循环-10. 求序列前N项和

#include <stdio.h>int main(void){    double t,sum=0,a=1,b=2,i=1,c;    int n;    scanf("%d",&n);    while(i<=n)    {        t=b/a;        c=b;        b+=a;        a=c;        i++;        sum+=t;    }    printf("%.2f",sum);    return 0;}