交错级数求和

#include<stdio.h>

int main()
{
    int n;
    double sum=0.0;
    scanf("%d",&n);
    for(int i=1;i<=n;i++)
    {
        sum+=1.0/i;
    }
    printf("%f\n",sum);
    return 0;
}

#include<stdio.h>

int main()
{
    int n;
    double sum=0.0;
    int fact=1;
    scanf("%d",&n);
    for(int i=1;i<=n;i++)
    {
        sum+=1.0/i*fact;
        fact=-fact;
    }
    printf("%f\n",sum);
    return 0;
}