(0);
            int r2 = (int) (Math.random() * (list2.get(1) - list2.get(0))) + list2.get(0);
            int r3 = (int) (Math.random() * (list3.get(1) - list3.get(0))) + list3.get(0);
            int r4 = (int) (Math.random() * (list4.get(1) - list4.get(0))) + list4.get(0);
            System.out.println(r1);
            System.out.println(r2);
            System.out.println(r3);
            System.out.println(r4);
        }
    
    }