zoj 3827(牡丹江区域赛 I题 )

套公式

Sample Input

3
3 bit
25 25 50 //百分数
7 nat
1 2 4 8 16 32 37
10 dit
10 10 10 10 10 10 10 10 10 10
Sample Output

1.500000000000
1.480810832465
1.000000000000

 1 # include <iostream>
 2 # include <cstdio>
 3 # include <cstring>
 4 # include <algorithm>
 5 # include <cmath>
 6 # include <queue>
 7 # define LL long long
 8 using namespace std ;
 9
10 char s[10] ;
11 const double esp = 1e-9;
12
13 int main ()
14 {
15     //freopen("in.txt","r",stdin) ;
16     int T ;
17     scanf("%d" , &T) ;
18     while(T--)
19     {
20         int n ;
21         double  p , b ;
22         scanf("%d %s" , &n , s) ;
23         if (s[0] == ‘b‘)
24             b = 2 ;
25         else if (s[0] == ‘n‘)
26             b = exp(1.0) ;
27         else
28             b = 10 ;
29         int i ;
30         double ans = 0 ;
31         for (i = 0 ; i < n ; i++)
32         {
33             scanf("%lf" , &p) ;
34             if (fabs(p) > esp)
35             {
36                 p /= 100.0;
37                 ans += p * log(p) / log(b);
38             }
39
40         }
41         printf("%.12lf\n" , -ans) ;
42
43     }
44
45     return 0 ;
46 }