ZOJ3827——Information Entropy

http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemCode=3827

/*
输出用f
*/
/************************************************
* Author        :Powatr
* Created Time  :2015-8-18 10:37:09
* File Name     :ZOJ2827.cpp
 ************************************************/

#include <cstdio>
#include <algorithm>
#include <iostream>
#include <sstream>
#include <cstring>
#include <cmath>
#include <string>
#include <vector>
#include <queue>
#include <deque>
#include <stack>
#include <list>
#include <map>
#include <set>
#include <bitset>
#include <cstdlib>
#include <ctime>
using namespace std;

#define lson l, mid, rt << 1
#define rson mid + 1, r, rt << 1 | 1
typedef long long ll;
const int MAXN = 100 + 10;
const int INF = 0x3f3f3f3f;
const int MOD = 1e9 + 7;

int main(){
    int n; char s[10]; 
    int a[MAXN];
    int T;
    scanf("%d", &T);
    while(T--){
    double ans = 0.0;
        scanf("%d%s", &n, s);
        for(int i = 1; i <= n; i++)
            scanf("%d", &a[i]);
        for(int i = 1; i <= n; i++){
            if(a[i] == 0) continue;
           double res = (double)(1.0*a[i]*(1.0*log(1.0*a[i]/100))/100);
            if(s[0] == 'b')
                res = (double)res/(1.0*log(2.0));
            if(s[0] == 'd')
                res = (double)res/(1.0*log(10.0));
            ans += res;
        }
        printf("%.10f\n", -1.0*ans);
    }
    return 0;
}