题解：P13897 [CSPro 28] 现值计算

#include <iostream>
#include <cmath>
#include <iomanip>
using namespace std;

int main() {
    int n;
    double i;
    cin >> n >> i;
    double total = 0.0;
    for (int k = 0; k <= n; k++) {
        int x;
        cin >> x;
        double discount = pow(1 + i, -k);
        total += x * discount;
    }
    cout << fixed << setprecision(3) << total << endl;
    return 0;
}