直接计算分数的值即可
#include<stdio.h>
int main()
{
int n;
int p = 1,q = 2,pre_p,pre_q;
double sum = 0,mid;
scanf("%d",&n);
for(int i = 1;i <= n;i++){
mid = q / (1.0 * p);
sum += mid;
printf("p = %d,q = %d\n",p,q);
pre_q = q;
q = p + pre_q;
p = pre_q;
}
printf("%.4lf",sum);
return 0;
}