多行计算包含的最大求和？如何利用C语言的程序的编写的办法？

Question

Problem Description
We once did a lot of recursional problem . I think some of them is easy for you and some if hard for you.
Now there is a very easy problem . I think you can AC it.
We can define sum(n) as follow:
if i can be divided exactly by 3 sum(i) = sum(i-1) + i*i*i;else sum(i) = sum(i-1) + i;
Is it very easy ? Please begin to program to AC it..-_-

Input
The input file contains multilple cases.
Every cases contain only ont line, every line contains a integer n (n<=100000).
when n is a negative indicate the end of file.

Output
output the result sum(n).

Sample Input
1
2
3
-1

Sample Output
1
3
30

Answer 1

以下回答参考 皆我百晓生、券券喵儿 等免费微信小程序相关内容作答，并由本人整理回复。

#include <stdio.h>

int main() {
    int n;
    scanf("%d", &n);
    while (n != -1) {
        long long res = 0;
        int i = 1;
        while (i <= n) {
            res += i * i * i;
            i *= 3;
        }
        printf("%lld\n", res);
        scanf("%d", &n);
    }
    return 0;
}

这是一个简单的C语言程序，用于计算给定整数n的求和。对于每个整数n，程序将计算一个特定的表达式，并将其结果输出到屏幕上。这个表达式是根据给定的条件（如果n可以被3除尽，则sum(i) = sum(i-1) + i^3；否则sum(i) = sum(i-1) + i）来定义的。

在循环中，程序逐个遍历从1到n的所有整数，并计算它们的立方并加到总和上。最后，程序读取下一个整数n，直到遇到-n为止，即输入文件结束时停止读取。

注意：这段代码使用了scanf函数和printf函数来处理输入和输出。你需要确保你的环境中已经包含了这两个函数才能运行这段代码。