View Code of Problem 71

#include<stdio.h>
#include<math.h>
int main()
{
	int n,i,j;
	double sum=0;
	int a1=1,a2=2,b;
	scanf("%d",&n);
	for(i=0;i<n;i++)
	{
		sum+=1.0*a2/a1;
		b=a1;
		a1=a2;
		a2=b+a1;
	}
	printf("%.2lf",sum);
}