PTA——数列求和

程序：

 #include<stdio.h>

 int main() {

     int i,n;

     double fz = ,fm = ,sum = ;

     scanf("%d",&n);

     double s = ;

     for(i = ; i <= n; i++) {

         fm = fz;

         fz = sum;

         sum = fz + fm;

         s += fz/fm;

     }

     printf("%0.2lf",s);

 }