hd2011题 就是不知道哪里错了

#include<stdio.h>
int main()
{
    int m,a[1002];
    double b[1002],ans=0.0;

    while(scanf("%d",&m)!=EOF){
    int i;
    for(i=1;i<=m;i++)
    {
        scanf("%d",&a[i]);
        b[i]=1.0/a[i];

        if(i%2==0)
            b[i]=-1.0*b[i];
        ans+=b[i];  printf("%.2lf\n",ans);
    }
}
    return 0;
}

怎么提交都是错的

https://blog.csdn.net/i1020/article/details/51622305