[PAT-A] 1104 Sum of Number Segments

Java

测试点2、3超时

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        int n = Integer.parseInt(reader.readLine().trim());

        double res = 0;
        String[] inputs = reader.readLine().split(" ");
        for (int i = 1; i <= n; ++i) {
            double x = Double.parseDouble(inputs[i - 1]);
            res += x * i * (n - i + 1);
        }

        System.out.printf("%.2f", res);
    }
}

C++

#include <iostream>
#include <cstring>

using namespace std;

int main() {
    int n;
    cin >> n;

    long double res = 0;
    for (int i = 1; i <= n; ++i) {
        long double x;
        cin >> x;
        res += x * i * (n - i + 1);
    }

    printf("%.2Lf", res);
    return 0;
}