[京东2017实习生笔试] 通过考试

 1 import java.util.Scanner;
 2 
 3 public class Main {
 4 
 5     public static double solve(double[] p) {
 6         final int n = p.length;
 7         double[][] dp = new double[n + 1][n + 1];
 8         dp[0][0] = 1;
 9         for (int i = 1; i <= n; i++) {
10             for (int j = 0; j <= i; j++) {
11                 if (j == 0) {
12                     dp[i][0] = dp[i - 1][0] * (1 - p[i - 1]);
13                 } else {
14                     dp[i][j] = dp[i - 1][j - 1] * p[i - 1] + dp[i - 1][j] * (1 - p[i - 1]);
15                 }
16             }
17         }
18 
19         double ps = 0;
20         for (int i = 0; i <= n; i++) {
21             if (10 * i >= 6 * n) {
22                 ps += dp[n][i];
23             }
24         }
25         return ps;
26     }
27 
28     public static void main(String[] args) {
29         Scanner sc = new Scanner(System.in);
30         int n = sc.nextInt();
31         double[] p = new double[n];
32         for (int i = 0; i < n; i++) {
33             p[i] = (double) sc.nextInt() / 100;
34         }
35         System.out.println(String.format("%.5f", solve(p)));
36     }
37 }