2011

求多项式的和

#include <stdio.h>

int main()
{
    int m, n, i, f = -1;
    double j,sum = 0;
    while (scanf_s("%d", &m))
    {
        for (i = 1;i <= m;i++)
        {
            scanf_s("%d",&n);
            f *= -1;
            j = 1.0 * f / i;
            sum += j;
            printf("%.2lf
",sum);
        }
    }
    return 0;
}

参考答案

#include<stdio.h>

int n;

double rev(int c)
{
    return c <= n ?( ((c & 1) ? 1.0 : -1.0) / c + rev(c + 1) ): 0 ;
}

int main()
{
    int t;

    scanf("%d", &t);
    while (t-- && scanf("%d", &n))
        printf("%.2lf
", rev(1));

    return 0;
}