有没有家人看看第十题😭😭急

https://img-mid.csdnimg.cn/release/static/image/mid/ask/236603388666184.jpeg

#include<stdio.h>
#include<math.h>
double s(int n){
    double sum = 0;
    for(int i = 0;i < n;i++){
        sum += (n + 1.0 * i);
    }
    return sum;
}
int main(void){
    int n,sign = 1;
    double y = 0;
    scanf("%d",&n);
    for(int i = 1;i <= n;i++){
        double fenmu = s(i);
        double fenzi = pow(i,2) * sign;
        y += (fenzi / fenmu);
        sign *= -1;
    }
    printf("%lf",y);
    return 0;
}