股票雷达Raquant笔试题

空闲之作，相互学习^_^

题目要求：

1、生成五千行文本文件；

2、其中每一行分成3列，每一列是一个随机数，取值1到100的整数；

3、读取生成的文件，算出三列全是偶数的行数与三列全是奇数的行数的比值；

4、重复1到3的步骤，重复50遍，打印出50个数，计算这50个数的标准差。

 1 public class testWork {
 2
 3     // 得50个数
 4     public double[] db() {
 5
 6         int evenNum = 0;
 7         int oddNum = 0; // jishu
 8
 9         int count_all_even = 0;
10         int count_all_odd = 0;
11
12         int arr[][] = new int[5000][3];
13         double db[] = new double[50];
14
15         for (int h = 0; h < 50; h++) {
16             System.out.println("第"+(h+1)+"遍输出5000行数据");
17             for (int i = 0; i < 5000; i++) {
18
19                 for (int j = 0; j < 3; j++) {
20
21                     arr[i][j] = (int) (Math.random() * 100);
22
23                     if (j == 2) {
24                         System.out.println(arr[i][0] + " " + arr[i][1] + " "
25                                 + arr[i][2]);
26                     }
27
28                     if (arr[i][j] % 2 == 0) {
29                         evenNum++;
30                     } else {
31                         oddNum++;
32                     }
33                 }
34
35 //                System.out.println(evenNum + " " + oddNum);
36
37                 if (evenNum == 3) {
38                     count_all_even++;
39                 }
40                 if (oddNum == 3) {
41                     count_all_odd++;
42                 }
43
44                 evenNum = 0;
45                 oddNum = 0;
46
47             }
48 //            System.out.println(count_all_even + " " + count_all_odd);
49             db[h] = (double) count_all_even / count_all_odd;
50 //            System.out.println("第"+(h+1)+"遍count_all_even / count_all_odd的比值为" + " : " + db[h]);
51
52             count_all_even = 0;
53             count_all_odd = 0;
54         }
55         return db;
56     }
57
58     // 获取平均值
59     public double getAverage(double db[]) {
60         int sum = 0;
61         for (int i = 0; i < db.length; i++) {
62             sum += db[i];
63         }
64         return (double) (sum / db.length);
65     }
66
67     // 获取标准差
68     public double getStandardDevition(double db[]) {
69         double sum = 0;
70         for (int i = 0; i < db.length; i++) {
71             sum += Math.sqrt(((double) db[i] - getAverage(db))
72                     * (db[i] - getAverage(db)));
73         }
74         return (sum / (db.length - 1));
75     }
76
77     public static void main(String[] args) {
78
79         testWork tw = new testWork();
80
81         double x = 0.0;
82
83         double db[]=tw.db();
84
85         for(int i=0;i<50;i++){
86             System.out.println("第"+(i+1)+"遍count_all_even / count_all_odd的比值为" + " : " + db[i]);
87         }
88
89         x = tw.getStandardDevition(db);
90         System.out.println("50个数的标准差为: "+x);
91     }
92
93 }

结果如下：